Wheel-Defects IR

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Wheel defects
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Code of Practice
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Wheel defects
Code of Practice
This Rail Industry Safety and Standards Board (RISSB) product has been developed using input from rail experts from across
the Rail Industry. RISSB wishes to acknowledge the positive contribution of all subject matter experts and DG
representatives who participated in the development of this product.
The RISSB Development Group for this Code of Practice consisted of representatives from the following organisations:
John Holland Metro Trains PTA

ATRC Queensland Rail Aurizon
DPTI TfNSW Pacific National
Development of this Code of Practice was undertaken in accordance with RISSB’s accredited processes. It was approved by
the Development Group, endorsed by the Standing Committee, and approved for publication by the RISSB Board.
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I commend this Code of Practice to the Australasian rail industry as part of the suite of RISSB products assisting the rail
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industry to manage rail safety, improve efficiency and achieve safety outcomes through interoperability and
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harmonisation.
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Deborah Spring
Chief Executive Officer | Executive Chair
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Rail Industry Safety and Standards Board

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Notice to users
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The reliance upon or manner of use of this RISSB product is the sole responsibility of the user who is to assess whether it
meets their organisation’s operational environment and risk profile.
Keeping Codes of Practice up-to-date

To maintain their currency, Codes of Practice developed by RISSB are periodically reviewed, and new editions published
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It is important that readers assure themselves of that they are using a current RISSB Code of Practice. Information about
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Wheel defects Page 2 of 61

Wheel defects
Code of Practice
Document Control
Identification
Document Title Version Date
Wheel defects 2.0 29 July 2020
Document History
Publication Version Effective date Page(s) Affected Reason for and extent of
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changes
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2.0 All New edition (CoP reviewed and
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updated)
Clarifications and correction of
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minor errors
1.1 15 Jul 2013 Errata – missing Appendix A Wheel

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measuring points inserted, and old
Appendix A & B become B & C
1.0 3 December 2012 All First Publication

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Approval
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Name Date
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Copyright
© RISSB
All rights are reserved. No part of this work is to be reproduced or copied in any form or by any means, electronic or
mechanical, including photocopying, without the written permission of RISSB, unless otherwise permitted under the
Copyright Act 1968.
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Wheel defects
Code of Practice
Contents
1 Introduction .................................................................................................................................. 6
Purpose .......................................................................................................................... 6
Scope .............................................................................................................................. 6
Normative references .................................................................................................... 7
Definitions ...................................................................................................................... 7
2 General requirements .................................................................................................................. 9
General ........................................................................................................................... 9
Wheel defect categories .............................................................................................. 10
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Wheel features ............................................................................................................. 11
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3 Wheel inspection ........................................................................................................................ 12
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Limiting dimensions .................................................................................................................... 14
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General ......................................................................................................................... 14
Wheel rim thickness ..................................................................................................... 14
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Permissible variation in wheel diameter ..................................................................... 14
Limiting tread and flange dimensions .......................................................................... 15
Movement of a wheel on axle ..................................................................................... 15
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Tyred wheels ................................................................................................................ 15

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5 Thermal cracks ............................................................................................................................ 15

6 Spalling and shelling ................................................................................................................... 18
7 Wheel flats .................................................................................................................................. 20
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8 Scaled wheels ............................................................................................................................. 22

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9 Arrises and other flange defects................................................................................................. 24

General ......................................................................................................................... 24
Arrises .......................................................................................................................... 24
Unacceptable flange conditions ................................................................................... 24
Tread and flange – wear and flow .............................................................................................. 27
General ......................................................................................................................... 27
Tread and flange wear conditions................................................................................ 27
Damaged / fractured wheels ...................................................................................................... 32
General ......................................................................................................................... 32
Cracked or broken web / plate .................................................................................... 32
Shattered rim defects .................................................................................................. 32
Cracked or broken wheel rim ....................................................................................... 33
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Cracked or broken flange ............................................................................................. 33

External wheel damage ................................................................................................ 33
12 Overheated wheels ..................................................................................................................... 36
13 Tread checks ............................................................................................................................... 38
14 Misaligned brake gear ................................................................................................................ 39

Wheel defects
Code of Practice
General ......................................................................................................................... 39
Temporary brake block overhang ................................................................................ 39
Permanent brake block overhang ................................................................................ 40
15 Out-of-round wheels .................................................................................................................. 40
Appendix A Wheel profile measuring points definitions (normative) ............................................ 42
Appendix B Wheel profile gauges (normative) ............................................................................... 45
Appendix C Inspection technologies ............................................................................................... 51
C.1 Common wheel inspection technologies ..................................................................... 51
C.2 Wheel impact load detectors ....................................................................................... 51
Appendix D Application of wheel gauges ........................................................................................ 53
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D.1 Types of gauges ............................................................................................................ 53
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D.2 High flange ................................................................................................................... 53
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D.3 Thin flange .................................................................................................................... 54
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D.4 Steep flange ................................................................................................................. 55
D.5 Rim thickness ............................................................................................................... 55
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D.6 Wheel condition warning gauges................................................................................. 56
D.7 Wheel tread hollowing ................................................................................................. 56
Appendix E Repair guidance............................................................................................................ 57
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E.1 General ......................................................................................................................... 57

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E.2 Thermal cracks ............................................................................................................. 57

E.3 Spalling and shelling ..................................................................................................... 57
E.4 Wheel flats ................................................................................................................... 57
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E.5 Scaled wheels ............................................................................................................... 58

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E.7 Tread and flange wear ................................................................................................. 58

E.8 Damaged / fractured wheels – external wheel damage .............................................. 58
E.9 Overheated wheels ...................................................................................................... 58
E.10 Tread checks................................................................................................................. 59
E.12 Out of round wheels .................................................................................................... 59
Appendix F Bibliography ................................................................................................................. 60
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Wheel defects
Code of Practice
1 Introduction
Purpose
This document describes requirements for the inspection and repair of freight, passenger, and
infrastructure maintenance rolling stock wheels, providing definitions and illustrations of wheel faults
and defects. Each defect category has a severity and corresponding action.
The main purposes of the requirements are to:
• reduce the risk of derailment arising from wheel failure;
• reduce the risk of damage to infrastructure caused by wheel defects;
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• minimise hunting/maintaining good vehicle stability; and
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• minimise wheel/rail contact stresses in order to prevent rolling contact fatigue in wheels
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and rails.
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Scope
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This Code is supplementary to AS 7514 and applies to new and existing locomotive, freight, passenger
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and infrastructure maintenance rolling stock.
This Code is not specifically intended to cover rolling stock used on light rail, cane railway and monorail
networks, but items from this Code may be applied to such systems as deemed appropriate by the
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relevant Railway Infrastructure Manager (RIM).

Dimensions and limit values given in this Code are primarily for wheels over 700 mm diameter. Where
smaller wheels are used, suitable adjustments to the wear and defect limits may be made by the RTO.
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The defect levels given in this Code are for operation at speeds below 200 km/h. For operational speeds
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above 200 km/h the defect levels given in this Code may be reassessed by the RTO / RIM based upon
the risk.
This Code prescribes a system of classification for several common defects and includes representative
photographs and/or figures. There are also instructions relating to the appropriate action to be taken in
the case of each defect. Where this Code prescribes a restricted speed for a defective vehicle the
maximum permitted speed over any track section is the lower of the speed prescribed by this Code and
the maximum permissible track speed for that section.
For operations with axle loads exceeding 30 t the specific wheel defect limits and their requirements for
qualifying wheelsets for service, including their methods of measure, are not included in this Code.
Likewise, the specific methods of repair, actions to be taken and permitted speeds may not be
applicable or acceptable to axle loads exceeding 30 t.
When moving rolling stock between differing networks e.g. DIRN and Pilbara networks, or between
Queensland, South Australia, Tasmania and Western Australia narrow gauge networks, the differing
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wheelset back-to-back dimensions, wheel cross-sections and profiles applicable to each network shall be
taken into account.
Application of this standard to infrastructure maintenance rolling stock that operate at speeds below 15
km/h or at rail wheel axle loads below 5 t needs to be assessed on an individual basis and RTOs should
develop specific wheel defect criteria where necessary.

Wheel defects
Code of Practice
Significant technical changes from the previous revision of this Code include:
(a) section and clause numbering from section 4 onwards to support relocation of the
following content to appendices:
i. inspection technologies;
ii. types of gauges; and
iii. repair guidance.
(b) section based numbering applied to tables (previously referred to as charts) and figures
throughout;
(c) removal of a measurement method for gauging rim thickness previously known as
alternative 2 and the associated figures;
(d) updates to figure 3:1 – Location of limiting dimensions (previously referred to as figure 2)
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and associated notes to:
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i. indicate a range of values for the flange angle secondary measurement point;
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ii. note known variations for flange thickness limits in use by RTOs.
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Normative references
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The following reference documents are indispensable for the application of this Code of Practice:
(a) AS 7514 – Wheels.
(b) AS 7517 – Wheelsets.
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Definitions
For the purposes of this Code of Practice the definitions given in the RISSB glossary of terms shall apply.
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The following definitions are specific to this Code:

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(a) arris
raised lip near the flange tip caused by metal flow under load
(b) back
face of a wheel on the flange side
(c) class
grade of wheel defect severity
(d) competent person
person who carries out assessment and has suitable or sufficient skill, knowledge,
experience and qualifications as determined by their organization
(e) cutter block
special brake block (or cutting shoe) that is utilised for the purpose of reconditioning a
wheel tread
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(f) flange
protruding portion of a wheel profile, the function of which is to provide lateral restraint
and guidance by making contact with the gauge face of the rail head
(g) front
face of a wheel on the non-flange side

Wheel defects
Code of Practice
(h) heat check

wheel tread surface checking (a network of fine cracks) caused by heat input from tread
braking that is not cause for wheel removal
(i) hub
central portion of a wheel that interfaces with the axle. Also known as the boss
(j) infrastructure maintenance rolling stock
track machines and road-rail vehicles used for infrastructure maintenance, construction, or
inspection
(k) maintenance officer
person with experience identifying wheel defects
(l) out-of-round wheel
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wheel that exhibits rim radial run out that exceeds the maximum permissible. Includes
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wheel tread corrugation
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overheated wheel
wheel that has been subjected to potentially damaging thermal input, typically as a result
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of heavy braking or sticking brakes
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(n) remove from service
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removal of vehicle from service within the specified time until the damaged wheelset is
replaced by a serviceable wheelset or where appropriate, machined on an underfloor lathe
(o) rim
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outer portion of a wheel that interfaces with the rail

(p) rim face
vertical front (outer) or back (inner) surface of the rim
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(q) rim width

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distance between the faces of the rim

(r) rolled edge
lip overhanging the rim face formed by metal under load flowing from the tread,
typically occurring fully around the circumference of the wheel
(s) rolling-contact fatigue
mechanism of crack generation and propagation caused by the near surface alternating
stress field that exists within rolling-contact bodies, which eventually leads to loss of
material
(t) scaled wheel
wheel that has a build-up of metallic scale on the surface of the tread. Also known as metal
build up
(u) shelling
circumferential metal loss (breakout) from a wheel tread due to rolling-contact fatigue. Also
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known as shelled tread

(v) skidded wheel
wheel that has experienced a skid/slide after a "lock-up" under braking

Wheel defects
Code of Practice
(w) shattered rim

defect initiated at a sub-surface defect within the wheel rim, resulting in loss of a segment
of the wheel tread. Also known as deep shelling
(x) spalling
localised loss (breakout) of metal from a wheel tread due to (brittle) martensite formation
at the tread surface as a result of wheel skid/slide
(y) spread rim
localised form of rolled edge generally caused by out-of-round wheel impacts or local
fatigue cracking (a sub-set of the shattered rim defect)
(z) thermal crack
transverse crack in the tread resulting from alternate heating and cooling of the wheel
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tread and rim
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(aa) tread
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portion of a wheel profile that makes contact with the upper surface of the rail head
(bb) tread checking
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series of fine linear ridges in a wheel tread, often inclined, that could result from high
wheel-to-rail contact stresses. Also known as stress checking
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(cc) tread line
datum line drawn on a wheel profile to indicate the position at which wheel diameter
should be measured. Also known as the taping line. The position of the tread line may be
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approximately that of the circle of contact of a new wheel and unworn rail (mean position),
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subject to wheel profile and rail head contour and the position will vary, depending on
which standard has been adopted for the wheel profile
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(dd) web
section between the wheel hub and the wheel rim. Also known as the plate
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(ee) wheel flat

flattened zone on the tread of a skidded wheel
(ff) wheelset
assembly consisting of axle, wheels and bearings, and where applicable brake discs, traction
gears, traction motor support bearings or gearbox
(gg) work out of service
arrange for a defective vehicle to be removed from service for repair upon reaching its
current allocated destination or on-route if reasonable to do so
2 General requirements
General
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Wheel defects are classified according to their severity. A Class 1 defect is the least severe and a Class 5
defect is the most severe. Table 2:1 summarises the definitions that should be implemented in respect
of each defect classification.

Wheel defects
Code of Practice
Table 2:1 - Wheel defect classification and definitions

Wheel defect classification Definition
Class 1 Visual damage which does not impact rolling stock operation.
Class 2 Minor damage which requires reporting ongoing monitoring.
Class 3 Damage which requires ongoing management to assess the operational risk to
rolling stock.
Class 4 Damage which requires ongoing management to assess impact to the
operation risk to infrastructure.
Class 5 Severe damage. Vehicle not to run until defect rectified or wheel removed.
NOTE 1. An RTO should categorise and record the reasons for the removal of wheels from service.
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NOTE 2. Moving a vehicle with Class 3 or greater defects presents operational risks to the RTO and or RIM. This Code does not
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specify operational outcomes for these defects, as this risk is managed at an organizational level.
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Wheel defect categories
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The following are the principal types of defect and unacceptable wheel condition:
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(a) Rolling contact/thermal fatigue defects Initiated from surface or near surface:
i. Thermal cracks - see Section 5.
ii. Shelling - see Section 6.
iii. Tread checks - see Section 13.
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(b) Defects caused by heat generation from sliding:

i. Spalling - see Section 6.
ii. Wheel Flats - see Section 7.
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iii. Scaled wheels - see Section 8.

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(c) Defects caused by wear, flow, and improperly steering bogies:

i. Arrises & flange defects - see Section 9.
ii. Steep flanges - see Section 10.2.1.
iii. High flanges - see Section 10.2.2.
iv. Hollow tread - see Section 10.2.3
v. Rolled edges / spread rim - see Section 10.2.4.
vi. Flange Plastic Flow - see Section 10.2.5.
(d) Fatigue defects originated below the surface:
i. Cracked or broken web / plate - see Section 11.2.
ii. Shattered rim - see Section 11.3.
iii. Cracked or broken wheel rim - see Section 11.4.
iv. Cracked or broken flange - see Section 11.5.
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(e) Defects that cause or result from impacts:

i. Dented flange - see Section 11.6.
ii. Wheel distortion - see Section 11.6.
iii. Out of round wheels - see Section 15.

Wheel defects
Code of Practice
(f) Defects associated with braking:

i. Overheated wheels - see Section 12.
ii. Misaligned brake gear - see Section 14.
Wheel features
Figures 2:1, 2:2 & 2:3 identify common important wheel features. Refer to Figure 3:1 and Appendix A for
diagrams indicating common defining points as to where to measure critical parameters.
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Figure 2:1 - Wheel disc terminology Figure 2:2 - Location of wheel limiting dimensions
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Figure 2:3 – Wheel shape definition

Wheel defects
Code of Practice
3 Wheel inspection
Wheels shall be inspected for profile, flange, tread, rim and general physical condition. A wheel can be
condemned because of:
(a) thin flange;
(b) steep flange;
(c) high flange;
(d) thin rim;
(e) hollow tread;
(f) flange defects;
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(g) tread defects;
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(h) irregularities in contour including grooving;
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wheel out-of-roundness; or
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(j) fractures and overheating.
This document generally describes the visual and manual methods of wheel inspection. However,
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Appendix C provides guidance for more modern inspection technologies available that can also be used.
Wheels should be inspected, and action taken in accordance with Tables 5:1 to 13:1 of this Code. Rolling
stock shall be repaired or removed from service if wheels or wheelsets exceed the limits imposed by the
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relevant wheel gauges which represent the limiting parameters as shown in Tables 4:1 and 4:2.
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See Figure 3:1 for locations of limiting dimensions. The figure shows new profiles, but the definitions
also apply to worn profiles.
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Wheel defects
Code of Practice
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Figure 3:1 – Location of limiting dimensions

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d: Wheel diameter l: Rim width e: Flange thickness¹

h: Flange height δ: Flange angle² t: Rim thickness³
x: Flange angle secondary measurement point²
Note 1. Currently there is no consistent standard for measurement of flange thickness in Australia as the flange
thickness is associated with the particular gauges being used by the RTOs. For the purpose of this Code, flange
thickness limits will be related to the gauges presently in use and varies slightly between gauges used, at a height
between 10.5 mm ±0.5 mm above the tread line point, except for Queensland Rail who measure the flange
thickness between 16 mm ±0.5 mm above the tread line point.
Note 2. Flange angle is measured at any point between 13 - 18 mm above the tread line point.
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Wheel defects
Code of Practice
4 Limiting dimensions
General
The accuracy of gauges used for checking limiting dimensions shall regularly be verified against
approved standards.
Wheel rim thickness

Table 4:1 - Summary of limiting rim thickness
Limiting dimension
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Tread-braked wheels – Low stress design (S-shaped web)
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20 mm
Up to 25 tonnes axle load
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Over 25 tonnes axle load
22 mm
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Tread-braked wheels - Traditional
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20 mm
Operations up to 80 km/h
25 mm
Operations over 80 km/h
25 mm
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Locomotives
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Disc-braked wheels
22 mm
Locomotives
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20 mm
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Passenger vehicles
Note 1. Traditional wheels refers to wheels that have no low stress design, e.g. wheels with UIC web or straight web.
Note 2. The values in 4:1 shall be applied regardless of rim thickness definition. Allowable rim thickness definitions are defined
in Figure 3:1.
Note 3. Special consideration may be required for wheels of less than 700 mm diameter.
Note 4. If the wheels have a condemning groove, the rim thickness can be checked visually. The requirement for continued
service then is that the condemning groove is fully visible and unaffected by wear.
Note 5. Wheels with rim thickness less than the limiting dimensions in Table 4:1 shall be worked out of service within 14 days.
Permissible variation in wheel diameter

Maximum variation in wheel tread diameter on a wheelset shall be as specified in AS 7517.
Note: Normally wheel diameters are only checked at wheelset exchange or at wheel reprofiling.
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Wheel defects
Code of Practice
Limiting tread and flange dimensions

Maximum permissible tread and flange parameters shall be as per Table 4:2.
Table 4:2 - Summary of limiting wheel parameters (in train inspections)

Limiting dimensions
Maximum permissible flange height
All vehicles 35 mm
Maximum permissible tread hollowing
All vehicles 3 mm
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Minimum permissible flange thickness
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Using gauges 307 0030, 17-4-1, 207-661 (see note 1) or equivalent 19 mm
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Queensland Rail Narrow gauge network 22 mm
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NOTE 1. Gauge 207-661 is to be used for indication only. Gauges 307-030 and 17-4-1 are the definitive condemning gauges.
Movement of a wheel on axle

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Any wheel that exhibits movement relative to its axle shall be immediately removed from service.
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Symptoms of wheel movement are wheel seat becoming visible or back-to-back measurement getting
out of tolerance.
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Tyred wheels
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Tyred rail wheels shall be inspected either before each trip or at intervals less than 1000 km.
Tyred wheels shall be removed from service if identified with any of the following criteria:
(a) Loose tyre rotation around the wheel centre.
(b) Detachment of retaining ring.
(c) Cracked spokes.
(d) Cracks or flaws on any wheel disc or centre.
5 Thermal cracks
Thermal cracks are the result of alternate heating and cooling of the wheel tread and rim area, and are a
severe form of wheel defect, see Figures 5:1 to 5:4. These cracks originate from areas of metallurgical
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change which occur in the wheel material during thermal cycling.

Heating from braking produces a network of fine, shallow, superficial lines or "heat checks" running in
many different directions on the wheel tread surface. Because of its similarity to the type of fine cracks
found in pottery glazes, it is sometimes referred to as surface crazing. This should not be confused with
true thermal cracking, and if found on its own causes no problems.

Wheel defects
Code of Practice
Thermal cracks are generally transverse (across the tread) and if allowed to grow without corrective
action can quickly lead to brittle failure and the wheel will fracture.
If there is any doubt as to the severity of the thermal crack, the higher classification shall be reported.
Refer to Table 5:1 for description of the defect and actions to be taken.
If a vehicle is detected with thermal cracks, the brake system shall be checked for correct operation and
correct type of brake blocks. Where cracks are found outside the shaded area according to Table 5:1,
brake alignment with the tread (i.e. no brake show over hanging the rim edge) shall be checked.
Lateral and longitudinal surface traction forces can also produce a series of fine checks on the wheel
tread caused by rolling contact fatigue (not to be confused with thermal cracks). These are generally
inclined at a 45-degree angle and most commonly occur near the front face of the wheel and flange
where the wear rate is low (see Section 13).
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Figure 5:1 – Class 2 Thermal crack Figure 5:2 – Class 3 Thermal crack
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Figure 5:3 – Class 4 thermal crack Figure 5:4 – Class 5 Thermal crack

Wheel defects
Code of Practice
Table 5:1 - Thermal cracks
Class Description of defect Action required Speed restriction

Cracks up to 10mm long in shaded area,
but not extending outside of shaded area
1 No action required Normal speed
Cracks between 10mm and 30mm long in Wagons & infrastructure

shaded area, but not extending outside of maintenance Re-examine
shaded area carefully to ensure that no
Class 3 Thermal cracks
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exist. Defects shall be
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reported.
2 Normal speed
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Defects shall be reported
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and scheduled for re-
examination at the next
general inspection or at no
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greater than 10,000 km.
Cracks between 30mm and 40mm long in If wheel is approaching

shaded area or less than 10mm long in rim condemning diameter,
area or rim face treat as Class 4 defect.
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Wagons & infrastructure

maintenance: Work out of
3 Normal speed
service.
Passenger & locomotives:
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Defects shall be reported

and scheduled for turning
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within 14 days.
Any visible cracks in the flange surface If found pre-trip or at a

outside the shaded area, or cracks depot, the wheel shall not
greater than 10mm long the rim enter service. If found en-
surfaces outside shaded area or route continue at reduced
extending from it, or cracks greater than speed with the brakes cut Speed
4 40mm long anywhere on the wheel out. 40 km/h maximum
Locomotives: The use of
the independent brakes
should be kept to a
minimum.
Examine defect in the

section before movement
Fractured wheel to the nearest siding at the NOT TO RUN
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Any crack running though the rim, web or hub of wheel speed nominated by the Until wheel inspected
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attending maintenance
officer.

Wheel defects
Code of Practice
6 Spalling and shelling

Spalling occurs when pieces of metal break out of the tread surface in one or several places, see Figures
6:1 to 6:4. This defect can be caused by thermal damage, skidding or over-stressing at the wheel-rail
contact point. It is usually attributed to a combination of two or more of the following factors: poor
track and excessive speed resulting in high impact loads, excessive vertical loads, excessive braking
(thermal damage and/or skidding) or the use of wheels of insufficient hardness or metallurgical quality.
Spalling and shelling can have a similar appearance, but their generation mechanisms are different. The
appearance of spalls or shelling could alter depending on the causes. Normally shelling is spread out
around the circumference of the wheel, while spalls are more local.
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Spalls result from the fracture under loading of a hard and brittle martensite steel phase which forms
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when the wheel tread locally undergoes rapid heating and cooling due to wheel skidding from braking,
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or lateral slip at special track work and check rails.
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Shelling results from a subsurface rolling contact fatigue defect which forms due to pure rolling contact
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fatigue, or under the multiple actions of tangential stresses predominantly at stringers of oxide
inclusions in the wheel steel, or under normal, lateral and traction loads and residual stresses.
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Spalling defects can range in size depending on the age and depth of the defect. Their frequency can be
such that the entire tread circumference is covered with craters to the extent that they become joined.
Wheel tread condition, particularly spalling, has a pronounced effect on wheel and brake block life.
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Pitting is the presence of very small marks on the tread. It can be the initial stages of spalling but is not
in itself a concern.
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The higher class of spalling shall be reported if there is any doubt about the severity of the defects.
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Refer to Section 4.6 for inspection of defects related to wheel tread impact load detectors and overall
length of defect.
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Wheel defects
Code of Practice
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Figure 6:1 – Class 1 Spalling Figure 6:2 – Class 2 Spalling
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Figure 6:3 – Class 3 Spalling Figure 6:4 – Class 4 Spalling

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Wheel defects
Code of Practice
Table 6:1 - Spalling

Speed
Class Description of defect Action required
restriction
Spalled regions with cavities less than 12 mm in diameter. No action required Normal
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Maximum 10%-wheel coverage speed
Spalled regions with cavities less than 25 mm in diameter. Re-examine carefully to ensure that no
Normal
2 Maximum 20%-wheel coverage. The edges of the spalls Class 3 spalls exist. Defects shall be
speed
could be sharp and jagged. reported.
Locomotives & passenger: Remove from

Spalled regions with cavities greater than 25 mm in service within 14 days. Normal
3 diameter, no deeper than 3 mm. The edges of the spalls
Wagons & infrastructure maintenance: speed
could be sharp and jagged. Maximum 50%-wheel coverage.
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Work out of service.
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If found pre-trip or at a depot, the wheel
4 ub Pr fec
Extensive spalling 3 mm or more deep, sharp and jagged.
More than 50%-wheel coverage.
shall not enter service. If found en-route
continue at reduced speed with the brakes
Speed
40 km/h
m
maximum
cut out or work out of service.
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7 Wheel flats
Wheel flats occur when the wheels lock-up under braking and slide or skid along the rail while the train
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is in motion, see Figures 7:1 to 7:3. The heat generated when skidding will affect the underlying
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material. If the temperature is high enough and is followed by rapid cooling, the material will transform
into a hard, brittle phase called martensite which also expands in volume. Due to the brittleness and the
internal stresses caused by the difference in volume, cracks will start to generate in and/or around the
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martensite patch when the wheel starts rolling again. This will eventually lead to further wheel damage
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such as spalling. The resultant impact forces are detrimental to the track structure and reduce the life of
other bogie components, particularly bearings.
If there is any doubt about the severity of a wheel flat, the higher class of defect shall be reported.
When measuring skidded wheel defects, the effective length of the defect should be assessed. Often
using a straight edge and rocking it on the flat and the immediate area near the visible flat spot area, will
reveal the total length of the affected tread. It is this overall length that shall be used for corresponding
actions.
length of defect.
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Wheel defects
Code of Practice
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Figure 7:1 – Class 3 skidded wheel Figure 7:2 – Class 4 skidded wheel
(multiple class 2 skids)
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Figure 7:3 – Class 5 Skidded wheel

Wheel defects
Code of Practice
Table 7:1 – Flat wheels

Recommended
Class Description of defect Action required speed
restriction
1 Single skid length less than No action required.
Normal speed
25 mm.
2 Single skid length between Defects shall be recorded by the RTO and may be required to be
25 mm and 40 mmᵅ or reported to the RIM. Normal speed.
multiple Class 1 skids. Trim blocks may be used.
3 Single skid length between Work out of service.

40 mmᵅ and 60 mm or Defects shall be recorded by the RTO and may be required to be 60 kph
multiple Class 2 skids. reported to the RIM.
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4 Skid length between 60 mm If found pre-trip or at a deport, the wheel shall not enter service.
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and 100 mm or multiple If found en-route continue at reduced speed with the brakes cut 60 kph
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Class 3 skids.
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Skid length greater than
out and work out of service.
If found pre-trip or at a depot, the wheel shall not enter service.
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100 mm or multiple Class 4 Movement
If found en-route, remove built-up metal prior to movement to the
skids. from siding to be
nearest siding at a speed nominated by the attending maintenance
assessed in
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officer and RIM.
conjunction with
Wheel shall be made safe for movement from siding prior to the the RIM.
rolling stock being moved.
ᵅ Queensland Rail use 50mm.

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NOTE 1. Trim blocks can be a fire hazard and cause thermal stresses to the wheel.
NOTE 2. The best measure to minimize damage to track and wheelset bearings is to remove skidded wheels from service as
soon as possible.
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8 Scaled wheels
Scaling is the build-up of metallic material on the surface of the wheel tread, see Figures 8:1 to 8:2. It is
usually attributed to sticking brakes which cause the wheel to skid or slide on the rail, thus heating the
contact patch to the stage where the wheel material becomes soft enough to flow on the tread surface.
The flowing material mixes with brake dust and other foreign material and is deposited back onto the
wheel where it cools in layers, giving the tread a scaly appearance.
Scale can cover the entire wheel surface or any part thereof. The severity of the scaling is assessed by
measuring the height of the scale above the normal wheel tread surface.
If there is any doubt about the severity of the scaling, the higher class shall be reported.
Note that severity Classes 1 and 2 are not applicable to scaled wheels; the minimum detectable amount
of scaling is classified as a Class 3 defect.
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length of defect.

Wheel defects
Code of Practice
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Figure 8:1 – Class 3 Scaled wheel Figure 8:2 – Class 4 Scaled wheel
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Table 8:1 - Scaled wheels

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Speed
restriction
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1&2 Classification not relevant Not relevant Not relevant

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Light surface smearing too small to Examine brake gear for defects Normal speed
3
measure with a standard rule
Speed 25 km/h
4(i) Scale height up to 5 mm
maximum
If found pre-trip or at a depot the wheel shall not

Speed 5 km/h
(ii) Scale height 5 mm to 10 mm enter service. If found en-route clear the section at
maximum
reduced speed with vehicle brakes cut out
Speed 5km/h
(iii) Scale height 10 mm to 15 mm
maximum
5 Scale height greater than 15 mm Rectify defect in the section before movement to the NOT TO RUN
nearest siding at a speed nominated by the attending until wheel is
maintenance officer rectified
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Wheel defects
Code of Practice
9 Arrises and other flange defects

General
Arrises and other flange defects include wear grooves, machining grooves or steps, flat tops and other
damage can occur in service.
Arrises
Arrises or raised lips on the top of the wheel flange are due to metal flow. If allowed to progress to a
sufficient extent they can result in points being split, particularly if occurring in conjunction with steep or
thin flanges.
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If a brake block contacts an arris, they will rapidly heat and cool resulting in thermal cracking. Arrises are
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classified according to the height above the normal top of the flange.
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If arrises are frequently occurring, the root cause should be investigated. The root cause could be lack of
proper rail gauge face lubrication and/or excessive force on the flange due to a rolling stock defect.
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Unacceptable flange conditions
Several flange conditions experienced in service are unacceptable and pose a significant risk of
derailment and/or damage to track components. Certain patterns of wear and damage to the flange
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surface, particularly on the flange top and back, can also result in incidents and therefore when found
should be marked for repair or replacement. Irregularities can arise from inappropriate manufacturing
or maintenance procedures as distinct from service conditions. Condemning gauges cannot always
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detect irregularities of this kind even though they could render a wheel condemnable.
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Typical conditions are illustrated in Figure 9:1 below and include the following:
(a) Wear grooves, gouges, or deformation on the top portion of the flange or back face.
(b) With the exception of witness marking; undercut, coarse marks or a step-like surface
caused by wheel machining.
(c) Abrupt changes in flange profile.
(d) Wide flat faces on the flange top.
(e) Sharp or square flange top.
(f) Irregularities in contour or profile.
All the above irregularities have the capacity under certain conditions to induce rail climb or to split
points. Wheelsets with these defects shall be removed from service. Examples of track conditions
aggravating the situation are damaged switch tips/point blade tips or a switch not properly seated
against the stock rail.
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Wheels with a sharp flange top can develop fatigue cracks within the flange.

Wheel defects
Code of Practice
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Figure 9:1 – Unacceptable flange conditions

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Wheel defects - Code of Practice
Table 9: 1 – Arises Table

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1 Classification not relevant Not relevant Not relevant
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Arris less than 1.5mm
Re-examine carefully to ensure that no
2 thermal cracks exist. Defects shall be Normal speed
reported.
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Over 1.5mm high above the tip
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of the flange and where the arris
3
i
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is rolled back towards the flange
Locomotives and passenger: remove from
service within 14 days.
Normal speed
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Wagons and infrastructure maintenance:
Work out of service.
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Arris less than 1.5mm

If found pre-trip or at a depot, the wheel
Near vertical flange face
shall not enter service. If found en-route
Full flange profile
continue at reduced speed with the brakes Speed 40 km/h over points, cross-
4
cut out after traffic approval from the overs and turnouts.
attending maintenance officer or remove
from service.

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Wheel defects
Code of Practice
Tread and flange – wear and flow

General
Wheel wear and condition is determined by application of a standard wheel condemning gauge (refer to
Appendix D). Flange condition is determined in relation to the thickness, slope and height above the
tread.
Flange and tread condition also require evaluation of plastic flow such as the presence of arrises
(flange lips) or rolled edges.
Vehicles should leave a repair facility with a sufficient flange thickness wear margin, which will allow
operation until the next wheel inspection is due to be carried out by the RTO. Refer to the RIM for other
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specific requirements for each Network.
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Tread and flange wear conditions
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10.2.1 Steep flanges
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To determine whether the flange is partly or wholly steep, the whole wheel shall be visually examined.
Flange steepness shall be assessed at the circumferential position of maximum apparent flange
steepness. If there is any doubt in the visual assessment, the flange steepness shall be checked with a
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condemning gauge – refer to Appendix D for guidance.

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All bogies with steep flanges shall be further examined for other defects.
Steep flanges can be an indication of other problems, for example:
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(a) One steep flange only could indicate a wheelset that has a variation in wheel diameters.
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(b) Two steep flanges on diagonally opposite corners could indicate a crabbing effect due to
side frame misalignment.
(c) Two steep flanges on same side could indicate mismatched side frame lengths.
(d) Four steep flanges could indicate a hunting condition caused by worn friction wedges or
side-bearers.
10.2.2 High flanges
The height of a flange above the tread shall not exceed 35 mm as shown in Table 10:1. The height may
be determined by the application of an appropriate wheel gauge. Wheels with this condition can lead to
the flange tip bottoming through track features such as K crossings and frogs, increasing wear and the
risk of derailment. High flanges can also damage fishplates and bolts on light rails, cause damage to
inductive type axle counters, and transducers used by hot box and wheel tread impact detectors.
10.2.3 Hollow tread

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Hollow tread limiting dimensions should be ascertained from the RIM for the networks on which the
rolling stock is to operate.
Hollow tread results in the loss of effective wheel conicity that produces high flanges and significantly
reduces the tracking ability of a bogie. To determine the presence of hollow tread it is necessary to carry

Wheel defects
Code of Practice
out a visual examination, which includes the use of a gauge. Appendix D provides additional information
on types of gauges commonly used.
The hollow tread limit is set to manage the following issues:
(a) Rolling contact fatigue and deformation of plain rail.
(b) Damage at switches and crossings.
(c) Worsened steering – resulting in increased susceptibility to hunting and increased fuel
consumption.
10.2.4 Rolled edges / Spread rim
Rolled edges are the result of metal being rolled across the tread toward the outside (for flangeless
wheels also the inside) of the wheel, where it forms a lip overhanging the rim face.
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The lip, thus formed, facilitates initiation of thermal and fatigue cracks which can progress into the rim
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face. This can result in a severely increased risk of a catastrophic wheel failure.
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Spread rim is the result of a local lateral rim surface flow caused by out-of-round wheel impacts and/or
rim weakening due to circumferentially oriented fatigue cracks. Figures 10:1 and 10:2 give example of
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local lateral rim surface flow and spread rim. High lateral contact stresses due to incorrectly tracking
vehicle often is a contributing factor. See also description in Section 11.3 “Shattered Rim Defects”.
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Any rolled edge or lip of this type which extends more than 3 mm past the vertical face of the rim as
shown in Figure 10:3 is classified as a Class 3 defect. Vehicles with this defect shall be marked and
worked out of service. No speed restriction is required.
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Any wheel identified with a spread rim / shattered rim shall immediately be removed from service.
Any cracks found on the rolled edge shall be treated as a Class 4 thermal crack.
10.2.5 Flange plastic flow

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Plastic flow towards the top of the flange can occur in curves and turn-outs as a result of poorly steering
bogies and high friction between wheel and rail. Worn rail heads and worn wheel profiles will aggravate
the situation, particularly if the worn profiles mismatch so that two-point contact is established between
wheel and rail. This can lead to a steep flange or generation of a sharp edge or burr on the active part of
the flange that could impose an increased risk of derailment. See also Section 9.2 Arrises.
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Figure 10:1 – Lateral rim surface flow Figure 10:2 – Spread rim

Wheel defects
Code of Practice
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Figure 10:3 – Rolled edge limit
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Figure 10:4 - Rolled edge

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Copy of Copy of Workplan FY2020-21 WIP post SDM consultation2
Table 10:1 – Tread and flange wear and flow

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Locomotive and passenger: Remove from service
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Flange angle less than
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5 degrees from vertical within 14 days.
Wagons and infrastructure maintenance: Work out
m
of service.
3 Normal
Examine bogie and check wheel diameters for
Steep flanges Speed
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possible cause of steep flanges.
Note: A steep flange in conjunction with a Class 2
arris is a Class 4 defect. Treat as per Class 4 arris
(Table 10:1)
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3
High flanges
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Full flange profile
Greater than
35mm
Locomotives and passenger: Remove from service
within 14 days.
Wagons and infrastructure maintenance: Work out
Normal
Speed
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of service.
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Tread line
Hollowing assessed as Horizontal line drawn from highest Locomotives and passenger: Remove from service
greater than 3mm point of wheel tread front within 14 days.
3 Wagons and infrastructure maintenance: Work out Normal
Hollow tread of service. Speed
Note that the 3 mm hollow wear limit applies at
any point across the tread.
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Copy of Copy of Workplan FY2020-21 WIP post SDM consultation2
Table 10:1 – Tread and flange wear and flow

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See
Table
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4:2 Locomotive and passenger: Remove from service
10.8mm
within 14 days.
3
Normal speed
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Thin flanges
Wagons and infrastructure maintenance: Work
out of service.
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Tread line
ft od ee Locomotive and passenger: remove from service

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3 within 14 days.
Normal speed
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Rolled flanges Wagons and infrastructure maintenance: Work
out of service.
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Wheel defects
Code of Practice
Damaged / fractured wheels

General
The severity Classes 1, 2 and 3 are not applicable to damaged or fractured wheels.
Cracked or broken web / plate

A material fault or mechanical damage on the wheel web / plate can induce a fatigue crack which
depending on the position on the web often propagates circumferentially around the web. Increased
stress levels due to wheel rim overheating increase the risk.
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Any wheelset detected with a cracked web / plate shall be removed from service immediately and the
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wheel not used again in service. The root cause of the incident should be investigated, and actions taken
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to prevent recurrence.
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Shattered rim defects
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Shattered rim, deep shelling and spread rim are defects counted as shattered rim defects, see Figure
11:3 to 11:4. Their appearance can vary depending on where in the rim the defect is initiated. Also, the
wheel rim residual stresses and the load conditions have an influence.
Shattered rim defects originate from a sub-surface fatigue crack normally initiated at a slag inclusion,
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void or another type of metallurgical inhomogeneity within the wheel rim. Increased stress levels as a
result of track irregularities, e.g. corrugation, or wheel out-of-roundness promote the initiation. After a
propagation stage normally including several hundred thousand kilometres of travelled distance a
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substantial part of the wheel tread could break away. Until the sub-surface crack becomes surface-
breaking, it can only be detected in service by use of ultrasonic non-destructive testing. Appendix C
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provides additional guidance on inspection technologies. Once the crack has propagated sufficiently to
reach the rim face, they can be found at visual inspection. Visual indicators include rolled edge or a
bulging on the front face.
The consequences of a loss of a wheel tread segment due to the full development of a sub-surface crack
can be severe, especially if the segment includes the wheel flange, and involves a substantial derailment
risk. Due to the safety implications higher speed applications often undergo controls to mitigate the
derailment risk associated with shattered rim defects.
Preventive measures include:
(a) improvement of steel quality with respect to cleanliness, non-metallic inclusions and
homogeneity;
(b) removal of high impact wheels from service;
(c) improvement of track maintenance, particularly rail corrugation grinding.
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Any wheel identified with a shattered rim defect shall immediately be removed from service and the
root cause investigated. For small shattered rim defects found in an early stage at ultrasonic inspection
the time for removal can be adapted to operating conditions.

Wheel defects
Code of Practice
Cracked or broken wheel rim

Cracked or broken wheel rims are characterised by brittle fracture transverse to the running direction
originated from stress concentration or internal defect in the wheel rim. This type of defect is referred
to as a fatigue crack, and usually appears as a solitary crack and shall not be confused with thermal
cracks, see Figure 11:1.
Any fatigue crack found in a wheel rim shall be classified as a Class 4 defect or a Class 5 defect (see Table
11:1).
Cracked or broken flange

Flange failures can be caused by insufficient track clearance or too high flanges. Metallurgical
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inhomogeneities or manufacturing errors can also be the cause of fatigue crack initiation leading to
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flange failure. These types of defects often lead to large pieces of the flange falling off in service.
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Any fatigue crack found in a wheel flange shall be classified as a Class 4 defect or a Class 5 defect
(see Table 11:1).
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External wheel damage
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External wheel damage generally occurs as the result of a heavy impact on the wheel and could show up
as a chip or gouge in the wheel flange or a bruise on the wheel tread, see Figure 11:2. A fatigue crack
can start at this defect and propagate quickly through the entire wheel. Heavy impacts from a
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derailment often lead to distortion of wheels and/or axles.

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A close visual examination shall be made of both flange surfaces and wheel treads in order to detect the
presence of any damage.
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Any chip or gouge in a wheel which is more than 25 mm long and/or 12 mm wide shall be classified as a
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Class 4 defect (see Table 11:1).

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Figure 11:1 – Cracked or broken web

Wheel defects
Code of Practice
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Figure 11:2 – Scrape, dent or gouge
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Figure 11:3 – Shattered rim

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Wheel defects
Code of Practice
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Figure 11:4 - Spread rim
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Table 11:1 – Damaged / Fractured Wheel Table

Speed
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restriction
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1,2 & 3 Classification not relevant Not relevant Not relevant
Fatigue cracks in wheel rim or flange

Solitary cracks that are not running through the
rim of the wheel (no critical propagation), usually If found pre-trip or at a depot, the wheel
initiated from a manufacturing defect. shall not enter service. If found en-route Speed 40 km/h
4
continue at reduced speed with the Maximum
External wheel damage generally results from brakes cut out or remove from service
heavy impact loads on the wheel which can show
up as a chip or gouge in the flange or as a bruise
on the tread or a wheel distortion.
Fractured wheel
Any crack running though the rim, web or hub of
Examine defect in the section before
the wheel Not to run until
movement to the nearest siding at a
5 wheel has been
speed nominated by the attending
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Shattered wheel inspected

maintenance officer.
Circumferential crack visible on rim face, often in
combination with break-away of rim material

Wheel defects
Code of Practice
12 Overheated wheels
Hot or overheated wheels are identified as follows:
(a) For wheels which have been painted on the plate surface with a heat-sensitive paint
blistering or discolouration of the paint below the rim of the grey temperature indicating
coating. By a heat-sensitive paint is meant a paint of light colour that turns brown at
temperatures above 250°C, e.g. grey alkyd paint.
(b) For wheels that have not been painted, blueing discolouration or rusting of the plate
surface below the rim. Depending on temperature a freshly oxidised surface will appear
pink, violet or blue in colour, and will become darker with age, see Figure 12:1.
Any wheel which has become severely overheated due to excessive braking or sticking brakes is a Class 4
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defect and should be removed from service. Refer to Table 12:1 for description of the defect and actions
to be taken for unpainted wheels and Table 12:2 for painted wheels.
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Figure 12:1 - Overheated wheel

Wheel defects
Code of Practice
Table 12:1 – Overheated unpainted wheels

3 Rim oxidation (Rim overheated) Work out of service Normal speed

Oxidation evident on wheel rim and web but less
than 80 mm from the intersection between the
back or front face and the underside of the rim.
4 Web oxidation (Web overheated) If found pre-trip or at a depot the Speed

wheel shall not enter service and 40 km/h
Oxidation evident on wheel rim and web greater
wheelset to be removed. maximum
than 80 mm from the intersection between the
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back or front face and the underside of the rim If found en-route, continue at
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reduced speed with brakes isolated
or removed from service.
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Wheel overheated I combination with thermal Examine defect in the section Not to run until
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cracks before movement to nearest siding wheel has been
at speed nominated by the cleared by the
A class 4 overheating combination with thermal
maintenance officer. maintenance officer.
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cracks classified as Class 3,4 or 5 according to Table
6:1
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Table 12:2 – Overheated painted wheels

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3 Rim Overheated Normal speed

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Paint blistering and discoloration (browning) on web Work out of service

but less than 80 mm from the intersection between
the back or front face and the underside of the rim.
4 Web with paint burn off (Web overheated) If found pre-trip or at a depot the
wheel shall not enter service and
Paint blistering and discoloration (browning on web
wheelset to be removed. Speed 40 km/h
greater than 80 mm from the intersection between
the back or front face and the underside of the rim. If found en-route, continue at maximum
reduced speed with brakes
isolated or remove from service.
5 Wheel overheated in combination with thermal Examine defect in the section Not to run until
cracks before movement to nearest wheel has been
siding at speed nominated by the cleared by the
A class 4 overheating combined with thermal cracks
maintenance officer. maintenance officer.
classified as Class 3, 4 or 5 according to Table 5:1.
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NOTE 1: Overheated low stress wheels may be treated more leniently than conventional wheels (e.g. Class 4 wheel can be
treated as Class 3).

Wheel defects
Code of Practice
13 Tread checks
Tread checks should not be confused with thermal cracks. Tread checks are caused by high axle loads or
poor steering vehicles. Lateral and longitudinal surface traction forces can produce a series of fine
checks on the wheel tread caused by rolling contact fatigue. These are generally inclined at an angle and
most commonly occur near the front face of the wheel and flange where the wear rate is low. Wheels
frequently subjected to sharp curves could have checking approaching a circumferential direction.
Because the checking is at an acute angle to the surface in cross-section it will feel rougher across the
checking in one direction than in the opposite direction.
Wheels should be scheduled for machining if spalling of pieces from the surface has reached the stage
shown in the Figure 13:1 below. These spalls are approximately 1 mm wide.
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Figure 13:1 – Tread checks
Table 13:1 – Tread checks

Class Description Action required Speed restriction
1 Wheel tread checks No action required Not applicable.
Inclined fine lines close together on wheel tread, commonly
on the field side of the wheel. Often found on high axle load
vehicles.
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Wheel defects
Code of Practice
14 Misaligned brake gear

General
The most common occurrence of misaligned brake gear is where the brake block overhangs the side of
the wheel rim. This not only results in uneven wear of the blocks and rapid reduction in block life, but
also in excessive heat input into the outer edge of the tread and rim face. The condition can be
temporary or permanent. Blocks could also wear unevenly against the running face of the flange.
Temporary brake block overhang

Where an overhanging brake block is found and there is no evidence of shouldering on the block, no
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ridges on the tread and no Class 4 thermal cracks, the overhanging block could be a temporary condition
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(see Figure 14:1).
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Consideration shall be given to the lateral float of the wheelset combined with the brake rigging
clearances to determine if the overhang is temporary.
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If bogie inspection indicates that the overhang is temporary, then the vehicle is suitable for service with
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regular block inspections.
On bogies where the brake rigging is rigidly connected laterally there should be no overhanging blocks.
If found, corrective action shall be taken to adjust the rigging and/or replace worn components.
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If there is any evidence of other wheel defects, the vehicle shall be handled in accordance with the
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applicable clauses of this section.

Where non-metallic and/or segmented blocks are used, attention shall be given to the presence of
thermal cracks and skidded wheels.
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If a shoulder has been worn on the edge of the block face, the defect shall be handled as prescribed in
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Section 14.3 below. Note that non-metallic blocks will not necessarily exhibit a definite shoulder as the
overhanging portion tends to break away before achieving a recognisable size.
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Figure 14:1 – Temporary break block overhang

Wheel defects
Code of Practice
Permanent brake block overhang

Where an overhanging block is found and determined to be a permanent fault the vehicle shall be
withdrawn from service until the fault has been corrected. Permanent faults are indicated by evidence
of a shoulder or groove on the block face as shown in Figure 14:2, a ridge on the wheel tread as shown
in Figure 14:3, or Class 4 thermal cracks at the edge of the wheel tread.
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Figure 14:2 – Permanent brake block overhang
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Figure 14:3 – Tread ridge due to block overhang
Note: The tread ridge as shown in Figure 14:3 could also be caused by a wheelset tracking error. In that
case the tread ridge is accompanied by a greater flange wear on the wheel at the opposite end of the
axle.
D
15 Out-of-round wheels
Out-of-round wheels occur where there is excessive variation in the radial measurement of the wheel
tread. The wheel tread circumferential shape could be oval or corrugated but this is generally not
observable to the eye. However, out-of-round wheels produce high impacts when passing over impact
load detectors and produce a characteristic thumping or vibration with train passage.

Wheel defects
Code of Practice
There are four common forms of out-of-round wheels:

(a) Tread defect initiated - Produced when spalls and wheel flats are pounded out during
service.
They will also facilitate the initiation of shattered rims
(b) Wear initiated - Also known as polygonization or wheel corrugations. This type of out-of-
round defect produces a series of corrugation-like nonhomogeneous wear around the
circumference of the wheel. Causes include non-uniform wheel rim hardness, non-uniform
brake application, and torsional oscillation of wheelset in curves or under traction.
(c) Maintenance/machining initiated - This form of out-of-round wheels is produced by any of
the following:
i. An off-centre mounted wheel.
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ii. A new wheel machined off centre.
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iii. An axle with its centre off by a machining error or a worn axle centre.
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iv. Excessive wheel lathe clamping forces on the wheel rim, generating a three
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peak polygon wheel shape.
(d) Manufacture initiated - This form of out-of-round defect concerns cast wheels with
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unmachined tread (Griffin process). Low areas on the tread can be found on those wheels
adjacent to the remnants of each riser on the front face of the wheel web just inside the
rim. The regular spacing of the risers can produce severe vibrations.
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Wheel defects
Code of Practice
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Figure A:1 – Tread line

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Figure A:2 – Flange height

Wheel defects
Code of Practice
13 to 18 mm
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Figure A:3 – Flange angle
Flange angle is measured at any point between 13 -18 mm above the tread line point.
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Figure A:4 – Flange thickness

Flange thickness is generally measured at 10.5 ± 0.5 mm above the tread line point; however it is noted that Queensland Rail
use 16mm ± 0.5 mm above the tread line point.

Wheel defects
Code of Practice
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Figure A:5 – Tread hollowing
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Note that the 3 mm hollow wear limit applies at any point across the tread.
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Wheel defects
Code of Practice
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Figure B:1 - Gauge G-345 (Narrow gauge use only)

Wheel defects
Code of Practice
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Figure B:2 - Gauge G-345/B

Wheel defects
Code of Practice
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Figure B:3 - Gauge 307 – 030

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Wheel defects
Code of Practice
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Figure B:4 – Gauge 17-4-1

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Wheel defects
Code of Practice
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Figure B:5 – Gauge 207 – 661

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Wheel defects
Code of Practice
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Figure B:6 – RISSB Wheel hollow wear gauge

Wheel defects
Code of Practice
Many RTOs utilise wheel inspection technologies such as:

(a) optical systems for the measurement of wheel profile condition;
(b) eddy current and alternating current field measurement (ACFM) techniques for the
detection and quantification of surface cracking; and
(c) ultrasonic-based systems for the assessment of residual stresses, ultrasonic testing of the
wheel rim for the detection of internal discontinuities.
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Many rail networks have installed wheel impact load detectors (WILD) to identify tread defects. Where
these systems are installed and the data is recent, the impact force should be used as the primary
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measure to assess the removal of wheels. Where WILD data does not exist or is not current,
measurement of the physical dimensions of the tread defect is the primary method for assessing the
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removal of wheels. When inspecting the defect there could be components of out of round, which can
increase the impact force to a much higher defect classification than the physical size. This should
always be taken into consideration when classing a tread defect. Refer to Figure 4:1 for an example of a
spall approximately 22 mm in size; however, the actual affected area is approximately 110 mm.
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When measuring defects in Sections 5, 6, 7 and 8 the effects of wheel tread geometry such as that
illustrated in Figure C:1 should be taken into consideration, and a review of available wheel impact data
carried out.
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Actual Defect Size

(A flat that has been
worn and hammered
out in service)
Conspicuous Defect
Size (A spall) - Shall
not be used to rate
defect size
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Figure C:1 – Compound tread defect

Wheel defects
Code of Practice
The length of time a wheel with a tread condition that results in impact loading remains in service may
further alter the tread condition, resulting in increased impact loading. The example shown in Figure C:1
indicates a tread which has started to collapse due to repetitive impact loading. On close inspection the
discolouration reveals a larger defect than that of the spalled area.
Additionally, when reviewing the actual size of a tread defect a straight edge may be used on the tread
defect area, which is rocked back and forth to determine the true affected area. The RIM and RTO shall
agree on limits and removal criteria for impact force levels and the corresponding defect sizes and
duration in service.
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Wheel defects
Code of Practice
A common type of freight wheel condemning gauge is shown in Figure D:1. Sections D.2 to D.5 show
how to use these example gauges. Each Rail Network or RTO may develop their own specific gauge and
application method for measuring critical wheel dimensions. Refer to Section 5 for limiting dimensions.
Refer to Appendix B for gauges applicable to specific rail networks or operations.
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Figure D:2 – Condemning gauge
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Hold the gauge against the rim back as shown in Figures D:2 & D:3 with the long leg pointing to the
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centre of the wheel. A wheel with an acceptable flange height is shown in Figure D:2. If the flange
touches the high flange section of the gauge, the flange is high (greater than 35 mm) relative to the
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tread, as shown in Figure D:3.

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Figure D:2 – Gauging for high flange Figure D:3 - Gauging for high flange
(acceptable) (condemn)

Wheel defects
Code of Practice
Hold the gauge against the rim back, as shown in Figures D:4 & D:5, with the long leg pointing to the
centre of the wheel. If the flange thickness is satisfactory, the gauge short arm, which is marked thin
flange, should not be able to fit over the flange and allow the tip to make contact with the tread area -
refer Figure D:4. Refer to Section 5 for limiting dimensions for thin flange.
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Figure D:4 – Acceptable Gauging for thin flange Figure D:5 - Gauging for thin flange
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Wheel defects
Code of Practice
Hold the gauge so that the edge opposite the high flange mark is flush with the tread surface as shown
in Figures D:6 & D:7. The long leg of the gauge should point away from the centre of the wheel. An
acceptable flange angle is where no part of the gauge above the slot is touching the flange surface as
per Figure D:6. If any part of the gauge above the slot at point 'B' touches the flange surface, this
indicates that the wheel has a steep flange - refer Figure D:7.
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Figure D:6 – Acceptable Gauging for thin flange Figure D:7 Gauging for thin flange
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The Rim Thickness is defined according to Figure 3:1. Hold the gauge on the rim back as shown in
Figure 4:9 with the long leg pointing towards the centre of the wheel. Ensure that the tip of the gauge
long arm is touching the wheel tread area. The scale reading adjacent to the rim back edge at point “A”
is the rim thickness – refer to Figure D:8.
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Figure D:8 – Gauging rim thickness

Wheel defects
Code of Practice
Note: If the back face contains a chamfer, the gauge scale shall be read at the same height as the rim
underside.
Warning gauges (special purpose) may be developed by rail networks or RTOs and used for the
identification of wheels that are approaching the condemning limit but have not reached that limit.
Hold the gauge (1) tight against the rim back face as shown in Figure D:9 and move it downwards until it
touches the front part of the tread. Check the distance between tread and gauge with the feeler (2) at
the position of maximum tread hollowing (hw), wherever this occurs across the tread. Determine the
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value of tread hollowing (hw) with the feeler as follows:
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• Feeler cannot be inserted: hw< 2 mm
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Feeler can be partly inserted: Read the value of hw on the feeler graduation
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• Feeler can be fully inserted: hw> 3 mm
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Figure D:9 – Gauging tread hollowing

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Wheel defects
Code of Practice
The repair guidance provided in Appendix E is informative and therefore not provide comprehensive
guide for the repair of wheels.
The guidance is intended to complement the requirements of AS 7514.
The user is to assess whether the repair guidance provided meets their organisation’s operational
environment and risk profile.
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Thermal cracks shall be rectified by turning to a depth that ensures all cracks are eliminated.
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Where significant cracks are identified, the location of the crack should be marked by the wheel lathe
operator on the rim to allow for inspection to ensure the full extent of the crack has been removed.
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After machining, carry out non-destructive crack detection using, for example, magnetic particles, dye-
penetrant or visual inspection.
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The brake system to be checked for correct operation and the correct type of brake blocks on any
vehicle that is detected with thermal cracks.
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Rectify spalling or shelling by machining to a sufficient depth (3 mm minimum) to completely eliminate

it and carry out crack detection after machining.
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Check the axle bearings and related equipment of a bogie found to have spalled or shelled wheels for
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the effects of vibration.

Remove axle bearings for inspection where Class 4 spalling has occurred.
The tread shall be machined to a minimum of 3 mm below the wheel flat defect area. The heat affected
material shall be removed completely; otherwise further issues requiring further re-profiling are likely to
occur once the vehicle returns into service.
The heat affected material can to some extent be identified by its difference in hardness and that it
could contain cracks. By observing the cutting tool, the sound from it, the chip breaking and the shine
from the turned surface as the tool passes over the damaged tread area, it is often possible to judge
when all the heat affected material has been removed.
If the length of the wheel flat is less than 25 mm then cutter blocks may be used in place of brake blocks
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to restore the wheel to serviceable condition after which normal brake blocks shall be fitted.
Alternatively, trim blocks (blocks with an abrasive layer allowed to remain on vehicle) may be used.
Bogies with wheelsets that have been operating with Class 4 wheel flats shall, due to the vibrations
induced, be thoroughly examined for evidence of loose, misaligned or damaged components,
particularly in relation to axle-boxes and bearing adaptors.

Wheel defects
Code of Practice
Bearings should be removed for inspection after Class 4 wheel flats due to the risk of bearing damage.
For wheels having less than 1 mm depth of build-up on the tread area a cutter block may be used to
restore the wheel to serviceable condition after which a normal brake block shall be fitted.
When rectifying the defect it is important to remove all overheated wheel tread material by machining
to a depth (3 mm minimum) sufficient to completely eliminate the defect.
Unless the cause of the incident is obvious, e.g. a not released handbrake/parking brake, any vehicle
that is found with any amount of scaling on the tread should undergo a single car brake test as soon as
possible.
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The axle bearings and related equipment of a bogie found to have operated with Class 4 scaling on its
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wheels shall be checked for the effects of vibration.
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Axle bearings shall be removed for inspection where Class 4 scaling has occurred.
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If the scale height can be reduced by chipping or grinding before movement of vehicle the speed
restrictions given in Table 8:1 can be moderated according to appropriate subclass (i), (ii) or (iii).
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Tread and flange wear conditions shall be repaired by reprofiling the wheelset.
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Marks on the flange or tread shall be corrected by machining unless they meet the following criteria:
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(a) Less than 25 mm in length and width.

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(b) Located in central region of wheel tread (shaded area in Table 1 for thermal cracks).
(c) Depth less than 3 mm.
(d) Any raised metal around the marks is less than 1 mm above the original tread surface.
Chips on the outer edge of the wheel tread greater than 2 mm in depth or 25 mm in length shall be
removed by machining. Any local rollover shall be treated as a rolled edge.
Marks elsewhere on the wheels less than 3 mm deep may be locally ground to remove sharp edges.
Wheels with scrapes, dents or gouges that cannot be corrected by either of these methods shall be
condemned.
Derailed wheelsets (in the absence of other specific criteria, those which have been involved in a
derailment where the wheelset is derailed for more than 60 metres, or at greater than 15 km/h, or
other abnormal conditions) shall be checked for distortion by using a three point test of the rim to rim
distance, or by measuring the run-out as the axle is revolved between centres or on its own bearings –
refer AS 7517 for tolerance requirements. If a wheel is found to be distorted it shall be condemned.
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Overheated wheels may be repaired by machining to remove any visible surface damage and then a
further 20 mm off the diameter (10 mm off the rim thickness). Wheels should be condemned if they are
at the last turn diameter.

Wheel defects
Code of Practice
Alternatively, wheels that are severely overheated should be thoroughly inspected for deformation
and/or change of residual stress state. In case large tensile stresses have been formed in the wheel rim,
the wheel shall be condemned.
Various techniques and methods are available for assessing the residual stress levels within the wheel
rim. However, the limits and instructions outlined by the specific operator/maintainer shall be adhered
to. If there is any doubt as to the soundness of the wheel, the wheel shall be condemned. Note that a
procedure for non-destructive assessment of residual stresses in wheels is outlined in EN 13262.
Checking shall be removed by machining to a depth sufficient to ensure all defects are removed.
Magnetic particle inspection or dye penetrant may be used to ensure that the cracks have been
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Wheelsets with tread defect or wear initiated out-of-round wheels should be machined to the
tolerances given in AS 7517.
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Wheelsets with maintenance initiated out-of-round wheels should have the off-centre defective
component replaced and the wheelset checked against the tolerances given in AS 7517.
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Wheel defects
Code of Practice
The following referenced documents are used by this Code of Practice for information only:
• EN 13262 Railway Applications - Wheelsets and Bogies - Wheels - Product Requirement.
• Field Manual of the AAR Interchange Rules.
• FreightCorp Examiner’s Pocket Field Manual EFR.0004 dated September 1996.
• Guidance on Railway Wheelset Tread, Gauging and Damage” published by the UK Rail
Safety and Standards Board (UK RSSB GM/GN2497)
• Interfleet report ITLR-T22393-001 "Development of a Wheel Tread Hollowing Gauge".
• International Heavy Haul Association "Guidelines to Best Practices for Heavy Haul Railway
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Operations: Wheel and Rail Interface Issues".
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• John Holland Rail Procedure Rail-Plant-2-100-12 "Rail Wheel Inspection".
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Pacific National Train Inspection Manual TIM 03-08_04 "Wheel Profile & Tread Condition".
Queensland Rail Specification SAF/SPC/0012/RSK "Wheel Defect Identification &
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Rectification".
• RailCorp ESR 0330 "Wheel Defect Manual".
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• RCP-2304 "Identification and Classification of Wheel Defects", Draft Volume 5 from the
Code of Practice for the Defined interstate rail network.
• ROA Manual of Engineering Standards and Practices.
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• TransAdelaide "Rail Car Wheel Inspection Manual".

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• UIC "Atlas of Wheel and Rail Defects".

• V/Line Procedure VEPR-009 "Wheel Management Strategy for Locomotive".
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• V/Line Procedure VEPR-011 "Rail Wheel Defects, Inspection and Rectification".

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ABN 58 105 001 465
For information regarding s product developed by RISSB contact:

Brisbane Office
Level 4, 15 Astor Terrace
Brisbane, QLD, 4000
Melbourne Office
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Level 4, 580 Collins Street,
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Melbourne, Vic, 3000
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PO Box 518 ub Pr fec
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Spring Hill, QLD, 4004
T +61 7 3724 0000

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E Info@rissb.com.au
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John Holland Metro Trains PTA

Rail Industry Safety and Standards Board

Keeping Codes of Practice up-to-date

518, Spring Hill, QLD 4004, Australia.

RISSB product can be found at: http://www.rissb.com.au/products/.

Wheel defects Page 2 of 61

Document Title Version Date

Wheel defects 2.0 29 July 2020

Clarifications and correction of

1.1 15 Jul 2013 Errata – missing Appendix A Wheel

1.0 3 December 2012 All First Publication

Rail Industry Safety and Standards Board

Wheel defects Page 3 of 61

Tyred wheels ................................................................................................................ 15

5 Thermal cracks ............................................................................................................................ 15

8 Scaled wheels ............................................................................................................................. 22

9 Arrises and other flange defects................................................................................................. 24

Cracked or broken flange ............................................................................................. 33

Wheel defects Page 4 of 61

E.1 General ......................................................................................................................... 57

E.2 Thermal cracks ............................................................................................................. 57

E.5 Scaled wheels ............................................................................................................... 58

E.7 Tread and flange wear ................................................................................................. 58

Wheel defects Page 5 of 61

relevant Railway Infrastructure Manager (RIM).

Wheel defects Page 6 of 61

The following definitions are specific to this Code:

Wheel defects Page 7 of 61

(h) heat check

outer portion of a wheel that interfaces with the rail

(q) rim width

distance between the faces of the rim

known as shelled tread

Wheel defects Page 8 of 61

(w) shattered rim

(ee) wheel flat

Wheel defects Page 9 of 61

Table 2:1 - Wheel defect classification and definitions

(b) Defects caused by heat generation from sliding:

iii. Scaled wheels - see Section 8.

(c) Defects caused by wear, flow, and improperly steering bogies:

(e) Defects that cause or result from impacts:

Wheel defects Page 10 of 61

(f) Defects associated with braking:

Figure 2:3 – Wheel shape definition

Wheel defects Page 11 of 61

Wheel defects Page 12 of 61

Figure 3:1 – Location of limiting dimensions

d: Wheel diameter l: Rim width e: Flange thickness¹

Wheel defects Page 13 of 61

Wheel rim thickness

Permissible variation in wheel diameter

Wheel defects Page 14 of 61

Limiting tread and flange dimensions