ANSI/AGMA 9009- D02

(Revision of AGMA 510.03)

AMERICAN NATIONAL STANDARD

Flexible Couplings - Nomenclature for

Flexible Couplings
ANSI/AGMA 9009- D02
 Flexible Couplings - Nomenclature for Flexible Couplings
American ANSI/AGMA 9009--D02
National (Revision of AGMA 510.03)
Standard Approval of an American National Standard requires verification by ANSI that the require-
ments for due process, consensus and other criteria for approval have been met by the
standards developer.
Consensus is established when, in the judgment of the ANSI Board of Standards Review,
substantial agreement has been reached by directly and materially affected interests.
Substantial agreement means much more than a simple majority, but not necessarily una-
nimity. Consensus requires that all views and objections be considered, and that a
concerted effort be made toward their resolution.
The use of American National Standards is completely voluntary; their existence does not
in any respect preclude anyone, whether he has approved the standards or not, from
manufacturing, marketing, purchasing or using products, processes or procedures not
conforming to the standards.
The American National Standards Institute does not develop standards and will in no
circumstances give an interpretation of any American National Standard. Moreover, no
person shall have the right or authority to issue an interpretation of an American National
Standard in the name of the American National Standards Institute. Requests for interpre-
tation of this standard should be addressed to the American Gear Manufacturers
Association.
CAUTION NOTICE: AGMA technical publications are subject to constant improvement,
revision or withdrawal as dictated by experience. Any person who refers to any AGMA
Technical Publication should be sure that the publication is the latest available from the
Association on the subject matter.
[Tables or other self--supporting sections may be quoted or extracted. Credit lines should
read: Extracted from ANSI/AGMA 9009--D02, Flexible Couplings -- Nomenclature for
Flexible Couplings, with the permission of the publisher, the American Gear
Manufacturers Association, 1500 King Street, Suite 201, Alexandria, Virginia 22314.]

Approved June 27, 2002

ABSTRACT
This standard presents the nomenclature common to flexible couplings as used in mechanical power transmis-
sion drives. It does not address nomenclature for flexible shafts, quill shafts, universal joints or devices which
exhibit slip such as clutches, fluid couplings, magnetic couplings or torque converters. The standard was pre-
pared to reduce the language barriers that arise between designers, manufacturers and users when attempting
to designate or describe various types of flexible couplings and their elements.

Published by

American Gear Manufacturers Association

1500 King Street, Suite 201, Alexandria, Virginia 22314
Copyright  2002 by American Gear Manufacturers Association
All rights reserved.

No part of this publication may be reproduced in any form, in an electronic

retrieval system or otherwise, without prior written permission of the publisher.

Printed in the United States of America

ISBN: 1--55589--796--7

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AMERICAN NATIONAL STANDARD ANSI/AGMA 9009--D02

Contents
Page
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv
1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 Normative references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
3 Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
4 Coupling definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
5 Bores in hubs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
6 Keys, keyways and keyseats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
7 Shaft relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
8 Coupling physical properties and other characteristics . . . . . . . . . . . . . . . . . . . . . 6
9 Terms used in coupling selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
10 System terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
11 General terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Figures

1 Shaft relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2 Torsional stiffness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3 Damping coefficient . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4 Example of pulsating torque . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5 Example of reversing torque . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6 Static unbalance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
7 Couple unbalance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
8 Dynamic unbalance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Tables

1 Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

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ANSI/AGMA 9009--D02 AMERICAN NATIONAL STANDARD

Foreword
[The foreword, footnotes and annexes, if any, in this document are provided for
informational purposes only and are not to be construed as a part of ANSI/AGMA Standard
9009--D02, Flexible Couplings -- Nomenclature for Flexible Couplings.]
This Standard was prepared to reduce the language barriers that arise between designers,
manufacturers, and users when attempting to designate or describe various types of flexible
couplings and their elements.
The first draft copy of AGMA 510.01 was prepared by the Flexible Coupling Nomenclature
Committee in October, 1963. It was accepted as an AGMA Standard on July 9, 1965.
AGMA 510.01 was editorially changed and approved as AGMA 510.02 in August 1969.
AGMA 510.03 was approved in October, 1983. The revised standard contained an
improved clarity in definitions, simplification of nomenclature, addition of coupling physical
property terms and units including SI Units, and introduction of an axial travel term for
couplings.
ANSI/AGMA 9009--D02 is a revision of AGMA 510.03, and was approved by the AGMA
membership in May 2001. It was approved as an American National Standard on June 27,
2002. This revision includes additional nomenclature from standards developed since the
previous revision.
Suggestions for improvement of this standard will be welcome. They should be sent to the
American Gear Manufacturers Association, 1500 King Street, Suite 201, Alexandria,
Virginia 22314.

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AMERICAN NATIONAL STANDARD ANSI/AGMA 9009--D02

PERSONNEL of the AGMA Flexible Couplings Committee

Chairman: Glenn Pokrandt . . . . . . . . . . . . . . . . . . . . . . The Falk Corporation

Vice Chairman: James Paluh . . . . . . . . . . . . . . . . . . . . Boston Gear/Ameridrives Gear Coupling Ops.

ACTIVE MEMBERS

D.A. Boccio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Boston Gear/Ameridrives Gear Coupling Ops.

T. Cain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lucas Aerospace
D.E. Crysler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T.B. Wood’s, Inc.
D.B. Cutler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rexnord Coupling Division
P.J. Dixon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Metal Improvement Company
A. Hasebrock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Flender Corporation
T. Hewitt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rexnord Coupling Division
D. Hindman . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rexnord Elastomer Products Division
J.W. Mahan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lovejoy, Inc.
J.R. Mancuso . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Kop--Flex, Inc./Emerson Power Transmission Corp.
S.L. Pearson . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mobil Oil Corporation
R.S. Post . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rexnord Coupling Division
J. Sherred . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Renold, Inc.
R.G. Thompson . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T.B. Wood’s, Inc.
R. Whitney . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Riverhawk Company

ASSOCIATE MEMBERS

D. Drechsler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Huffman Corporation

K.H. Hoelmer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Xtek, Incorporated
V. Ivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Xtek, Incorporated
D. Lindsay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Emerson Gearing/Morse, Browning, USEM
L. Lloyd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lufkin Industries, Inc.
R.E. Munyon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Kop--Flex, Inc./Emerson Power Transmission Corp.
M.A. O’Neill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Riverhawk Company
D. Reynolds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rockwell Automation/Dodge
E.I. Rivin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Wayne State University
T. Van Cleave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Xtek, Incorporated
W. Welsch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Metal Improvement Company

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ANSI/AGMA 9009--D02 AMERICAN NATIONAL STANDARD

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AMERICAN NATIONAL STANDARD ANSI/AGMA 9009--D02

American National Standard -- 2 Normative references

Flexible Couplings -- The following documents contain provisions which,

through reference in this text, constitute provisions of

Nomenclature for the standard. At the time of publication, the editions

were valid. All publications are subject to revision,
Flexible Couplings and the users of this manual are encouraged to
investigate the possibility of applying the most recent
editions of the publications listed.

ANSI/AGMA 9000--C90, Flexible Couplings --

Potential Unbalance Classification
1 Scope
ANSI/AGMA 9002--A86, Bores and Keyways for
Flexible Couplings (Inch Series)
1.1 Applicability
ANSI/AGMA 9004--A99, Flexible Couplings --
This standard provides nomenclature common to Mass Elastic Properties and Other
flexible couplings and their application as used in Characteristics
mechanical power transmission drives.
1.2 Exceptions
The following coupling types are not included in this 3 Symbols
standard:
-- flexible shaft; The symbols used in this standard are shown in
-- quill shaft; table 1.

-- universal joint; NOTE: The symbols and terms contained in this

document may vary from those used in other AGMA
-- devices which exhibit slip such as clutches, standards. Users of this standard should assure them-
fluid couplings, magnetic couplings and torque selves that they are using these symbols and terms in
converters. the manner indicated herein.

Table 1 -- Symbols
Units Where first
Symbol Definition
SI (inch) used
AD Damping energy during one cycle N--m lb--in Eq 2
AE Elastic deformation energy N--m lb--in Eq 2
dT Rate of change in torque Nm lb--in Eq 1
dθ Rate of change in torsional deflection radians radians Eq 1
F Force N lb Eq 3
J Polar mass moment of inertia N--m--s 2 lb--in--s2 8.4
k Torsional stiffness Nm/radian lb--in/radian 8.5
M Mass kg slug 8.1
Ra Arithmetic average of surface finish mm min 11.5.1
Rq Root--mean--square of surface finish mm mm 11.5.2
r Distance m in Eq 3
T Torque Nm lb--in Eq 3
(continued)

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ANSI/AGMA 9009--D02 AMERICAN NATIONAL STANDARD

Table 1 (concluded)
Where first
Symbol Definition Units
used
W Weight kg lbf 8.2
WR2 Coupling flywheel effect, also known as polar kg--m2 lb--in2 8.3
weight moment of inertia
ψ Damping coefficient -- -- -- -- 8.7.2

4 Coupling definitions and coefficient of friction between the mating sur-

faces. Examples of mechanical elements are gear,
grid and chain.
4.1 Rigid coupling
4.2.1.2 Metallic element
A mechanical shaft connector designed to transmit
torque without slip and will transmit axial/thrust force. A form of flexible element which accommodates
This coupling will not accommodate misalignment. It misalignment by material deflection of a metal
can be flange type, sleeve type, solid or split. member. These elements are very much like springs
in that they have a free form shape and will resist a
4.2 Flexible coupling change in shape with a reaction force. Examples of
A mechanical shaft connector designed to transmit metallic elements are contoured diaphragm,
torque without slip, and to accommodate misalign- convoluted diaphragm, disc, springs and bellows.
ment and sometimes axial travel between driving 4.2.1.3 Elastomeric flexible element
and driven machine members. Some flexible
These flexible elements are characterized by the use
couplings are designed to also transmit axial/thrust
of an elastomer. There are many types of elastomer-
force.
ic elements which accommodate misalignment
4.2.1 Flexible element through varying degrees of material deflection and
sliding motion. Some single flexible element designs
The part of a coupling which provides flexibility.
may act as a double engagement coupling. Reac-
Various flexible element designs utilize a number of
tion forces of elastomeric flexible elements are
operating principles to provide flexibility. The design
determined by element configuration, material stiff-
of this element determines the character of the
ness, coefficient of friction and torque. They can be
coupling in terms of reaction forces, dynamics and
categorized into two general types, compression
reliability. For this standard, common flexible
and shear, based upon the way torque is transmitted
element types have been grouped into three major
through the flexible element. Because of the great
categories which are defined below. Note that the
variety of designs, some actually fit both categories
character of a particular flexible element type may
in varying degrees.
cross or fall outside the definitions below. Also note
the properties of flexible elements themselves are 4.2.1.4 Others
not covered in this standard. The reader is directed There are other types of flexible elements that
to the appropriate coupling manufacturers for infor- accommodate misalignment through various other
mation on the properties of a particular type of methods and/or combinations of the previously
flexible element. mentioned types, such as slider block, pin and
4.2.1.1 Mechanical element bushing, and composites.
4.3 Single acting (single engagement)
A form of flexible element which accommodates
misalignment by sliding or rolling on mating A coupling where the corrective movement for
surfaces. These parts normally require lubrication. misalignment takes place in a single plane normal to
These elements do not have a free state position. the shaft axis (contains a single flex element). Single
They can be at rest at any combination of axial and acting metallic flexible element and mechanical
angular positions within their flexible capability. flexible element designs can accept only angular
Mechanical elements resist change in axial and misalignment and axial displacement. Elastomeric
angular position mainly as a function of shaft torque flexible elements and pin and bushing designs can

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AMERICAN NATIONAL STANDARD ANSI/AGMA 9009--D02

accept both parallel and angular misalignment and 4.10 Diametral clearance (tip or root clearance)
some designs may accept axial displacement. The clearance between the piloting diameters of the
coupling’s external and internal teeth.
4.4 Double acting (double engagement)
4.11 Electrically insulated coupling
A coupling where the corrective movement for
misalignment takes place in two spaced planes Coupling designed to prevent the flow of electrical
normal to the shaft axis. Double acting metallic current from one shaft to the other through the
flexible element and mechanical flexible element coupling.
designs will accept parallel offset misalignment, 4.12 Limited--end--float coupling
angular misalignment and axial displacement.
Coupling designed to limit the movement of the shaft
Elastomeric flexible element and pin and bushing
ends with respect to each other where one shaft has
couplings may require additional centering devices
no thrust bearing for centering. A limited--end--float
to support long floating shaft arrangements.
design is commonly used in couplings for sleeve--
4.5 Half coupling bearing motors.
4.13 Coupling designs
Consists of all the components of the couplings
attached to, and supported from one shaft. It Coupling designs can either be standard, modified
includes an appropriate portion of the spacer standard or special.
assembly in the case of a double engagement 4.13.1 Standard couplings
coupling, or of the flexing element of a single Flexible couplings that are pre--engineered and
engagement coupling. consistent with the individual manufacturer’s pub-
lished catalogue data. This data may include
4.6 Backlash
physical dimensions, ambient conditions, selection
The circumferential clearance in the flexible ele- criteria, maintenance requirements and perfor-
ment. In some couplings, it provides misalignment mance data such as load, speed, misalignment, and
capability and ease of assembly. axial travel.
4.13.2 Modified standard couplings
4.7 Batch--lube coupling
Flexible couplings that have one or more of the
A coupling that is designed to be lubricated by a components modified by the manufacturer for a
periodically changed charge of grease or oil. particular application.
4.8 Continuous--lube coupling 4.13.3 Special couplings
Flexible couplings that are designed and
A coupling that is designed to be lubricated by a
manufactured for specific applications.
continuous external supply of oil directed through the
gear mesh. 4.14 Types of flexible couplings

4.8.1 Anti--sludge design Some of the most common types of flexible

couplings are listed below.
A coupling designed to minimize sludge--gathering 4.14.1 Chain coupling
pockets in continuously lubricated couplings.
A chain coupling consists of two hubs with sprocket
4.8.2 Flooded mesh (dammed) coupling teeth which engage or mesh with a strand of chain.
4.14.2 Compression elastomeric coupling
A continuously lubricated coupling in which the gear
meshes are completely submerged in oil during A coupling which transmits torque between the two
normal operation. coupling hubs by an elastomeric flexible element
which is placed into compression between axially
4.9 Crown diameter extending lugs or pockets of the two hubs.

The pilot between the internal teeth (sleeve) and the 4.14.3 Shear elastomeric coupling
external teeth of gear couplings. This diameter could A coupling which transmits torque between the two
be the major (outside) diameter or minor (root) hubs of the coupling by an elastomeric flexible
diameter of the external gear teeth. element which is placed into shear.

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ANSI/AGMA 9009--D02 AMERICAN NATIONAL STANDARD

4.14.4 Diaphragm coupling 4.14.12 Sliding block

A coupling consisting of one or more flexible A sliding block coupling consists of two jawed
elements that are attached to the outside diameter of (slotted) hubs engaged with a mating center
one flange, and transfer torque through the dia- member. Sliding block is the preferred term for
phragm to its inside diameter attachment (a spacer Oldham.
or another flange). 4.14.13 Spring coupling

4.14.5 Disc coupling Provides the flexible link between two hubs, one
attached at either end of the spring.
Consists of one or more flexible elements that are
4.14.14 Bellows coupling
alternately attached with bolts to the opposite
flanges, and transfers torque through the element A thin cylindrical metal bellows with hubs attached at
tangentially through the bolts. either end. Bellows can be single or multiple
thickness. Hubs can be permanently attached or
4.14.6 Gear coupling clamped to the bellows.
A gear coupling consists of hubs with external gear 4.14.15 Beam coupling
teeth, which mesh with internal gear teeth on the A single or multiple helix cut in a hollow bar forms a
sleeve or sleeves. Gear couplings transmit torque curved beam that becomes the flexing element.
and accommodate angular misalignment, parallel Hubs are integral or attached to the flexible section.
offset (double engagement), and axial displacement
4.14.16 Composite coupling
by relative rocking and sliding motion between
mating, profiled gear teeth. Can be any of the prior types made from composite
materials.
4.14.7 Marine style coupling
4.15 Coupling components
A coupling which has the flexible elements on the 4.15.1 Hub
removable center section.
The coupling component which is machined for
4.14.7.1 Marine style gear coupling mounting on a shaft.

A gear coupling which has the external gear teeth on 4.15.1.1 Gear hub (flex hub)
the spacer and the internal teeth in the sleeves. A gear coupling component with external teeth.

4.14.8 Reduced moment coupling 4.15.1.2 Rigid hub

A hub that does not accept misalignment.
A reduced moment coupling locates the half--
coupling effective center of gravity (generally the 4.15.1.3 Flexible hub
flexible element) closer to the connected equipment A hub that accepts misalignment.
bearing to reduce the overhung moment.
4.15.2 Sleeve
4.14.9 Floating shaft coupling A gear coupling component with internal teeth.
Two single acting couplings attached to a floating 4.15.3 Spacer
center shaft. A removable center member that provides a
specified axial shaft separation.
4.14.10 Grid coupling
4.15.3.1 Spacer length
Two flanged hubs with slots or grooves in the
The length of the spacer that may or may not be
flanges, connected by a serpentine mechanical
dimensionally equal to the distance between the
flexible element.
shaft ends.
4.14.11 Pin and bushing coupling 4.15.4 Floating shaft center assembly
A pin and bushing coupling consists of two flanged The removable center member supported by the
hubs with pins on one flanged hub fitting into flexible elements and may or may not include the
bushings in the mating flanged hub. flexible elements.

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AMERICAN NATIONAL STANDARD ANSI/AGMA 9009--D02

4.15.5 Flexible element 5.1.2 Maximum bore

The part of a coupling which provides flexibility (see The largest bore for a specified hub diameter,
4.2.1). consistent with the torque rating and keyway depth
(if any) of the coupling.
4.15.6 Adapter plate
5.1.3 Solid hub
An adapter plate, also known as a solo plate, is an A solid hub has no bore.
auxiliary device required to rigidly hold in alignment
5.1.4 Straight (finished) bore
the flexible element of the coupling to allow solo
operation of the driver without the necessity of A concentric axial cylindrical hole manufactured to
dismounting the coupling hub. dimensional tolerances and surface finish
appropriate for mounting.
4.15.7 Moment simulator
5.1.5 Tapered bore
An auxiliary device required to simulate the moment
A concentric axial conical hole manufactured to
of the coupling portion that is mounted to the driving
dimensional tolerances and surface finish
machine. A moment simulator may also be designed
appropriate for mounting.
to serve as an adapter plate.
5.1.6 Rough bore
4.15.8 Hardware
A centrally located axial hole produced with dimen-
The nuts, bolts, washers, etc., which are used to sions and tolerances in accordance with the practice
attach the various coupling components together. of each manufacturer, and is not appropriate for
mounting or indicating during rebore.
4.15.8.1 Body bound bolts (body fitted)
5.1.7 Mandrel bore
The coupling bolts used to connect joints that
A finished concentric axial hole produced without
transmit torque. Body bound bolts have a slight
keyway, with dimensions and tolerances in
clearance fit to the flange bolt hole and no threads in
accordance with the practice of each manufacturer,
the shear plane. These bolts may be used for
and is used during manufacture or to customer
piloting coupling components.
specifications for indicating during rebore.
4.15.9 Pilots (rabbets/spigots/registers) 5.1.8 AGMA standard bore
A surface that positions a coupling component, A finished hole produced with dimensions and
subassembly or assembly. tolerances as established by ANSI/AGMA
9002--A86.
4.16 Gap
5.1.9 Non--standard bore
The axial distance between two faces that properly
A finished hole produced to dimensions and toler-
locates the coupling assembly and may be used
ances specified by the customer or the manufacturer
during the alignment procedure.
which does not comply with ANSI/AGMA 9002--A86.
5.1.10 Spline bore
A series of axial parallel slots formed internally in the
5 Bores in hubs bore and mating with corresponding grooves cut in a
shaft. The most common splines conform to
5.1 Hub bore standards published by organizations such as SAE,
ISO and DIN. The splines can be in the form of
Bores are cylindrical or conical holes in hubs of involutes or straight parallel sides.
couplings with axes coincident with the rotational
5.2 Hub--to--shaft fits
axis of the coupling.
5.2.1 Clearance fit
5.1.1 Nominal bore
ANSI/AGMA 9002--A86 designates a condition
A commonly used term to identify the basic bore size where the hub bore diameter is equal to (depending
without tolerance. on size) or larger than the shaft diameter.

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ANSI/AGMA 9009--D02 AMERICAN NATIONAL STANDARD

5.2.2 Interference fit 7.2.1 Parallel offset misalignment

ANSI/AGMA 9002--A86 designates a condition Parallel offset misalignment exists when the two
where the hub bore diameter is equal to (depending shafts are not coaxial, but their axes are parallel.
on size) or smaller than the shaft diameter.
7.2.2 Angular misalignment
5.2.3 Transitional fit
The minor angle between two shaft centerlines when
A condition where the shaft and bore tolerances the two shafts are not coaxial, and their axes are not
result in a range of fits which can be either clearance parallel.
or interference.
7.3 Axial relationships
7.3.1 Distance between shaft ends (DBSE,
BSE, BE)
6 Keys, keyways and keyseats
The distance from the face of one shaft to the face of
6.1 Key the next shaft.
7.3.2 Axial displacement (end float)
A mating torsional load transmitting member placed
in a groove in both shaft and hub. A change in the gap between the shaft ends from
6.2 Keyway their position when the coupling was installed.

The axial groove in the hub that holds the key in the
proper location.
8 Coupling physical properties and other
6.3 Keyseat characteristics
The axial groove in the shaft that holds the key in the
proper location. 8.1 Mass, M

6.4 Standard keyways A measure of the inertia of a body. It is the property of

a body which causes resistance to a change in
Standard keyways are produced in a hub to dimen- velocity. Mass is expressed in terms of slugs in the
sions and tolerances as established by ANSI/AGMA English system and kilograms in the metric system.
9002--A86. See ANSI/AGMA 9004--A99, annex J.
6.5 Non--standard keyways 8.2 Weight, W
Non--standard keyways are produced in a hub to The effect of an acceleration (typically gravity) acting
dimensions and tolerances specified by the custom- on the mass of a body. Weight is expressed in terms
er or the manufacturer which does not comply with of pounds force in the English system. In the metric
ANSI/AGMA 9002--A86. system, mass is generally reported instead of
weight. See ANSI/AGMA 9004--A99, annexes A
and J.

7 Shaft relationships 8.3 Coupling flywheel effect, WR2

Flywheel effect (also known as polar weight moment
Shaft relationships are illustrated in figure 1. of inertia) is a measure of the weight distribution
relative to the rotational axis. WR2 is the product of
7.1 Aligned shafts
the weight of the coupling times the square of the
When aligned, the two shafts are coaxial. radius of gyration. The radius of gyration is the
radius at which the mass of the part (coupling) can be
7.2 Misaligned shafts
considered concentrated.
Shafts are misaligned when their axes are not
8.4 Polar mass moment of inertia, J
coaxial. This condition can be the result of parallel
offset misalignment, angular misalignment, or a The resistance to rotational acceleration or decel-
combination of the two. eration. See 4.2 of ANSI/AGMA 9004--A99.

6
AMERICAN NATIONAL STANDARD ANSI/AGMA 9009--D02

Alignment

Axial displacement

Parallel offset
misalignment

Angular misalignment

Generally misalignment encountered is a combination of the above

three conditions (axial displacement + parallel offset + angular)
Figure 1 -- Shaft relationships

8.5 Torsional stiffness, k T

The rate of change in torque with respect to the
torsional deflection about its axis of rotation (see
figure 2). For some types of couplings, torsional
stiffness may vary due to operating or environmental
conditions. It is expressed as:

k = dT (1)
dθ
where dT
k is torsional stiffness, Nm/radian
(lb--in/radian); θ
dθ
dT is the rate of change in torque, Nm (lb--in);
dθ is the rate of change in torsional deflection,
radians. Figure 2 -- Torsional stiffness

7
ANSI/AGMA 9009--D02 AMERICAN NATIONAL STANDARD

8.6 Shaft penetration factor 8.9 Axial stiffness

The percentage of the shaft length within the A measure of a coupling’s resistance to axial
confines of the hub that is assumed to be free from displacement.
restraint at the shaft--hub interface. This is used in 8.10 Radial or lateral stiffness
calculating torsional stiffness of the shaft--hub A measure of a coupling’s resistance to parallel
interface. offset.
8.7 Damping 8.11 Coupling reaction force
The absorption or dissipation of oscillatory energy. A coupling’s reaction force is its resistance to
Damping may be necessary to limit the buildup of displacement.
transient or steady--state resonant oscillations in a 8.12 Coupling half weight
system. A coupling is normally mounted on two separate
8.7.1 Damping ratio (factor of critical damping) equipment shafts, and each shaft supports a portion
of the total coupling weight. The portion supported at
The ratio of the actual damping coefficient to the
each end is called the half weight. If the coupling is
critical damping coefficient. The critical damping
identical at both ends, the half weight is exactly half
coefficient is a measure of the minimum damping
of the coupling weight. If the coupling is heavier at
that will allow a displaced system to return to its initial
one end, the half weight is higher at that end than at
position without oscillation.
the other.
8.7.2 Damping coefficient, ψ 8.13 Half coupling effective center of gravity
The ratio of the damping energy during one cycle to The location at which the weight of the half coupling
elastic deformation energy with respect to mean can be considered to be concentrated. The half
position (see figure 3). coupling effective center of gravity is referenced
from the equipment shaft end, with a positive
AE location being beyond the shaft end and a negative
AD location being within the shaft.
8.14 Axial natural frequency
The natural frequency of the mass of the floating
Torque

spacer element supported by the flexible elements

acting as axial springs.
8.15 Coupling lateral natural frequency
The speed of a coupling in a rotating system, such
Torsional deflection that any change in speed results in a reduction in the
Figure 3 -- Damping coefficient lateral displacement. The system lateral natural
frequency may not be the same as the coupling
A lateral natural frequency. See ANSI/AGMA
ψ= D (2) 9004--A99 for calculation methods.
AE
where
9 Terms used in coupling selection
ψ is the damping coefficient;
The following terms are used in the size selection of
AD is the damping energy during one cycle a flexible coupling. Coupling manufacturers deter-
(elliptical area); mine which terms are used for their particular
AE is the elastic deformation energy (triangular couplings. Coupling size is the manufacturer’s
area). means of expressing basic coupling dimensions.
8.8 Angular stiffness (bending stiffness) 9.1 Torque rating terms
A measure of how much force or bending moment is 9.1.1 Coupling rating
required to angularly misalign a coupling to a Torque capacity at rated misalignment, axial dis-
specified angle while under torque load. placement and speed.

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AMERICAN NATIONAL STANDARD ANSI/AGMA 9009--D02

9.1.2 Continuous torque rating 9.2.4 Coupling installation alignment

recommendation
The manufacturer’s value of the torque capability of
the coupling utilizing a combination of speed, The alignment value supplied by the coupling
misalignment and axial displacement. manufacturer. However, the rotating equipment
supplier’s recommendations may differ and should
9.1.3 Peak torque rating be followed as long as it does not exceed the
coupling rating during operation.
The rating which corresponds to the material yield
strength or to a limited number of uni--directional 9.3 Operating torque terms
cycles utilizing a combination of speed, 9.3.1 Normal (steady state) operating torque
misalignment and axial displacement. The torque which the coupling is to transmit during
9.1.4 Momentary torque limit continuous operation.
9.3.1.1 Constant torque
The momentary torque limit is that which corre-
sponds to a minimum factor of safety of 1.0 with A torque with minimum oscillation.
respect to the component’s material yield strength 9.3.1.2 Cyclic torque
utilizing a combination of speed, misalignment and The part of the torque that oscillates.
axial displacement. The coupling may experience
damage at this limit. 9.3.1.2.1 Pulsating (one--way) torque
Torque that is cyclic but does not pass through zero
9.2 Misalignment terms (see figure 4).
9.2.1 Maximum continuous misalignment

The maximum misalignment (combined angular and

parallel offset) the coupling is able to tolerate for
unlimited periods. This can be expressed either of
two ways:
Torque

-- as a single value, while simultaneously sub-

jecting the coupling to rated speed, continuous
rated torque and maximum continuous axial
displacement; or

-- as an interrelated function of speed, torque 0

Time
and axial displacement.
Figure 4 -- Example of pulsating torque
NOTE: For certain types of couplings, particularly those
with elastomeric elements or inserts, the coupling 9.3.1.2.2 Reversing (alternating) torque
continuous ratings may also be a function of the operat-
ing temperature and the required life of the elements or Torque that is cyclic and passes through zero (see
inserts. figure 5).

9.2.2 Coupling rated no load misalignment

(static misalignment)

The misalignment permitted at non--operating condi-

tions (no speed, no torque, and defined axial
displacement) that will not damage any coupling
Torque

component. 0
Time
9.2.3 Transient misalignment limit

The misalignment which the coupling can accommo-

date during unusual or short term operation without
damage. Figure 5 -- Example of reversing torque

9
ANSI/AGMA 9009--D02 AMERICAN NATIONAL STANDARD

9.3.2 Transient torque be different for operating and non--operating

conditions. This temperature may differ from the
A torque which the coupling is subjected to during
ambient temperature in the vicinity of the coupling.
unusual, or short term operation. Conditions which
produce transient torques are: short circuit torques, 9.8.2 Minimum allowable temperature
electric motor start--ups, process upsets, torque The lowest temperature for which the manufacturer
amplification conditions, etc. The transient torque has designed the coupling. This temperature may
would be compared to the coupling peak torque be different for operating and non--operating condi-
rating or coupling momentary torque limit. tions. This temperature may differ from the ambient
9.3.2.1 Torque amplification factor (TAF) temperature in the vicinity of the coupling.

The transient torque divided by normal operating 9.9 Transmitted axial force
torque. This is normally used in coupling selections The axial force transmitted through the coupling
for rolling mill applications. from one shaft to the other, and is a function of the
resistance to deflection of the flexible element or the
9.3.2.2 Short circuit torque
sliding friction of the gear teeth.
An estimated torque value supplied by the electrical
9.10 Speed considerations
machinery manufacturer.
Manufacturers rate their couplings for speed based
9.4 Low cycle fatigue
on a variety of factors. These include design,
The region of the S--N (stress vs. cycles) curve materials, and manufacturing procedures. Coupling
characterized by high overstress (exceeding the selection considers various operating speed and
yield limit) where life is usually below 103 cycles for application requirements.
steel. It is in the plastic range, and is a function of The rotating speed of the coupling is usually
plastic strain rather than stress. expressed in revolutions per minute (rpm).
9.5 High cycle fatigue 9.10.1 Rated speed
The region of the S--N (stress vs. cycles) curve The maximum speed at which the coupling is
characterized by low overstress (exceeding the capable of transmitting the coupling continuous
fatigue limit) where life is usually above 103 cycles for rated torque while simultaneously subjected to the
steel. rated misalignment and the coupling rated axial
displacement.
9.6 Factor of safety (FS)
9.10.2 Maximum operating speed
The ratio of the appropriate material strength divided
by the calculated stress and is used in the design of The highest speed required by the application.
the coupling. Maximum operating speed shall not exceed the
coupling rated speed.
9.7 Service factors, application factors and
experience factors (SF) 9.10.3 Trip speed

Service factors, application factors or experience The rotational speed of the coupling corresponding
factors (SF) are based on the application and are to the speed at which the independent emergency
applied to the customer specified or normal operat- overspeed device operates to shut down a variable
ing torque. This factor is used in the selection of speed prime mover. Trip speed shall not exceed the
couplings and takes into account the prime mover coupling rated speed.
and the driven equipment. This factor accounts for 9.11 Balance considerations
actual operating conditions or for the unusual
A coupling or coupling component is in balance if all
conditions that occur repetitively.
its weight is centered on its axis of rotation. The
9.8 Allowable temperature unbalance is a measure of how far they are from this
perfect condition. Most standard couplings are
9.8.1 Maximum allowable temperature
supplied without balance correction. High speed
The highest temperature for which the manufacturer and/or special purpose couplings are normally
has designed the coupling. This temperature may provided with balance correction.

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AMERICAN NATIONAL STANDARD ANSI/AGMA 9009--D02

9.11.1 Component balance 9.11.8 Couple unbalance

A procedure for improving coupling balance wherein The condition of unbalance for which the central
the pieces or subassemblies are balanced principal axis of inertia intersects the shaft axis at the
separately before assembly. center of gravity. See figure 7.
NOTE: The quantitative measure of couple unbalance
9.11.2 Assembly balance
can be given by the vector sum of the moments of the
A procedure where an assembled coupling is two dynamic unbalance vectors about a certain refer-
ence point in the plane containing the center of gravity
balanced as a unit.
and the shaft axis.
9.11.3 Potential unbalance If static unbalance in a rotor is corrected in any plane
other than that containing the reference point, the
The maximum amount of unbalance that may exist in couple unbalance will be changed.
a coupling assembly, whether corrected or
uncorrected.
9.11.4 Residual unbalance
The final amount of unbalance that remains in a
coupling component or assembly after balancing Couple
and prior to removal from the balancing machine. unbalance

9.11.5 Inherent unbalance

The unbalance of a homogeneous body caused by Figure 7 -- Couple unbalance
geometric design concentricity tolerances which
results in the displacement of the center of gravity 9.11.9 Dynamic unbalance
relative to the axis of rotation. The condition in which the central principal axis of
inertia is not parallel to and does not intersect with
9.11.6 Assembly check balance
the shaft axis. See figure 8.
A procedure in which an assembled coupling is NOTE: The quantitative measure of dynamic unbal-
placed on a balance machine and the potential ance can be given by two complementary unbalance
unbalance is measured. This can be done to a vectors in two specified planes (perpendicular to the
component balanced coupling, or to an assembly shaft axis) which completely represent the total
unbalance of the rotor.
balanced coupling.
Dynamic unbalance is a combination of static unbal-
9.11.7 Static unbalance ance and couple unbalance resolved into two (and in
some case more than two) transverse planes. Only the
The condition of unbalance for which the central two--plane case is covered in this document. Analytical
principal axis of inertia is displaced only parallel to conversion by vector analysis can be made from dy-
the shaft axis. See figure 6. namic unbalance to static plus couple unbalance and
vice versa. The correction of dynamic unbalance will
NOTE: The quantitative measure of static unbalance achieve complete unbalance correction.
can be given by the resultant of the two dynamic
unbalance vectors.

Static unbalance
Dynamic
Principal axis unbalance
of inertia

(Unbalance weights not diametrically opposed)

Figure 8 -- Dynamic unbalance

Journal axis 9.11.10 Rss (root sum of squares)

Center of The square root of the sum of the squares. This term
gravity
is used in the calculation of potential unbalance. See
Figure 6 -- Static unbalance ANSI/AGMA 9000--C90.

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ANSI/AGMA 9009--D02 AMERICAN NATIONAL STANDARD

9.11.11 Unbalance expression terms (of work) per minute, or 746 Newton meters (of work)
per second.
Unbalance is expressed in terms of principal inertia
axis displacement or the amount of unbalance. 10.2.2 Kilowatts

9.11.11.1 Principal inertia axis displacement The unit of power that has been adopted for
engineering work in the metric system. One kW is
The displacement, measured in mils, microinches equal to 60 000 Newton meters (of work) per minute,
(min), microns or micrometers (mm), of the principal or 1000 Newton meters per second, 44 254 foot
inertia axis with respect to the axis of rotation at the pounds (of work) per minute, or 738 foot pounds (of
balancing plane. work) per second.
9.11.11.2 Amount of unbalance 10.3 Natural frequency
The product of the unbalance mass and the distance The natural frequency of a system is that frequency
of its center of gravity from the axis of rotation. It is where any change in frequency results in a reduction
normally measured in ounce--inches (oz in), gram-- in the displacement.
inches (g in) or gram--millimeters (g mm).
10.4 Resonance
9.12 Balance correction methods
A system vibration, at a frequency, where the
9.12.1 Single plane amplitude, velocity and acceleration are at maxi-
mum. It occurs when a periodic driving force is at a
Method for correcting static unbalance.
driving frequency which equals the natural
9.12.2 Two plane undamped frequency of the system.
Method for correcting couple or dynamic unbalance. 10.5 Critical speed (of a rotating mechanical
system)
The speed at which the excitation frequency
10 System terms matches one of the natural frequencies of the
rotating component(s).
10.1 Torque 10.6 Lateral critical speed
The moment resulting from a force acting in a plane A critical speed where the coupling vibrates
perpendicular to an axis. Torque is obtained by perpendicular to the axis of rotation.
multiplying the force by the perpendicular distance
from the axis to the line of action to the force. Torque 10.7 Torsional natural frequency
is commonly expressed in Newton meters, pound The frequency where the kinetic energy of the
feet or pound inches. rotating mass inertia is equal to the potential energy
T=F×r (3) of the connecting shaft and couplings acting as
torsional springs.
where
10.7.1 Torsional critical speed
T is torque, Nm (lb--in);
The speed at which the torsional excitation frequen-
F is force, N (lb);
cy matches the torsional natural frequency of the
r is distance, m (in). rotating components. Torsional critical speed is a
10.2 Power critical speed of a whole system rather than a
coupling alone.
Power is work per unit time usually expressed as
10.8 Torsional vibration
kilowatts or horsepower.
The periodic angular oscillation in a rotational
10.2.1 Horsepower
system. Causes of torsional vibration are typically
The unit of power that has been adopted for gas pressure in internal combustion engines creat-
engineering work in the English system. One HP is ing peak torques, blade passing frequencies found in
equal to 33 000 foot pounds (of work) per minute, or pumps and fans, inertial unbalance or irregular
550 foot pounds per second, 44 746 Newton meters torque requirements of rotating equipment.

12
AMERICAN NATIONAL STANDARD ANSI/AGMA 9009--D02

10.9 Order number an out--of--squareness equal to the reading or an

eccentricity equal to half the reading.
Order number is the number of exciting pulses per
revolution of a shaft. As an example, a 4--cycle 11.2 Micron
engine delivers one power pulse for every 2 revolu- A micron is a micrometer (mm) = 1 ¢ 10 --6 meters or
tions of the crankshaft for each cylinder. For a 1 ¢ 10 --3 millimeters.
4--cycle and 4--cylinder engine, there will be 2 pulses
for every revolution, and this is an order number of 2. 11.3 Mils
There are other order numbers in that engine. One mil is equal to 0.001 inches.
10.10 Torsional tuning 11.4 Microinch
Torsional tuning refers to the shifting of one or more One microinch equals 1 ¢ 10 --6 inches.
torsional natural frequencies of a coupled system to
11.5 Surface finish
avoid system resonance at a known excitation
frequency. Torsional tuning is normally accom- Two of the more common methods of measuring
plished by varying the torsional stiffness of the surface finish are Ra and Rq (rms) as described
coupling. below.
11.5.1 Ra (arithmetic average)
Ra is the arithmetic mean of the absolute ordinate
11 General terms values within a sampling length, expressed in
micrometers or microinches.
11.1 Total indicator reading (TIR) 11.5.2 rms (root--mean--square), Rq
Total indicator reading is the difference between the Rq is the root--mean--square value of the ordinate
maximum and minimum readings of a dial indicator, values within a sampling length. While rms is still in
or similar device, monitoring a face or cylindrical frequent use, Ra has been preferred since 1950.
surface during one complete revolution of the Roughness measurements in rms may be higher on
monitored surface. With truly flat or truly circular a given surface than those measured by arithmetic
surfaces, the indicator reading implies respectively average, Ra.

13
ANSI/AGMA 9009--D02 AMERICAN NATIONAL STANDARD

(This page is intentionally blank)

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AMERICAN NATIONAL STANDARD ANSI/AGMA 9009--D02

Index Coupling components, 4.15, pg. 4

Coupling definitions, Clause 4, pg. 2
Coupling designs, 4.13, pg. 3
A Coupling flywheel effect, WR2, 8.3, pg. 6
Coupling half weight, 8.12, pg. 8
Adapter plate, 4.15.6, pg. 5
Coupling installation alignment recommendation,
AGMA standard bore, 5.1.8, pg. 5 9.2.4, pg. 9
Aligned shafts, 7.1, pg. 6 Coupling lateral natural frequency, 8.15, pg. 8
Allowable temperature, 9.8, pg. 10 Coupling physical properties and other
Amount of unbalance, 9.11.11.2, pg. 12 characteristics, Clause 8, pg. 6
Angular misalignment, 7.2.2, pg. 6 Coupling rated no load misalignment (static
misalignment), 9.2.2, pg. 9
Angular stiffness (bending stiffness), 8.8, pg. 8
Coupling rating, 9.1.1, pg. 8
Anti--sludge design, 4.8.1, pg. 3
Coupling reaction force, 8.11, pg. 8
Applicability, 1.1, pg. 1
Critical speed (of a rotating mechanical system),
Assembly balance, 9.11.2, pg. 11 10.5, pg. 12
Assembly check balance, 9.11.6, pg. 11 Crown diameter, 4.9, pg. 3
Axial displacement (end float), 7.3.2, pg. 6 Cyclic torque, 9.3.1.2, pg. 9
Axial natural frequency, 8.14, pg. 8
Axial relationships, 7.3, pg. 6
D
Axial stiffness, 8.9, pg. 8
Damping, 8.7, pg. 8
Damping coefficient, ψ, 8.7.2, pg. 8
B Damping ratio (factor of critical damping), 8.7.1,
pg. 8
Backlash, 4.6, pg. 3
Diametral clearance (tip or root clearance), 4.10,
Balance considerations, 9.11, pg. 10 pg. 3
Balance correction methods, 9.12, pg. 12 Diaphragm coupling, 4.14.4, pg. 4
Batch--lube coupling, 4.7, pg. 3 Disc coupling, 4.14.5, pg. 4
Beam coupling, 4.14.15, pg. 4 Distance between shaft ends (DBSE, BSE, BE),
Bellows coupling, 4.14.14, pg. 4 7.3.1, pg. 6

Body bound bolts (body fitted), 4.15.8.1, pg. 5 Double acting (double engagement), 4.4, pg. 3
Dynamic unbalance, 9.11.9, pg. 11
Bores in hubs, Clause 5, pg. 5

C E
Elastomeric flexible element, 4.2.1.3, pg. 2
Chain coupling, 4.14.1, pg. 3
Electrically insulated coupling, 4.11, pg. 3
Clearance fit, 5.2.1, pg. 5
Exceptions, 1.2, pg. 1
Component balance, 9.11.1, pg. 11
Composite coupling, 4.14.16, pg. 4
Compression elastomeric coupling, 4.14.2, pg. 3 F
Constant torque, 9.3.1.1, pg. 9 Factor of safety (FS), 9.6, pg. 10
Continuous torque rating, 9.1.2, pg. 9 Flexible coupling, 4.2, pg. 2
Continuous--lube coupling, 4.8, pg. 3 Flexible element, 4.15.5, pg. 5, 4.2.1, pg. 2
Couple unbalance, 9.11.8, pg. 11 Flexible hub, 4.15.1.3, pg. 4

15
ANSI/AGMA 9009--D02 AMERICAN NATIONAL STANDARD

Floating shaft center assembly, 4.15.4, pg. 4

M
Floating shaft coupling, 4.14.9, pg. 4
Mandrel bore, 5.1.7, pg. 5
Flooded mesh (dammed) coupling, 4.8.2, pg. 3
Marine style coupling, 4.14.7, pg. 4
Marine style gear coupling, 4.14.7.1, pg. 4
G Mass, M, 8.1, pg. 6
Maximum allowable temperature, 9.8.1, pg. 10
Gap, 4.16, pg. 5
Maximum bore, 5.1.2, pg. 5
Gear coupling, 4.14.6, pg. 4
Maximum continuous misalignment, 9.2.1, pg. 9
Gear hub (flex hub), 4.15.1.1, pg. 4
Maximum operating speed, 9.10.2, pg. 10
General terms, Clause 11, pg. 13 Mechanical element, 4.2.1.1, pg. 2
Grid coupling, 4.14.10, pg. 4 Metallic element, 4.2.1.2, pg. 2
Microinch, 11.4, pg. 13

H Micron, 11.2, pg. 13

Mils, 11.3, pg. 13
Half coupling, 4.5, pg. 3 Minimum allowable temperature, 9.8.2, pg. 10
Half coupling effective center of gravity, 8.13, pg.8 Misaligned shafts, 7.2, pg. 6
Hardware, 4.15.8, pg. 5 Misalignment terms, 9.2, pg. 9
High cycle fatigue, 9.5, pg. 10 Modified standard couplings, 4.13.2, pg. 3
Horsepower, 10.2.1, pg. 12 Moment simulator, 4.15.7, pg. 5
Hub, 4.15.1, pg. 4 Momentary torque limit, 9.1.4, pg. 9
Hub bore, 5.1, pg. 5
Hub--to--shaft fits, 5.2, pg. 5 N
Natural frequency, 10.3, pg. 12
I Nominal bore, 5.1.1, pg. 5
Non--standard bore, 5.1.9, pg. 5
Inherent unbalance, 9.11.5, pg. 11
Non--standard keyways, 6.5, pg. 6
Interference fit, 5.2.2, pg. 6
Normal (steady state) operating torque, 9.3.1,
pg. 9
Normative references, Clause 2, pg. 1
K
Key, 6.1, pg. 6
O
Keys, keyways and keyseats, Clause 6, pg. 6
Operating terms, 9.3, pg. 9
Keyseat, 6.3, pg. 6
Order number, 10.9, pg. 13
Keyway, 6.2, pg. 6
Others, 4.2.1.4, pg. 2
Kilowatts, 10.2.2, pg. 12

P
L Parallel offset misalignment, 7.2.1, pg. 6
Lateral critical speed, 10.6, pg. 12 Peak torque rating, 9.1.3, pg. 9
Limited--end--float coupling, 4.12, pg. 3 Pilots (rabbets/spigots/registers), 4.15.9, pg. 5
Low cycle fatigue, 9.4, pg. 10 Pin and bushing coupling, 4.14.11, pg. 4

16
AMERICAN NATIONAL STANDARD ANSI/AGMA 9009--D02

Polar mass moment of inertia, J, 8.4, pg. 6 Speed considerations, 9.10, pg. 10
Potential unbalance, 9.11.3, pg. 11 Spline bore, 5.1.10, pg. 5
Power, 10.2, pg. 12 Spring coupling, 4.14.13, pg. 4
Principal inertia axis displacement, 9.11.11.1, Standard couplings, 4.13.1, pg. 3
pg. 12 Standard keyways, 6.4, pg. 6
Pulsating (one--way) torque, 9.3.1.2.1, pg. 9 Static unbalance, 9.11.7, pg. 11
Straight (finished) bore, 5.1.4, pg. 5
R Surface finish, 11.5, pg. 13
Symbols, Clause 3, pg. 1, Table 1, pg. 1
Ra (arithmetic average), 11.5.1, pg. 13
System terms, Clause 10, pg. 12
Radial stiffness, 8.10, pg. 8
Rated speed, 9.10.1, pg. 10
Reduced moment coupling, 4.14.8, pg. 4 T
Residual unbalance, 9.11.4, pg. 11 Tapered bore, 5.1.5, pg. 5
Resonance, 10.4, pg. 12 Terms used in coupling selection, Clause 9, pg. 8
Reversing (alternating) torque, 9.3.1.2.2, pg. 9 Torque, 10.1, pg. 12
Rigid coupling, 4.1, pg. 2 Torque amplification factor (TAF), 9.3.2.1, pg. 10
Rigid hub , 4.15.1.2, pg. 4 Torque rating terms, 9.1, pg. 8
rms (root--mean--square), 11.5.2, pg. 13 Torsional critical speed, 10.7.1, pg. 12
Rough bore, 5.1.6, pg. 5 Torsional natural frequency, 10.7, pg. 12
Rss (root sum of square), 9.11.10, pg. 11 Torsional stiffness, k, 8.5, pg. 7
Torsional tuning, 10.10, pg. 13

S Torsional vibration, 10.8, pg. 12

Total indicator reading (TIR), 11.1, pg. 13
Scope, Clause 1, pg. 1
Transient misalignment limit, 9.2.3, pg. 9
Service factors, application factors and experience
factors (SF), 9.7, pg. 10 Transient torque, 9.3.2, pg. 10

Shaft penetration factor, 8.6, pg. 8 Transitional fit, 5.2.3, pg. 6

Transmitted axial force, 9.9, pg. 10
Shaft relationships, Clause 7, pg. 6, Fig 1, pg. 7
Trip speed, 9.10.3, pg. 10
Shear elastomeric coupling, 4.14.3, pg. 3
Two plane, 9.12.2, pg. 12
Short circuit torque, 9.3.2.2, pg. 10
Types of flexible couplings, 4.14, pg. 3
Single acting (single engagement), 4.3, pg. 2
Single plane, 9.12.1, pg. 12
Sleeve, 4.15.2, pg. 4 U
Sliding block, 4.14.12, pg. 4
Unbalance expression terms, 9.11.11, pg. 12
Solid hub, 5.1.3, pg. 5
Spacer, 4.15.3, pg. 4
Spacer length, 4.15.3.1, pg. 4 W
Special couplings, 4.13.3, pg. 3 Weight, W, 8.2, pg. 6

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