Tiarna Marcos 11ENS v2
Tiarna Marcos 11ENS v2
Tiarna Marcos 11ENS v2
https://empirecityautoparts.com/products/parts/drum-brake/
Tiarna Marcos
Preliminary Engineering Studies
UTS WANAGO Program
10 June 2021
1
Table of Contents i
1.0 INTRODUCTION…………………………………………..…………………………...1
1.1 Functionality…………………….……………….…..……………………………..1
1.2 Usage………………………………………………………………………………..5
1.3 Engineering Principles Used………………..……….……………….…..……….6
1.4 Advantages and Disadvantages……….……………….…..……………………..8
1.5 Materials and Manufacturing……….……………….……..……………….…...10
2.0 RESEARCH…………………………..………………………..………………………...16
3.0 PROCEDURE………………..………………………..………………………………...17
4.0 CONCLUSION………………..………………………..……………………………....21
5.0 BIBLIOGRAPHY………………..………………………..……………………………..22
6.0 APPENDICES………………..………………………..………………………………..28
APPENDIX A: Brake Shoe Linings………..………………………..………………....28
APPENDIX B: Greenhouse Gas Emissions………………………………………..…29
1
Introduction 1
Functionality:
Drum brakes are a unique, albeit outdated, design of brakes, with a method of
braking different from other varieties.
The Components
1. The Wheel Hub: Essentially a housing for the entire assembly, the hub is
attached to the brake drum and wheel, keeping out external moisture and dust.
2. The Backplate: Sometimes referred to as a ‘Torque Plate’, this is a stationary
circular sheet that holds all components together and absorbs torque from the
braking action. All components exert pressure on this plate.
3. The Brake Drum: The drum rotates on the wheel and axle of each individual
wheel, acting as the wheel side braking surface to be stopped by the shoes.
4. Brake Shoes: A pair of brake shoes, on either side of the interior backplate
assembly, are held to the backplate by hold-down pins. The curved part of them
is dubbed the ‘web’ while the arc-like component resting on the side of the web
is called the ‘lining table’.
5. The Lining: A relatively thick piece of friction material riveted or glued to the
lining table of the shoes.
6. Upper and Lower Retaining Springs: These two springs, positioned on the upper
and lower halves of the backplate, are fused with the brake shoes, returning
them to their original positions once the brake pedal has been released.
7. The Master Cylinder and Brake Booster: When the brake pedal is pressed, a
certain degree of force is applied. This force is then amplified by the brake
booster/servo system and converted into hydraulic pressure by the master
cylinder, which then feeds the pressure to the wheel cylinder through
hydraulic/brake fluid.
8. The Wheel Cylinder (Image 1): The hydraulic component of the entire setup, the
wheel cylinder receives the hydraulic pressure from the master cylinder and
converts it into mechanical force exerted onto the shoes. Mechanical designs,
such as the two-wheeler & auto-rickshaw, will use a lever-activated cam instead
and pneumatic designs will use compressed air and an s-cam.
a. The Inlet Port: Situated at the back of the wheel cylinder housing, it
allows hydraulic fluid into the cylinder.
b. The Bleeder Valve: Located just above the inlet port, this valve forces air
out of the cylinder for maximum efficiency.
2
c. The Cylinder Body: A simple housing for the components inside; the
return spring and piston cup expanders. The expanders push into the
piston cups, pushing the pistons and dust boots, finally contacting the
shoes.
Types
There are three distinct types of drum brakes, named according to how the
shoes interact with the drum.
1. Leading/Trailing shoe type: The two shoes have different roles which alternate
depending on the direction in which the wheel is rotating. When rotating
anti-clockwise, the left shoe is the leading shoe, and when travelling clockwise
this job is swapped to the right shoe.
a. The Leading/Primary shoe: moves in the direction of rotation when it
contacts the drum and is dragged into the drums friction surface. This
rotation helps this contact occur with greater pressure generating a
stronger braking force. This is known as a self-boosting effect.
b. The Trailing/Secondary shoe: is less effective as it moves against the
direction of rotation.
4
2. Twin Leading shoe type: An uncommon design in which two shoes possess the
same roles in retarding movement, making for ineffective backwards braking,
but improved forwards braking.
a. Two Shoes: In the forward direction both shoes are leading, generating
significant braking force. Yet, when travelling in reverse, both shoes are
trailing, resulting in a poor braking force.
b. Two Wheel Cylinders: These each are responsible for the movement of
one shoe by producing displacement in either the left or right direction.
One cylinder is positioned at the top and the other at the bottom.
3. Duo Servo: Two brake shoes (primary and secondary)
a. Two Shoes: These two brake shoes, primary and secondary, using
servo-action in both directions. The primary shoe generates strong
pressure with the servo-effect, this pressure is then transmitted to the
secondary shoe.
b. An Adjuster: An adjustable floating link connecting the two shoes at the
bottom of the backplate, so that the bottom of the shoes move in the
direction of the drum. A small force passes through this link, allowing for
servo-action, where the primary shoe applies force to the secondary
shoe.
c. The Wheel Cylinder: Positioned at the top, this activates the shoes.
d. Anchor Pin: Also located at the top of the backplate, this component
prevents shoe rotation past it. This causes the rear shoe to be pressed
harder into the drum so that it does most of the braking work, which,
overall, is much greater than the other two types.
Usage:
Drum brakes are characterised by their effectiveness, yet low performance and
cost efficiency. As a result, they are often components of ‘cheap’ cars, where high
performance is not concerned, rear wheels, which require significantly less braking
force, and large machinery without built-in discs.
Such brakes are not used exclusively in transport, they are also used in
conjunction with other, usually disc, brakes. Leading/Trailing shoe types are employed
to the front wheels of scooters and small bikes and Twin Leading shoe types are used
in applications expecting little backward travel; small-mid sized trucks and motorcycles
for example. Duo Servo types are used for commercial purposes requiring excessive
braking force; passenger car parking brakes, truck centre brakes and forklift brakes
amongst others. Akebono is a manufacturing company which supplies Duo Servo
drum brakes to other companies for forklifts.
General machinery, especially those in factories, search for cheap, practical,
low-maintenance systems with long lives. Indicating drum brakes as perfect
candidates, especially in devices without pre-built discs, rotors, or disc assemblies.
They are also particularly beneficial for stopping solid, non-cylindrical, shafts or
rotating objects from the outside, with minor design modifications. Such machinery
may include overhead cranes and trolleys, often using spring-applied, electromagnetic,
or pneumatic designs. Pneumatic variants are popular for such purposes as they
require a pneumatic compressor, which many factory devices already have.
6
Frictional brakes and, more specifically, drum brakes use a variety of principles
and understandings to create efficient and effective braking systems.
Heat Dissipation
Brakes generate notably high levels
of heat, in fact, a speeding car’s brakes can
heat to over 510˚C (Hengshui Kaiyue Brake
Pads Co., 2019). As a result car brakes must
employ several methods of combatants;
using materials with exceptionally high
melting points and heat resistance, as well
as punched out holes and cooling fins. The
holes allow for greater airflow, allowing in
cool air, they also — like cooling fins —
increase the surface area so that heat is
Image 4: Thermal stress of a brake drum.
http://ijiset.com/vol6/v6s6/IJISET_V6_I6_18.pdf.
7
readily transferred outside of the drum. Engineers of drum brakes must understand
the necessity for efficient heat dissipation and how to create it, as the effects of
overheating brakes range from minor thermal expansion to broken brakes. In image 4,
it can be observed that the heat is concentrated on the outer edges, where there are
not many holes. The addition of holes would bring out the heat, as thermal energy
naturally flows from hot to cold, or more specifically, from a high concentration to a
low concentration.
Pascal’s Law
Pascal’s Law is the understanding that when a change in pressure occurs
anywhere in a confined incompressible fluid, the pressure changes by the same
amount on every part of the fluid. The law allows mechanical force to be converted
into pressure which is equally distributed throughout and through the fluid. The
pressure itself is amplified and calculated using the formula: P = F/A. This enables a
small force across a piston of small cross sectional area to be converted to a larger
force, across a piston of larger cross sectional area. However, in line with the Law of
Conservation of Energy, the displacement of the larger piston will be proportionally
lower. In practice, a brake pedal, when depressed, may travel in the order of 100mm,
however, the brake shoes travel in the order of 1mm.
Each model or type of brake comes with its own positive and negative qualities,
those listed below are for an average drum brake.
Advantages
Drum brakes have:
- A greater braking force than an equal diameter disc brake.
- A lower cost of manufacturing, making them cheap and cost-efficient.
- A lower frequency of maintenance than disc brakes due to their
increased corrosion resistance and self-adjustment features.
- Less generated heat in many applications, as they are often used for
machinery or rear vehicle wheels.
- Less required input force due to their built-in self-energising feature,
which multiplies input force (hydraulic pressure).
- Wheel cylinders which are easier to recondition than disc brake callipers.
- Brake shoes are able to be reused following remanufacturing.
- The ability, depending on the type of drum brake, to generate an equal
braking force in either clockwise or anti-clockwise directions.
Drum brakes also take up less space and don’t apply an overhung load to the
shaft in industrial settings.
Disadvantages
Drum brakes:
- Are less heat efficient than disc brakes, as the surface area of any given
brake drum is significantly smaller than that of a brake disc.
- Limited in their potential methods for heat dissipation, when compared
to disc brakes.
- Cannot be used for heavy braking applications as the excessive heat
would be too great, leading to brake fade, drum distortion and vibration
or noise pollution.
- Often have an inconsistent braking feel due to thermal expansion of the
brake drums interior diameter.
- Shoes may become glazed due to overheating.
- May overheat to the point of brake fluid vaporization, in extreme cases.
- Experience brake fade, that is, reduced braking power, faster. Their
self-adjustment features attempt to resolve this but in some cases, they
may cause brake grab.
9
In industrial applications, drum brakes are quite limited as they cannot handle
high shaft speeds, unlike disc brakes capable of operating with high shaft speeds.
10
Components Manufacturing
https://www.caravansplus.com.au/bra
ke-hub-drum-landcruiser-6-stud-suit-2
11
50mm-alko-electric-slimline-bearings-p
-270.html.
https://www.roughtrax4x4.com/genuin
e-l-h-rear-brake-backing-plate.html.
Material Properties
Cast iron is slow to wear and available in many types, all made by smelting
iron-carbon alloys with a minimum of 2% carbon content. When concerning brakes,
the most notable type is gray cast iron, which has the following properties:
- A tensile strength of 100-350 MPa.
- A compressive strength 3-4 times greater than its tensile strength.
- A hardness around 200HB.
- Low toughness and plasticity.
13
Copper has several advantages useful within brake linings; an exceptionally high
melting point, it’s malleable, ductile and very good at conducting heat and electricity.
Although the material is used sparingly as too much metal in linings can prove
damaging or contribute to wear. Copper is also associated with significant health risks.
Long term concentrated exposure, gained from working with the substance or living
near a forge can cause irritation of the nose, mouth and eyes, headaches,
stomachaches, dizziness, vomiting and diarrhea. In extreme cases, these symptoms
extend to liver and kidney damage or even fatal conditions. It also, when in soil, limits
biodiversity and causes fatal diseases for animals, primarily copper poisoning in
sheep. An overuse of copper would prove to be a severe risk to the health of both
humanity and the environment.
Anodized coatings, on housings and pistons, are excellent ways to increase the
lifespan of said parts. Anodizing is an electrolytic treatment of metallic surfaces that
increases the thickness of the natural oxide layer by around 30µm/hr, providing the
following properties:
- Resistance to extreme temperatures, weather, dirt and corrosive
materials.
- Durability.
- A tough, corrosion and wear-resistant surface.
Friction linings are potentially the most important component of the system,
without them the motion would never stop and all other parts would be pointless.
They require specific standards to be met, such as a high coefficient of dynamic
friction, ideally around 0.35 to 0.42 with an equal coefficient of static friction. They
must also be heat and wear resistant (see Appendix A for more), as they are
consistently exposed to extreme levels of either. To achieve such traits, friction linings
are compound materials made of 20+ raw materials; friction modifiers (e.g graphite
and cashew nut shells), powdered metals that resist heat fade (e.g lead, zinc, brass,
aluminium), binders, curing agents and fillers to reduce noise (e.g rubber chips).
Characterised by the amount of these materials, friction linings are split into several
different types.
15
1. Non-asbestos organic:
a. Organic fibres, e.g those found on coconut shells, are bonded by
pressure then held by adhesives.
b. These are environmentally friendly and quiet, although they do generate
dust and are somewhat ineffective.
c. Rubber, glass, resins and even Kevlar are used.
2. Semi-metallic:
a. These are composed of up to 65% metal — typically brass, copper and
steel — allowing for an abrasive, harder lining with greater durability and
greater stopping power. They offer greater heat dissipation at a lower
price, while producing less dust making maintenance easier.
b. Although the metal's own abrasiveness develops heat, reducing the
brakes lifespan and creating excessive, unnecessary noise.
3. Ceramic:
a. These use copper and another material that is both good for heat
dissipation and soft, to limit metal-to-metal wear and consequent noise
pollution.
b. These are lightweight alternatives that less dust and attempt to limit
noise at no cost to the systems effectiveness. As a result they are very
expensive and not used in everyday vehicles.
● Low-steel linings are made of 10-20% steel.
● Non-steel linings are made of pulps, metallic fibers, and/or ceramic fibers.
● Metallic linings are made from sintered alloy, involving metallic particles fused
with heat and pressure to create a high friction resistance
● Inorganic linings are usually C/C composites, made of carbon fibre for the sake
of thermal stability and light weights.
One popular material is a non-asbestos organic material called Phenol resin. This resin
has:
- Improved thermal resistance.
- A high friction coefficient at different loads and speeds.
- High-temperature stability (up to 300–350°C).
- High chemical stability.
- Excellent fire retardance.
- Low smoke and toxicity emissions.
- Good friction properties.
- And, unfortunately, poor wear resistance.
The resin is often given other fillings to boost its desired qualities and aid with its poor
properties; wood flour, cellulose, minerals, silica, carbon and glass fibers, talc, fabric
fibers, synthetic fibers, paper, and aramid fibers.
16
Research 16
Engineers are trusted with the development and innovations of society, with
this trust, comes an innate responsibility to put their target demographics first. In
regards to drum brakes, pollution and its ability to tolerate minor failures need to be
considered. For the sake of people, animals and the environment, new systems must
be eco-friendly and produce little to no pollution. These qualities must be met during
and post-production, passing on a degree of this responsibility to manufacturers. In
2019, 23% of the total USA greenhouse gas emissions were caused by industrial
sectors and manufacturers, which included approximately 2,000 Million Metric Tons
(The United States Environmental Protection Agency, 2021). This high level of air
pollution is a drastic danger to an individual’s health, safety and livelihood, potentially
causing respiratory issues much like the carcinogenic asbestos did. Noise pollution is
also an important factor as it makes communication difficult and masks sounds of
oncoming traffic or warning alarms. Section 136 of the 1997 NSW POEO (Protection of
the Environmental Operations) Act aims to solve such issues by making distribution of
products that emit more than regulated levels of noise, particularly in motor vehicles.
The Act overall limits circumstances such as not being able to hear any indications of
breakage or part failure. Part failure, particularly in brakes, can prove fatal, hence the
goal of installing a tolerance for minor failures and elimination of a single point of
failure. Ideally, safe brakes should be able to withstand such errors until proper
maintenance or repairs can be conducted, and the loosening of a small screw should
not be a life or death element.
Procedure 17
Sketches:
Note that all scales are to the CAD model not a physical model. The CAD model is
already scaled down and the sketches use the fusion360 dimensions and base
measurements.
Model:
This model is a simple twin leading shoe type drum brake, without any self-adjustment
or handbrake mechanisms. The drums cooling fins are inspired by the following
image.
Source: https://forums.jag-lovers.com/t/odd-disc-brakes-on-xk120-chassis/382522/9.
3D views:
20
Front:
Wheel Cylinder:
Download: https://a360.co/3pBEmng.
21
Conclusion 21
My drum brake model, featured above (pages 19-20), holds all essential
components of a standard drum brake; a backplate, drum, retaining springs, wheel
cylinder and two shoes fitting with friction lining. The backplate is a simple solid plate
of aluminium, as it conducts heat better than cast iron, with three holes. The largest
hole allows space for the handbrake cable and the small two are for the wheel
cylinders inlet port and bleeder valve. The drum is made of grey cast iron with several
holes, which increase airflow and a ring of cooling fins, increasing the exterior surface
area to ultimately speed up heat transfer. These two features enable efficient heat
dissipation and improved performance. The retaining springs are made of stainless
steel, the shoes of steel and anodized aluminium and the linings of phenolic resin.
Bolts and other small components use stainless steel to limit rust and consequent
machine failure.
Overall the brake is simple and effective at its designed purpose, but lacking in
certain areas. One such area is the self-adjustment system, without this the brakes life
is severely reduced and dangerous situations may arise in the event of intolerable
friction wear. My model is also without a handbrake cable or any emergency braking
systems. Alternative systems may use material better considering the total weight of
the assembly.
22
Bibliography 22
Akebono-brake.com. (2021). Drum Brakes|Brakes for Automobiles|Product|
Products and Technologies | Akebono Brake Industry Co., Ltd. [online] Available at:
https://www.akebono-brake.com/english/product_technology/product/automotive/dru
m/. [Accessed 27 May 2021].
Allen, D.J. and Ishida, H. (2001). Thermosets: Phenolics, Novolacs, and
Benzoxazine. Encyclopedia of Materials: Science and Technology, pp.9226–9229.
[Accessed 7 Jun. 2021].
Analysis Inc. (2021). Air Brake Basics Part 6 - Analysis Inc. [online] Available at:
https://www.analysis-inc.com/reference/air-brake-basics/air-brake-basics-part-6/.
[Accessed 7 Jun. 2021].
Cai Peng, Yanming Wang, Tingmei Wang and Qihua Wang (2015). Effect of resins
on thermal, mechanical and tribological properties of friction materials. [online]
ResearchGate. Available at:
https://www.researchgate.net/publication/272891640_Effect_of_resins_on_thermal_me
chanical_and_tribological_properties_of_friction_materials. [Accessed 7 Jun. 2021].
Delphi Aftermarket. (2021). Master, Slave and Wheel Cylinders | Delphi Auto
Parts. [online] Available at:
https://www.delphiautoparts.com/gbr/en/product/master-slave-and-wheel-cylinders.
[Accessed 27 May 2021].
Grabcad.com. (2021). Free CAD Designs, Files & 3D Models | The GrabCAD
Community Library. [online] Available at:
https://grabcad.com/library/wheel-cylinder-2. [Accessed 6 Jun. 2021].
Hemmings. (2013). Tech 101 - How to choose the right brake friction material.
[online] Available at:
https://www.hemmings.com/stories/2013/08/30/tech-101-how-to-choose-the-right-bra
ke-friction-material. [Accessed 7 Jun. 2021].
Hindon. (2021). Industrial Drum Brakes | Fail Safe Drum Brakes | Hindon.
[online] Available at: https://www.hindon.com/products/industrial-brakes/drum/.
[Accessed 5 Jun. 2021].
McHone Industries, Inc (2020). A Guide to Carbon Steel Grades (Plus a Chart).
[online] Mchoneind.com. Available at:
https://blog.mchoneind.com/blog/carbon-steel-grades-chart. [Accessed 7 Jun. 2021].
New South Wales Environment Protection Authority (2013). Noise Guide for
Local Government. [online] Noise Guide for Local Government. Available at:
https://www.epa.nsw.gov.au/-/media/epa/corporate-site/resources/noise/20130127ng
lg.pdf. [Accessed 9 Jun. 2021].
Opgi.com. (2021). Brake Drum, Rear, 1964-72 CH/EC/MC, 9-1/2" X 2", 3" Tall,
Finned Type. [online] Available at:
https://www.opgi.com/brake-systems/drum-brakes/brake-drums1/brake-drum-rear-19
64-72-checmc-9-12-x-2-3-tall-finned-type-bd60094.html. [Accessed 7 Jun. 2021].
Ouarhim, W., Zari, N., Bouhfid, R. and Qaiss, A. el kacem (2019). Mechanical
performance of natural fibers–based thermosetting composites. Mechanical and
Physical Testing of Biocomposites, Fibre-Reinforced Composites and Hybrid
Composites, [online] pp.43–60. Available at:
https://www.sciencedirect.com/science/article/pii/B9780081022924000035. [Accessed
7 Jun. 2021].
Ques10.com. (2021). Short notes on: Leading and Trailing Shoe. [online]
Available at:
25
https://www.ques10.com/p/20780/short-notes-on-leading-and-trailing-shoe/.
[Accessed 27 May 2021].
Quora.com. (2021). Why do my brakes have holes, is it better for making my car
stop or what is the point? - Quora. [online] Available at:
https://www.quora.com/Why-do-my-brakes-have-holes-is-it-better-for-making-my-car-
stop-or-what-is-the-point. [Accessed 6 Jun. 2021].
Sales and Support (2018a). How Brakes Work, Types of Industrial Brakes, &
Getting the Most From Them. [online] kor-pak.com. Available at:
https://kor-pak.com/brakes-work-types-industrial-brakes-exist-get-life/. [Accessed 9
Jun. 2021].
Sales and Support (2018b). The Best Brake Lining Materials | Brake Liners |
Brake Linings. [online] kor-pak.com. Available at:
https://kor-pak.com/best-brake-lining-materials/. [Accessed 7 Jun. 2021].
Sales and Support (2018c). What Are the Best Friction Materials for Brake
Lining? [online] kor-pak.com. Available at:
https://kor-pak.com/best-friction-materials-brake-lining/. [Accessed 7 Jun. 2021].
The Pros and Cons of cars with drum brakes (2017). The Pros and Cons of cars
with drum brakes. [online] Haynes Publishing. Available at:
https://haynes.com/en-gb/tips-tutorials/pros-and-cons-cars-drum-brakes. [Accessed
31 May 2021].
Vehicle Service Pros. (2019). The physics of braking. [online] Available at:
https://www.vehicleservicepros.com/service-repair/the-garage/article/21176879/the-p
hysics-of-braking. [Accessed 31 May 2021].
Visit profile (2020). How Drum Brake Works? It’s Advantages & Disadvantages.
[online] Blogspot.com. Available at:
https://cat-engines.blogspot.com/2020/03/how-drum-brake-works-its-advantages.html
. [Accessed 31 May 2021].
www.youtube.com. (2019). How do drum brakes work in cars and light vehicles.
(3D animation). [online] Available at:
https://www.youtube.com/watch?v=ApuBEn2zct8&ab_channel=SimonRaisbeck.
[Accessed 27 May 2021].
27
Appendix 28
The friction coefficient at wear rate of friction linings tested on various frictional resins. Source:
https://www.researchgate.net/publication/272891640_Effect_of_resins_on_thermal_mechanical_and_tribological_properties_of_fric
tion_materials.
29
Source: https://www.epa.gov/ghgemissions/sources-greenhouse-gas-emissions.
30