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Engineering

Assignment

Disc and Leaver Braking System

Report

By Eric Cheung

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Abstract

In todays society everything is about speed. But with speed comes danger. Therefore the need for

stronger more effective braking systems. Most reliant force used for braking is friction force. Each

material has different properties and effectiveness in terms of frictional force. There are many different

types of braking systems, made from many different materials. Design and material both affect the

effectiveness of the brakes. Within the report I will analysis the materials used in my disc brake, how

disc brakes work and what improvements I can make to better my breaking system.

Introduction

With the invention of the wheel believe to originate at the beginning of mankind so did the brake.

Where there are wheels to move their must be breaks to stop. A brake is a mechanical device made to

slow down / stop a rolling wheel. Through friction the kinetic energy from the wheel is transformed into

heat energy to slow it down. Besides heat many brakes convert kinetic energy to sound or light (when

force really hard and sparks appear from the wear and tear of the brake).

There are many different types of brakes:

y Frictional brakes

y Pumping brakes

y Electromagnetic brakes

My braking system is a frictional brake. Firstly what is friction? Friction is the force which resists the

relative motion of 2 or more solid surfaces or in other words materials sliding against each other.

Frictional brakes work with a moving object for this example a car. Car moves because of its wheels

being pushed forward b the friction between the wheel and the road. The coefficient of friction with

gravel and rubber is pretty high so if the wheel is stopped the frictional power between the wheel and

the ground would stop the car. But how to stop the wheel? Brakes, wheels have disc brakes 2 metal

pads on each side of a disc which is connected to the wheel. When you press on your foot brake it

creates a chain reaction to all the disc brakes at the wheels, it creates a force which pushes the metal

pads against the disc. Through friction kinetic energy from the wheel is created into heat energy and

sound energy which slows it down.This one only one form of many different types of friction breaking

systems.

In my analysis I will give you an understanding of how my braking system works (explain the design, how

friction slows it down).

I will go through investigations and analysis of 2 materials foam and sand paper, as well as their

engineering properties when placed under friction force. And make a table of results from my finding ofhow effective each material is. Also ill draw an orthogonal and isometric drawing of the braking system.

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Analysis

The design of my break incorporates the ideas of both a disc break as well as a leaver brake. Along with

the idea of incorporating 2 types of breaking systems into one, I tried to maximize the amount of surface

area. By increasing the amount of surface area, it increases the amount of friction affected space. If

there is more surface area the force is spread out and less concentrated. Concentrated force usuallyenhances the effects of materials getting eroded away.

The swinging pieces of wood that are kind of like flaps on either side of the wheel are the pad of the disc

brake. With a string attached to one end of each pad and a focus point in between them when the string

is threaded through the whole of the focus point and a force is applied the two pads move towards the

wheel and squeeze together. This causes friction with the face of the wheel and the pad. The leaver

which is lying on top of the wheel when a force is applied onto it, it creates friction with the leaver and

then wheels rim. And with the increase of force applied the frictional force will increase therefore when

the force is stronger than the kinetic energy spinning the wheel it would gradually slow it down to a stop.

The bigger the difference between the frictional force and the kinetic force the fast it would stop.

Materials surface Durability Effectiveness (out of

10)

Foam Smooth, spongy Quite easily worn away 9

Sand paper Coarse, rough hard More durable but wears away the wheel. 4

Result Summery

Results from wheel testing sandpaper

Weight(g)/speed

settings

2 4 6 8 10 12 14 16

100g Yes No No No No No No No

200g Yes Yes Yes No No No No No

500g Yes Yes Yes Yes Yes Yes No No

Results from wheel testing foam

Weight(g)/speed

settings

2 4 6 8 10 12 14 16

100g Yes Yes Yes Yes Yes Yes Yes No

200g Yes Yes Yes Yes Yes Yes Yes Yes

500g Yes Yes Yes Yes Yes Yes Yes Yes

Conclusion

In conclusion, the results show that the frictional force with the material foam is better than sand paper.

But both of these materials could not be used in our high speed vehicles since its eroding qualities are

too effective and the constant replacement and cost of replacements would not be beneficial.

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AcknowledgementsArif Sudarsono : partner in manufacturing and report

Bibliography

http://en.wikipedia.org/wiki/Brake

http://www.westfields-

h.schools.nsw.edu.au/sites/swsRepo/8384/asset/2011/6/19eb9ef93066df58013096905154495d.pdf

www.tuftl.tufts.edu/files/asutphen/Friction_Testing.2.doc

http://www.engineeringtoolbox.com/friction-coefficients-d_778.html

http://en.wikipedia.org/wiki/Friction

http://4.bp.blogspot.com/_zh8BM1LvnzA/TAXS3DIgZJI/AAAAAAAAADI/5x3w2a96dho/s1600/brakes.jpg

Appendices

This is the results of an experiment similar to ours. It involved a wooden door knob and a few other

materials the door knob is clamped by the material and a weight on top. And the about of force need to

turn the doorknob was then measured.

As you can see the coefficient of friction of the yoga mat is pretty strong in comparison to the others.

The material that yoga mat is made of is similar to the foam we used in our experiment. For further

information follow the link www.tuftl.tufts.edu/files/asutphen/Friction_Testing.2.doc

Wooden Door Knob

Load Weight vs. Upper Coefficient of Friction

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

250 300 350 400 450 500 550 600 650

Load Weight (grams)

Co

effofFriction,upper

40 A Urethane

60A Urethane

Tan Rubber

Yoga Mat

Rugby Gloves