Engineering Report - Braking SystemsSean Okunbor sent himself a copy of this report - possible plagiarism.

Abstract:

This report will provide a detailed outline of the significant developments involved in the invention and improvement of braking systems, while also thoroughly analysing and evaluating the wide variety of materials used in within braking systems. It will conclude with a detailed discussion of how the many technological advances have influenced both braking systems and the people who rely on them.

Significant Developments:

The invention of the braking system can be traced back thousands of years, since then numerous significant developments have drastically improved the usability, effectiveness and durability of the braking system. Without these advances, many modern forms of transport - for example cars and trains - would be physically impossible.

These significant developments include:

● Pre 1800’s - External Shoe Brake: With the early development of horse drawn carts and carriages and then further development into steam powered vehicle, a means to slow down or remain stationary was required. The External shoe brake is the simplest form of a brake, consisting of a curved block of wood actuated on a lever system. When braking was required the driver or passenger would apply a force to the lever, causing the shoe to make contact with the wheel. This form of brake only worked on wheels that were produced from steel or had a steel rim - they were ineffective in conjunction with a rubber tyre.

● Late 1890’s - Contracting Band Brake: In the late nineteenth century, due to the ineffectiveness of External Shoe Brake on rubber tyres, the Contracting band brake was implemented. It involved the driver apply a force onto a lever which pulled a metal band, the band then contracted onto a hub situated on the same axle as the wheel. Later versions of the Contracting band brake included materials with a higher friction. When water or dirt entered the braking system, the friction between band and hub was drastically decreased - leading to an ineffectiveness in wet or dirty conditions.

● 1902 - Mechanical Drum Brake: The first Mechanically operated drum brake was

used in 1902 by the motor vehicle manufacturer Louis Renault, the concept of the drum brake is still being implemented in modern applications. When a linkage is pulled, usually via a lever, the shoes (housed internally) are forced against the outside drum of the brake - which is attached to the wheel. This generates a friction and slows the wheels rotative speed. The Mechanical drum brake had a number of drawbacks, including the loss of friction caused by the linkages between shoes and large amounts of wearing of moving parts (lead to regular servicing). However this form of brake was the first to overcome pollution issues caused by water and dirt as a result of its enclosed nature.

● 1918 - Hydraulics: In 1918 Malcolm Loughead came up with the idea of a four wheel hydraulic braking system. Through the use of fluids, a force applied to a brake pedal could be evenly distributed to all wheels of a vehicle. The brake pedal is placed within a close proximity to the driver who can actuate it with their foot. Through a variation in size of cylinder, the force applied by the driver can be magnified, increasing the force applied to brakes and decreasing stopping distance.

● 1902 (Initial patent) to the 1950’s (Popularity) - Disc Brake: With the increasing speed capabilities and weight of motor vehicles, a more effective means to reduce speed was needed. The Disc brake was originally designed and patented in 1902 by William Lanchester, however it did not become widely used until the mid twentieth century. This braking system commonly combined hydraulics to reduce the force that the driver is required to apply. It involves a ‘C’ shaped calliper and a rotor attached to the wheel hub, when a force is applied to the brake pedal the piston pushes the two brake pads onto the calliper and slows the vehicle down.

● 1962 - Electromagnetic Braking: The invention of high velocity trains brought numerous issues with effectively slowing down due to the sheer speed and weight of trains. Friction based brakes were ineffective and required frequent replacement - the Electromagnetic brakes were developed as a means to reduce speed without friction. An electromagnetic field is placed through the wheel of the train, inducing eddy currents. These eddy currents repel the electromagnetic field and the wheel loses rotative speed.

● 1971 - Antilock Braking System (ABS): In 1971, Chrysler introduced a computerised wheel rotative speed sensor system that could detect when a wheel was rotating as a slower or faster speed than the others. Hydraulics controlled by a processor would

activate brakes on each wheel to maintain the same rotative speed. This increased the safety of vehicles, especially when turning or in wet surfaces.

Materials used in Braking Systems:

The properties of the materials used in braking systems are crucial to their effectiveness, these materials must be able to;

- Resist wear- Provide smooth, even contact to brake discs or drums- Resist large increases in temperature- Be easily serviceable

Most braking mechanisms are constructed using some form of steel due to its high durability, machinability and overall rigidness - these properties allow braking systems to undergo a large amount of stress and still effectively operate. Throughout the development and use of braking, a wide variety of materials have been used in braking shows and pads, these include:

Wood:

Wooden brake pads were the original material used as a friction material to slow vehicles. The type of wood commonly used was a hardwood due to its relative durability and closed pore structure, limiting the amount of dirt that could become trapped. Wood, as a material, is extremely easy to source and very inexpensive, however is subjectable to rotting. Overall wood does not have the coefficient of friction required for use on modern vehicles, however is extremely useful in applications where a low speed is involved. In comparison to other materials, there is no reason to use wood.

Asbestos:

Asbestos is a highly heat-resistant fibrous silicate mineral that can be woven into fabrics, it is most commonly used in brake linings and in fire-resistant or insulating materials. For use in brake pads, Asbestos strands are combined with a resin and formed into a the required shape. Asbestos brake pads are very effective at absorbing and dissipating heat due to its fibrous structure. One downside to Asbestos is while braking, the Asbestos brake pad undergoes friction which leads to the releasing of extremely fine dust particles, these particles become trapped within the brake housing and can cause major health issues for those who service a vehicle brake pads. Although Asbestos brake pads are effective at

dissipating heat and therefore efficient at braking, the associated health concerns far outweigh any positives that it provides.

Organic Materials:

Organic or Non-Asbestos Organic brake pads were developed as as an alternative to Asbestos, removing the danger of toxic dust being released when breaking. This material is composed of a number of naturally occurring materials including: glass, rubber, resin, kevlar and carbon - it is combined using a resin. The primary benefit of using a brake pad made of Organic materials other than Asbestos, is the much lower toxicity and general danger surrounding the dust it produces - this makes it much easier to dispose of used pads. Due to the composition of these brake pads, they are able to absorb and dissipate an extreme amount heat, leading to faster breaking. In comparison, these brake pads are a substantial amount cheaper to produce as well as being quieter, making them more suitable for commuting uses. However, Organic brake pads only operate effectively between a limited temperature and quickly lose their co-efficient when overheated. In addition, due to their softer nature Organic brake pads will wear faster in comparison to harder alternatives. Overall, Organic brake pads are an extremely effective choice for every-day driving purposes on motor vehicles, however are ill suited to performance driving or high load braking. Metallic:

Metallic brake pads are one of the most common brake pads available for general use. They can either be comprised completely of metal or partially - the pads are usually produced from an alloy of iron, copper and graphite. As the pads are metal they have a dramatically longer durability and lifespan in comparison to other pads, while also maintaining good heat dissipation, in addition to also providing a performance gain over organic pads. As they are easily mass producible, metallic pads are a much cheaper choice. However due to their much higher hardness, metallic brake pads can cause a much larger amount of wear on rotors, leading to higher maintenance. In addition, metallic pads work best between certain temperatures, after not being in use they must warm up before they can operate at their optimum performance. Overall metallic brake pads offer a strong compromise between cost, performance and maintenance - they are an extremely effective choice for motor vehicles that weigh more or are designed to go faster.

Ceramic:

Ceramic brake pads are produced from a dense ceramic material (essentially clay) with embedded copper fibre, filler material and bonding agents. These brake pads are commonly used on Formula 1 vehicles and trucks carrying large loads. Ceramic materials have an extremely high heat absorption and dissipation, making them suitable for use in performance racing and start-stop applications. Ceramic pads are also very wear resistant

and produce a limited amount of dust, allowing them to be used in long term applications. However, in comparison to the other types of brake pads, ceramics are extremely fragile and are easily cracked as well as being very expensive to produce. Overall, Ceramics are well suited to use in high performance vehicles, but other materials are much more well suited to use in every-day commuting.

Technological Developments:

Anti-Lock Braking System: An Anti-Lock Braking System (ABS) is an electronically controlled system designed to maintain steering ability and prevent skidding while a vehicle is under heavy braking. In a vehicle without ABS, when a large braking force is applied to the wheel, the wheel locks up and the vehicle loses traction to the load. This stops the driver from being able to turn the vehicle to dodge obstacles or pedestrians, usually ending in a collision. In a vehicle with ABS the controller monitors the rotative speed of all wheels, when a wheel begins to slow down or locks up, the controller releases the hydraulic system acting on the wheels brake pads and allows the wheel to begin rotating again. As the wheel is rotating, it has traction on the road surface and the vehicle is able to turn. Due to this, braking system are much more effective in achieving their purpose of slowing down vehicles, while also reducing the severe wear sudden braking can have on brake pads, rotors and tyres. With the ability to turn while braking, motor vehicles become safer for both the driver, other vehicles and pedestrians - reducing the number of collisions and injuries on the road.

Auto Emergency Braking: Auto Emergency Braking (AEB) is a vehicle safety technology designed to prevent or reduce the impact during a vehicular crash. The AEB system alerts the driver to an oncoming collision and assists them in applying full braking force. If the driver does not respond, the vehicle will independently apply brakes. In most forms of the technology a laser is emitted from the top of the windshield, aimed towards the front of the vehicle. When the laser strikes and object and is reflected back to numerous sensors positioned around the front of the vehicle. From the time measured between emitting and receiving, an on-board computer is able to determine the distance between objects and the relative velocity they are traveling at. Overall, Auto Emergency Braking drastically increases the safety of the vehicles that it is equipped with, reducing the number of collisions. Through priming the brakes when a possible collision is detected, a driver is able to access the full braking potential of their vehicle and stop in a much shorter distance.

Regenerative Braking: Regenerative Braking is a developing technology designed to convert the kinetic energy of a ca so that it can be returned to a vehicle’s battery. The technology is used in hybrid and electric cars due to their inclusion of an electric motor. Instead of using classical friction based disc brakes, the electric motor is turned off and instead acts as a generator. This slows the vehicle down as replenishes the battery. Overall, Regenerative

Braking is a more environmentally friendly means to breaking and increases the the distance capacity of electric or hybrid cars. It allows the owners of these cars to feel more environmentally conscious over their decision to not drive a fossil-fuel based vehicle. In terms of braking systems, it is an innovative concept that reduces the need for friction based brakes that also has similar stopping capabilities.

Bibliography:

Brake System Evolution: A History. (n.d.). Retrieved March 23, 2016, from

http://www.gregmonforton.com/evolution-brake-systems.html

Braking Systems History. (2009, May 20). Retrieved March 23, 2016, from

http://www.autoevolution.com/news/braking-systems-history-6933.html

History of Braking. (n.d.). Retrieved March 23, 2016, from

http://www.dbrake.com/braking-history.php

How Brake Pads Work. (2008, November 11). Retrieved March 23, 2016, from

http://auto.howstuffworks.com/auto-parts/brakes/brake-parts/brake-pads1.htm

What are The Best Brake Pads: Ceramic or Semi-Metallic? (n.d.). Retrieved March 23,

2016, from http://www.autoanything.com/brakes/the-best-brake-pads-ceramic-or-

metallic.aspx

Image 1 - http://www.dbrake.com/braking-history.php Image 2 - http://enginemechanics.tpub.com/14081/css/14081_85.htm Image 3 - http://engineeringbookworld.blogspot.com.au/2015/08/drum-brakes-type-of-mechanical-brake.html Image 4 - http://www.one-school.net/Malaysia/UniversityandCollege/SPM/revisioncard/physics/forceandpressure/pascalprinciple.html Image 5 - http://auto.howstuffworks.com/auto-parts/brakes/brake-types/disc-brake1.htm Image 6 - http://shiftperformance.blogspot.com.au/2015/07/anti-lock-braking-system_10.html

ASSESSMENT TASK MARKING RUBRIC

Part A – Engineering Report

10 - 9 8 - 7 6 - 5 4 - 3 2 - 0

Outlines the historical development of the braking system.

Detailed outline of the development of braking systems

10

Indicates the main features of the development of braking systems.

Indicates some features of the development of braking systems.

Indicates few features of the development of braking systems.

Shows limited or no evidence of investigation or inappropriate information is obtained.

15 - 13 12 - 9 8 - 6 5 - 3 2 - 0

Analyses and evaluates the changes in materials that have been used to manufacture braking systems.

Thoroughly analyses and evaluates the changes in materials that have been used to manufacture braking systems.

15

Sketches in general terms the changes in materials that have been used to manufacture the product.

Identifies materials that have been used in the manufacture of braking systems

Indicates some materials that have been used in the manufacture of braking systems

Shows limited or no evidence of investigation or inappropriate information is obtained.

15 - 13 12 - 9 8 - 6 5 - 3 2 - 0

Discuss how technological developments have influenced braking systems and affected people

Detailed discussion of how technological developments have influenced braking systems and affected people.

Outlines how technological developments have influenced braking systems and affected people.

Limited identification of how technological developments have influenced braking systems and affected people

Limited knowledge of how technological developments have influenced braking systems and affected people.

Shows limited or no evidence of investigation or inappropriate information is obtained.

14

The historical development section was detailed and accurate. Your use of images to support what you are saying was very good.

The section on materials was very good. You provided detailed information and conveyed your understanding and knowledge of engineering materials. There was a clear evaluation of each material and its suitability for use in modern braking systems.

The technological developments and their effect on people was excellent. You clearly explained each technological development and how it benefits people.

This was an excellent report Josh, well done

39/40

Part B – Hydraulic System

10 - 9 8 - 7 6 - 5 4 - 3 2 - 0

Demonstrate how fluid mechanics can be used to magnify forces, or move objects through a greater distance.

Detailed explanation of how the system operates.

10

Outlines how fluid mechanics can be used to magnify forces, or move objects through a greater distance.

Identifies how fluid mechanics can be used to magnify forces, or move objects through a greater distance.

Identifies some aspects of fluid mechanics.

Shows limited or no evidence of investigation or inappropriate information is obtained.

5 4 3 2 1 - 0

Be manufactured to a high standard (i.e. Neat and tidy).

Construction is completed to a high standard.

5

Construction is completed to a satisfactory standard.

Construction is complete however to a low standard.

Construction is incomplete or does not function.

Shows limited or no evidence of investigation or inappropriate information is obtained.

10 - 9 8 - 7 6 - 5 4 - 3 2 - 0

Complete the attached questions

Demonstrates a thorough understandin

Demonstrates a sound understanding

Demonstrates a satisfactory understanding of fluid

Demonstrates a poor understanding of fluid

Demonstrates a limited understanding of fluid

showing full working out using your hydraulic system.

g of fluid mechanics.

10

of fluid mechanics.

mechanics. mechanics. mechanics, or no information provided.

Your model was completed to a very high standard and clearly demonstrated a thorough understanding of fluid mechanics and its applications in engineering.25/25