Timeline of developments in braking systems systems •
•
•
•
•
•
•
•
18th century external shoe brake, this brake consists of a curved wooden block or shoe which was designed to press against the rim of the wheels (generally wrought iron) this force was applied via a system of levers and linkages. ithout the developments of levers, and linkages this brake would not be possible. 18!"#s steam carriages also used hand operated brakes, still through levers and linkages to press wrought iron shoes to rub against cast iron wheels. The re$nement of wrought iron into cast iron improved the brake system from its predecessor. 18%& a compressed air brake was developed for f or the use on trains, it was made compulsory for all trains in 'ritain in 188,this system uses air pressure to charge tanks on each car, having full air pressure signals each car to release the brakes, reduction or loss of pressure signals for the brakes to be applied. This braking system relies upon the development of valves, to transfer the air pressure into the tanks. ate 18"#s the contracting band brake was developed, this brake operated on the principle of a band acting on a hub. This brake would not operate in reverse, was less e*ective in wet weather, dirt often became trapped between the hub and the lining which also reduced e*ectiveness. +t used a band of frictional material that tightens around a cylindrical piece of euipment to prevent it from rotating. This system relies upon the developments of high friction materials. 1"- was the introduction of the drum brake to which was una*ected by dirt and weather, as the brake shoes were enclosed within the drum. This braking system uses the friction of the lining being pushed against the inner surface of the drum to slow or stop the rotation of the wheel and axle. ithout the development of the drum to which encloses the brake shoes, lining, wheel cylinder and anchor, the drum brake would be less e*ective as it would be susceptible to exterior elements. 1" was when the hydraulic system was introduced to operate the rear brakes. This system uses brake /uid to transfer pressure to the braking mechanism to the controlling mechanism (in 11" most cars used separate and independent braking systems, hand operated lever and pedal mechanical or hydraulic hydraulic system). These systems rely rely upon the arrangement of the braking mechanisms. This system was originally developed developed in the early 1""s but was regarded regarded as new in 1&1. This system uses callipers to push brake pads pads against a brake disc0 the ensuing friction slows the rotation. These systems relied upon the development of the disc brakes and callipers. '2, anti3lock braking systems enable drivers to steer the vehicle while stopping, this is because this system prevent the wheels from locking during emergency braking situations. The abs system uses sensors which detect rapid deceleration0 a 456 monitors the information received from each sensor and ad7usts the brake pressure accordingly.
aterial
5roperties
6ses and applications rought iron was used in a range of things like9 carriages (wheel rims), fences, gates, railings, grilles and hardware.
rought iron
2oft, malleable, ductile, tough, can be work hardened, or alloyed.
:igh carbon steel
:eat treatable, hard, low ductility, brittle, high tensile strength, poor machinability.
:igh carbon steel was used in brake cable wire as well as things like9 springs, knives, tire reinforcement and rail steel.
asbestos
2ound absorption, average tensile strength, resistant to $re, heat, electrical and chemical damage, high co3e;cient of friction.
2pheroidal graphite cast iron
2oft, ductile, malleable, tough, machinable, strong in tension and compression
sbestos was used in the brake lining of both drum and disc brakes. +t is also used in thermal insulation, $re proo$ng, acoustic insulation, roo$ng and /ooring. 2pheroidal graphite cast iron is commonly used in9 brake discs, water and sewer lines, and
relationship rought iron was used in one of the most primitive braking systems for its malleability and softness which allowed it to be shrunk onto the rim using heat. rought iron is also tough and can be work hardened this made it a viable choice. :igh carbon steel was used in the wire for brake cable#s as these wire#s had a need for high tensile strength, the wire made from high carbon steel is also uite hard, and the properties can be altered further via heat treatments and alloys. sbestos was used in the brake lining due to its strength, heat resistance and high co3e;cient of friction
+t is due to its toughness and strength in compression that spheroidal
and can be heat treated.
=lexible, elastomer, corrosion resistant in the >braking environment#, tensile strength.
in automotive components when strength needs are higher than that of aluminium but don#t need steel e.g. class 8 trucks.
graphite cast iron is used in brake discs, it can also be heat treated to make the exterior harder.
'2 brakes evaluation. nti3lock braking systems were an innovation0 these systems aid in the prevention of the wheels of your vehicle from locking, this avoids uncontrolled skidding. This system relies upon the principles or threshold and cadence braking0 it does this faster and more precisely controlled than a driver. These systems improve the vehicle control that one has, and decrease the stopping distance on multiple surfaces, for surfaces that are loose e.g. gravel the braking distance will increase but vehicle control is still improved. These systems work as each wheel has a speed sensor which transfers the information (rpm) to the electronic control unit, if a wheel is rotating signi$cantly slower or faster than the others, the ?46 will ad7ust the pressure accordingly by either increasing the braking pressure or decreasing the pressure. '2 systems are very e*ective at increasing the amount of control that one has over a vehicle.
