The brake system is arguably the most important system on a vehicle. A failure in this system can have a cataclysmic consequence which could lead to loss of life. The scary part is most people have little regard for the brake system and it is often overlooked and taken for granted. Let's take a look at the some of the parts that make up the system.
Brake booster
The advent of disc brakes has brought about the widespread use of the brake booster. Disc brakes require more braking force than drum brakes since the braking surface area of disc brkes is less than that of drum brakes. As it's name implies, the booster boosts the pressure you provide with your foot to the brakes thus making it easier to push the pedal and apply brakes. A sign of booster failure is when the pedal becomes hard and requires greater braking effort and it also becomes increasingly difficult to stop the vehicle. This needs to be attended to immediately since this can result in an uncontrollable situation.
Boosters are found in various guises from a vacuum in-line to remote hydrovacs and even hydroboosters which work on hydraulics. Vacuum boosters work off a vacuum feed from the inlet manifold in a petrol/gasoline powered vehicle to a pump either driven by the alternator, a v-belt or an electric pump. The latter are commonly found on diesel powered vehicles or vehicles with a high lift cam. Simply put, a booster works on the principle of atmospheric pressure over vacuum.
Non-return valve
This seemingly insignificant little valve is of great importance and is found in the vacuum line between the booster and the pump/inlet manifold. It is responsible for keeping air out of the booster and prevent the fuel/air mixture in the manifold from entering the booster, condensing and allowing the petrol/oil to contaminate and destroy the rubber parts in the booster.
Master cylinder
As the name implies, the master cylinder is the the part that masters all the other valves and parts in the circuit. The master cylinder pressurizes the brake system and allowes the other parts to work.
Brake lines
Brake lines may be likened to veins in the human body. They are made up of flexible rubber pipes and steel pipes ofter refered to as bundy. Brake pipes are responsible for carrying the fluid to operate the various components in the brake system.
ABS
Compensating valve
The compensating valve allows more brake pressure to be applied to the front wheels than to the back wheels in systems that have drum brakes at the rear and disc brakes in front. Typically, most vehicles have around 80% braking in the front whilst they only have around 20% at the rear. On pick ups / UTE's LDV's, there is a variable valve that allows more pressure to the back brakes as the vehicle is loaded with heavier loads so as to increase the braking to the rear. If this valve seizes, it usually allows too muck pressure to the rear brakes and causes the rear brakes to lock up when the brakes are applied.
Wheel cylinders (slave cylinders)
Wheel cylinders or slave cylinders as they are sometimes known, are found on drum brakes to the inside of where the wheel bolts onto the vehicle. The wheel cylinder or slave cylinder recieves pressure from the master cylinder and act on the brake shoes which then come into contact with the brake drum thus slowing or stopping the vehicle. Calipers
Calipers are found on disc brakes and have 2 - 6 pistons depending on the application. Calipers require a greater amount of pressure behind the pistons than wheel cylinders sincethe pinching or clamping action requires a greater force. Calipers work by allowing pressure fed from the master cylinder to act behind the pistons which in turn act up againsed the brake pad and in turn "pinch" or clamp the brake disc or rotor thus slowing or stopping the vehicle.
© 2008 Powerbrake and Steering |
