The braking system is one of the most important parts of a vehicle. It is what allows the driver to bring a moving automobile to a stop or slow it down within a safe distance. Everyone knows that you push the brake pedal to make this happen, but a disturbingly high number of people are unfamiliar with how the braking system works. Below is a look at the types and main components of a modern braking system, and describing how each functions.
Dual-Circuit Braking System
This type of braking system has each circuit acting on both of the front wheels, and one of the rear ones. When the brake pedal is pressed, it forces fluid from the master cylinder through the brake pipes and to the slave cylinders placed at the wheels. The master cylinder comes with a reservoir to keep it full at all times.
In a modern car, there are brakes attached to all four wheels, which are manipulated using the hydraulic system. The brakes may be of either the disc or the drum type. The front brakes are more vital to stopping the vehicle, due to the fact that when braking during forward motion, the car’s weight gets thrown to the front. For this reason, lots of cars have disc brakes in that area for greater efficiency, and drum brakes for the rear wheels. Full-fledged disc braking systems are used mainly on high-performance cars, while all drum brakes are mainly seen in smaller and older vehicles.
The brake circuit using hydraulics has a master cylinder filled with fluid, and smaller slave cylinders connected to this one via pipes. The master cylinder sends out hydraulic pressure when you press the brake pedal. This pushes fluid into the slave cylinder located at each wheel, filling it and forcing its piston out towards the brake.
The pressure throughout the system is maintained evenly. The sum of the “pushing area” achieved by the slave pistons is a lot more than that of the master cylinder, which means the master piston must move several inches to make the slave pistons travel even a fraction of an inch. However, the brakes end up exerting much greater force.
In most modern cars, you have twin hydraulic circuits, and there are two master cylinders working at once, so that one can take over if the other fails. Moreover, rear brakes are deliberately kept less powerful than front ones, because during heavy braking, a significant amount of the car’s weight comes off the rear wheels, and this is often enough to cause them to lock. In advanced cars, there are often complex anti-lock setups, which can sense it when one or more of the wheels is locking.
Power assistance is what lets the driver apply the brakes with less effort than otherwise. This arrangement uses a direct-acting servo that is fixed between the master cylinder and the brake pedal. That way, if the servomechanism ever failed, the pedal could still be used to manipulate the master cylinder.
The brake pedal functions by pushing a rod which is meant to exert pressure on the piston in the master cylinder. The pedal also influences a set of air valves when pressed, closing the one linking the rear of the diaphragm and the manifold when pressed. At the same time, it also allows air to enter by opening another valve. The high pressure from that pushes diaphragm onto the master cylinder piston, increasing braking power. When you release the pedal, the pressure behind the diaphragm drops and falls back in place.
Disc Brakes and Drum Brakes
Disc brakes of the basic kind have two pistons, and a disc, which turns along with the wheel. The latter has a caliper straddling it, which has small hydraulically worked pistons connected to the master cylinder. They press on the friction pads, which clamp down on each side of the disc to slow or halt the wheels’ spinning. Fluid pressure from brake applications is what causes this to happen.
Drum brakes comprise hollow drums that turn along with the wheel. Two curved shoes are present inside each drum, and these carry frictions linings. They are forced outwards when hydraulic pressure is applied transmitted from the master cylinder, and in turn press the linings on the drum’s interior surface to stop or slow the wheel’s spinning.
This component of the brake system is not connected to the hydraulic cylinder. It has an arm and a lever inside the brake drum; both are operated via a cable running all the way from the lever next to the driver’s seat. The typical handbrake functions mechanically, and its limited braking power means it is better suited to use in parking.