Wednesday, 28 September 2016

The Basics of Braking

Long time no see. But what I learned was about the braking mechanism of a car. As I read in my physics class about pressure, Bernoulli's theorem etc. etc., what got me interested the most was its application in braking mechanism. Before this I had never really considered the mechanics of breaks. Earlier I thought that car breaks were similar to the breaks in the cycles, however it's not quite simple as that.

The Brake hydraulics
A hydraulic brake system has fluid filled master cylinder and slave cylinders connected by pipes. The master cylinder transmits the hydraulic pressure to the slave cylinders when the pedal is pressed. When a person pushes the break pedal while driving, he actually depresses a piston in the master cylinder, forcing fluid along the pipe.
The fluid travels to each wheel and fills them, forcing pistons out to apply the breaks. Fluid pressure distributes itself evenly around the system. The combined surface 'pushing' area of all the slave pistons is much greater than that of the piston in the master cylinder.
Consequently, the master piston has to move several inches to move the slave pistons fraction of an inch it takes to apply the brakes. The effect is similar to the enhancement of force exerted by a fulcrum to lift a heavy object. 

Most modern cars are fitted with a twin hydraulic system, with two master cylinders in tandem, in case one should fail. Different cases can be employed with the twin hydraulic system such as one uses to power the front brakes while on used to power the rear breaks. Or each system works the front brakes and one at the back. Thus many combinations arise according to the braking power power estimated for the use of a particular type of a car.
Sometimes while braking so much weight may come off the rear wheels that the brakes may enter a lock and the car goes into a dangerous skid. Thus the rear breaks are made deliberately less powerful. To prevent this kind of situation in which locking occurs most cars have pressure limiting valve. It calms down when the hydraulic pressure in the breaks becomes too high thus preventing a lock.
Further cars may even have complex anti-lock system that is  "aware" of your car's braking trends during a particular run. Such systems apply and release brakes in rapid succession to stop them from locking.
So this is what I learned about the brake hydraulics. Hope this was informative!