Hydraulic Unit In Brakes

Let's talk about  some basics of the braking system in automobiles. There are brakes on all the four wheels of a car. Now the brakes at the rear are the drum brakes and the ones at front are the disc brakes. The front brakes have to be very strong and efficient because when brakes are applied, the whole weight of the car is thrown on the front brakes . All the brakes in the car are connected by a hydraulic system.
 Let's go into some details about the hydraulic system. It has a push rod, a master cylinder containing the piston and return spring, a fluid reservoir, slave cylinders which have the piston and spring, brake shoes and the rotating drum.The master cylinder is connected to the slave cylinders by brake lines which contain the working fluid. The working fluid is usually a glycol ether or silicone based  product.
  • When you apply your foot on the brake pedal. it transmits a force to the master cylinder due to which the return spring exert pressure in the forward direction .
  • This pressure is transmitted to the slave cylinders where the pistons expand and apply force on the brake shoes which presses against the spinning drum.
  • There is a fluid reservoir which is used for continuously filling the master cylinder with the working fluid. 
Once you release your foot from the brake pedal, the master and the slave pistons return to their original position. The brake shoes are then released from the drum.
Unless there are any leaks, the fluid does not enter or leave the the system. We can call it a closed system. However there should be a lookout for cracks when the fluid gets contaminated or when you mix two types of fluids.

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