Braking system

Brakes is one of the most important element of automobile. There are many types of brakes available in automobile industries. Theses are primary brake, Secondary brakes, vacuum brake, air brake, disk brake, drum brake etc. 

The classification of brakes are as follow. 

According to the purpose:

1. Primary or service brake:

This brake is used when the vehicle is in running condition to stop or slow down the vehicle. This is the main braking system, which is situated in both rear and front wheels of the vehicle. 

2. Secondary brakes:

Secondary brakes, which is also known as parking brake or emergency brake , are used to keep the vehicle stationary. It is generally operated by hand, so also known as hand brake. The main function of this brake, is to keep the vehicle stationary when it is parked. 

According to the construction:

1. Drum brake:

In this type of brakes a drum is attached to the axle hub whereas on the axle casing is mounted a back plate. The back plate is made of pressed steal sheet. It provide support for the expander, anchor and brake shoes. It also protect the drum and shoe assembly from mud and dust. It also known as the torque plate because it absorbed the complete torque reaction of the shoe. Two brake shoe is mounted on back plate with friction linnings. On or two retractor spring are used to seprate brake shoe from drum when the brakes are not applied. The brake shoe are anchored at one end, whereas on the other ends force is applied by means of some brake actuating mechanism which forces the brake shoe against the revolving drum, so the friction force is generated between drum and the shoe and brake applied.

An adjuster is also provided to compensate for wear of friction lining with use. This brakes are widely used in motorcycle and the cars.

2. Disk brake:

Disk brake consists of a cast iron disc bolted to the wheel hub and a stationary housing called caliper. The caliper is connected to some stationary part of the vehicle and it cast in two parts, each part containing a piston. In between each piston and the disc there is a friction pad held in position by retaining pins, springs plates etc. There are arrangements in the caliper for the fluid to enter or leave each housing. There passages are also connected to another one for bleeding.  Each cylinder contains a rubber sealing ring between the cylinder and the piston.

When the brakes are applied, hydraulically actuated piston move the friction pads into contact with the disc, applying equal and opposite forces on the later. On releasing the brakes, the rubber sealing rings act as return springs and retract the pistons and the friction pads away from the disc.
reference:www.mech4study.blogspot.com