Parts of a Brake System – Automobile Brake Drum, Brake shoes, Brake linings

Common parts of braking system

The common parts of brake system
are listed below1. Brake drum
2. Brake shoes
3. Brake linings

Brake drum

Brake drums are commonly opened
in the inner side and closed on the outer side. The brake shoes present inside the brake drum are expanded and operate the brake. Due to the friction created while operating the brake system the brake drum is heated up and the temperature
of the drum is increased. To reduce this temperature, fins are located at outside the brake drum. The brake drum should not wear due to friction caused inside while rotating and it must have high thermal conductivity to dissipate heat quickly.Moreover it must be of less weight and it
must have enough strength. Brake drums are mostly made up of cast iron or nickel chromium steel alloy or Aluminium alloy materials.

Brake shoes

In each brake carrier plate two
brake shoes are provided. The brake shoes looks like in “T” shaped cross section. The left hand side of the brake shoe is called as the primary brake shoe and the shoe in the right hand side is is called as the secondary brake shoe. The bottom edges of the two brake shoes are connected with carrier plate through anchor pins. In
between the top edges of the brake shoe,brake cam or wheel cylinder is located.Both the brake shoes are in the pulling position with help of the retracting spring. Brake liners are fixed on the outer face of the brake shoes by riveting or by using the lining cement. The edge of brake shoe which presses the brake drum first is called as the leading shoe and the edge which presses the brake drum later is called as the trailing shoe.
Brake shoes are often made up of cast
iron or steel.

Brake linings

Brake linings are placed on the outer
face of the brake shoes. While pressing the brake pedal the brake linings are only in contact with the brake drum and reduces the speed of wheels. Therefore in brake linings the temperature reaches to about 350°C more and wear occurs.Hence the brake lining should be made
to withstand very high temperature and wear resistant and should not change its shape. Brake linings are classified into two types, they are1. Solid woven type
2. Molded type.

1. Solid woven type brake liner

It is made up of a non-metallic
twisted asbestos thread. The average
compression coefficient of this liner at
260°C is upto 0.4. This type of liner is easily tolerable up to 350°C. It is manufactured by asbestos threaded fibers which are combined with brass and zinc rods that could not be easily subjected to wear.These types of brake liners are used incars and heavy vehicles. These brake liners are attached to the brake shoes using riveting method.

2. Moulded type brake liner

This type of brake liners are made
of natural asbestos fibers with resin-
like synthetic paste by using moulding
technology. The average friction coefficient of this liner is 0.4. This liner could be operated at the temperature between 400°C to 450°C without any wear.

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