Tractor Systems and Controls 3(2+1)

Lesson 22. Brake actuation methods

1. Purpose

Brakes can be classified on the basis of the purpose for which they are on the automobile:

a. Primary Brakes: These are used as the main brakes to stop the motion of the automobile.

b. Secondary Brakes: These are used as parking brakes to maintain the status of the automobile specially when parked on slopes or on even surfaces.

2. Location

The brakes can be located at the wheels or on the drive shaft of the transmission. The location of brakes on the transmission shaft not only gives the convenience of location and provides for equal braking effort on the braking wheels but locating these on the wheels provides dual advantage of having higher surface area for brake application and the greater area provides for better heat dissipation.

3. Construction

The brakes are classified into:

a. Internal expending shoe brakes

b. External contracting shoe brakes

c. Disc brakes

The internal expanding shoe brakes are also called the drum brakes and explained later. These types of brakes are most commonly used in tractors. But the new- age tractors are also coming with disc brakes.

The external contracting shoe brakes are external to the wheel and can be seen in case of railways.

4. Method of Actuation

The method of actuation decides as to how the braking effort from the point of application brake pedal, reaches tree brakes.

a. Mechanical Actuation- Most common in tractors.

b. Hydraulic Actuation- used in tractors with higher HP and motor cars.

c. Electric Actuation- use eddy currents for application of brakes.

d. Vacuum Actuation- applied in railways.

e. Pneumatic Actuation-applied in heavy vehicles and special purpose machines.