SKEDSOFT

Introduction:
                Different types of brakes are used in different applications. Based on the working principle used brakes can be classified as mechanical brakes, hydraulic brakes, electrical (eddy current) magnetic and electro-magnetic types.
 

Classification of the brakes:

On the Basis of Method of Actuation

(a) Foot brake (also called service brake) operated by foot pedal.

(b) Hand brake – it is also called parking brake operated by hand.

On the Basis of Mode of Operation

(a) Mechanical brakes

(b) Hydraulic brakes

(c) Air brakes

(d) Vacuum brakes

(e) Electric brakes.

On the Basis of Action on Front or Rear Wheels

(a) Front-wheel brakes

(b) Rear-wheel brakes.

On the Basis of Method of Application of Braking Contact

(a) Internally – expanding brakes

(b) Externally – contracting brakes.

Mechanical Brakes

• Mechanical brakes are invariably based on the frictional resistance principles

•In mechanical brakes artificial resistances created using frictional contact between the moving member and a stationary member, to retard or stop the motion of the moving member.

Basic mechanism of braking

• An element dA of the stationary member is with the braked body moving past at velocity v.

• When the brake is actuated contact is established between the stationary and moving member and a normal pressure is developed in the contact region.

• The elemental normal force dN is equal to the product of contact pressure p and area of contact dA. As one member is stationary and the other is in relative motion, a frictional force dF is developed between the members.

• The magnitude of the frictional force is equal to the co-efficient of friction times the normal force dN.

• The moment of the frictional force relative to the point of motion contributes to the retardation of motion and braking.