What is a self energising brake?

Answer 1

A self energizing brake is one that uses the actual braking drag force to increase the force with which the brake is applied. Before the advent of power brakes, many cars, particularly heavy ones, were equipped with various forms of self energizing brakes in order to reduce the force required on the brake pedal. A simple type is the leading shoe drum break, in which the brake shoe leads it's pivot point. That is, the pivot point is at the trailing end of the brake shoe, considered from the direction of motion of the brake drum. In this design, applying the brake causes the brake shoe to drag against the brake drum, with more force then works to force the shoe against the drum with more force still, thus getting more breaking from the initial application force, multiply it by some factor.