Drum Brake Primary And Secondary Shoes

Thus the rear shoe does most of the braking and the front shoes primary job is to engage the rear shoe.

Disasterpiece drum cam. The top of the secondary attaches to a pivot. When the leading or primary shoe hits the drum and wedges against it its pivot shoves backward on the rear shoe which may or may not be self energizing and forces it against the drum. The secondary shoe is the rear shoe and has the largest lining surface area.

A brake shoe can easily reach 4500 f from a 55 mph stop. In a duo servo brake system. When a brake pedal is released the wheel cylinders are returned to their inactive position by.

With this type of drum brake system neither shoe pushes against the other. This creates an internal expanding or self activated servo braking action. The primary brake shoe is the front shoe and normally has a slightly shorter lining than the secondary shoe.

The primary shoe tends to rotate with the brake drum which forces the secondary shoe against the brake drum surface. The lining of the primary and secondary shoes coming into contact with the rotating drum causes the friction necessary to bring the vehicle to a stop. Brake shoe anchors are attached to the backing plate and allow for the brake shoes to come into full contact with the drum providing an anchor for the momentum.

Some discount brake reliners use the same size lining front and rear but use different friction material. No the primary aka front shoe is always the short one or the one with the least amount of friction material. The secondary or rear shoe always has the most friction material.

This friction is transformed energy and produces great heat.