Introduction of Primary And Secondary Brake Shoe
Simple Drum Brake System
A simple drum brake system uses Primary (leading) and Secondary (trailing) brake shoes operated by a single slave cylinder. Usually only on the rear wheels of cars, or now the front wheels of tandem trailers. The front brake shoes tend to wedge and become a self-servo brake without power assist. Trailing basically only becomes a forefoot when reversing, with this self-servo effect. The same applies to trailer electric brakes.
Considerable extra braking comes from having each shoe as a leading shoe with their own slave cylinder. (For clockwise drum rotation in the picture).They become useless in reverse, and thus need power assist to work in reverse with friction from just slave cylinder pressure because there is no wedging, self-servo effect in reverse (anti-clockwise drum rotation).
You can see that there are many brake shoe configurations and I was specifically referring to the Simplex and Duplex type of drum brake. The Bendix type that is used in American cars is mostly the duo-servo type.
Where to buy brake shoe?
Longway Machinery is a leading brake chamber manufacturer & factory that focuses on automatic slack adjuster OEM. We solemnly promise to provide your products with excellent quality, reasonable prices and the highest cost performance.
Welcome to choose Longway Machinery - a leading brake chamber manufacturer & factory that focuses on automatic slack adjuster OEM.