Backing Plates

How Do Backing Plates Work?

A typical wheel has two curved brake shoes which are mounted onto a backing plate made of steel.

The brake shoes themselves resemble a comma-like shape, with friction material visible across the outside curve. They are attached to either side of a brake plate.

This general setup is placed inside a cast iron drum that rotates in accordance with the wheel.

Brake shoes are kept away from the drum when brakes aren’t in use by the presence of springs, which play an important role in maintaining distance.

Come time to brake, pressure from the pedal translates to a hydraulic fluid in the brake lines. This enters the wheel cylinder – fixed at the top of a backing plate – and causes its spring-loaded pistons to move outwards.

The resulting movement sees the brake shoe pushed up against the inside of the brake drum.

That friction material on its outer edge then meets the inner surface of the drum and brings the car to a halt.

While the role of backing plates may sound minor, their presence is pivotal. None of the above would work without their presence, which underpins everything.

When it comes to braking they are perhaps the most critical component.