How brake drums work – Bendix gives a rundown

Brake drums might be an older braking system compared to the now favoured disc brake set-up, but nonetheless they’re quite complex, meaning that maintenance on these systems is best left to the professionals.

A drum brake consists of 10 main components, the drum, backing plate, the wheel cylinder and pistons, the brake shoes, adjustment screw, the hold down springs and the return springs. Drum brakes that act as the handbrake as well, will also include a brake strut bar and brake lever.

Brake drums are quite complex and comprise of 10 main components.

The general operation of brake drums works on similar principles to disc brakes, with two brake shoes creating friction against the drum surface to slow down the vehicle. When the brake pedal is applied, brake fluid from the master cylinder makes its way through the brake lines and into the wheel cylinder located within the brake drum. The brake fluid then pushes the two pistons within the cylinder outwards, which in turn moves the brake shoes against the inner lining of the brake drum.

Brake fluid pushes the piston within the wheel cylinder outwards, in turn moving the brake shoes against the inner lining of the brake drum.

As the drum brake is directly mounted to the wheel hub, this generates the friction required to slow the rotation of the wheel and the speed of the vehicle. The return springs within the mechanism work to reinstate the brakes shoes to their original position once the brake pedal is released, while the hold down springs on either side keep the brake shoes in place at their pivot point.

The return springs within the mechanism work to reinstate the brakes shoes to their original position once the brake pedal is released.

The adjuster screw at the bottom of the mechanism gradually unwinds as the brake shoes wear, to close any increased distance between the brake shoe friction material and the inside of the brake drum, allowing for consistent brake pedal feel and braking response. The adjuster screw needs to be manually reset at every drum brake service.

The adjuster screw needs to be manually reset at every drum brake service.

For the drum brake that also doubles as the handbrake, there is a brake lever within the drum that allows the brake shoes to be applied independently of the hydraulic braking system via the handbrake lever. The brake strut sits between both shoes and the brake lever on one side; this component works to equally apply both brake shoes when the handbrake is engaged.

Bendix's latest Brake Drum release targets selected utility vehicles and some light car passenger models.

Bendix offer a range of brake drum options to suit a variety of vehicles along with brake shoes that offer superior stopping power, coupled with low noise and dust performance, and durability.

Bendix's range of brake shoes are developed specifically for local conditions to provide fast, reliable and economical brake shoe replacement.

Within its Ultimate 4WD™ range, Bendix also has drum brake upgrade kits that a suitable for a wide range of popular four-wheel drive wagons and utility vehicles to enhance their stopping power.

The Bendix Ultimate 4WD™ Brake Drum Upgrade Kit includes a pair of Ultimate 4WD™ Brake Drums, compatible Ultimate 4WD™ Brake Shoes and a can of Bendix Cleanup for a fuss-free installation.

To view a video clip explaining brake drum operation, click here or scan the QR code below: