GERALD's TIRES & BRAKES

 

The brake drum is a heavy flat-topped cylinder, which is sandwiched between the wheel rim and the wheel hub. The inside surface of the drum is acted upon by the linings of the brake shoes. When the brakes are applied, the brake shoes are forced into contact with the inside surface of the brake drums by the wheel cylinders which slows the rotation of the wheels.

The drums are usually covered with fins on their outer surfaces to increase cooling. They are not cooled internally, because water could enter through the air vent cooling holes and braking would then be greatly impaired.

Drum brakes are found on the rear wheels of older cars, but they are increasingly being phased out in favor of rear disc brakes. Drum brakes were standard equipment on all four wheels of most cars until the early 70's.