When the brakes are applied, circuits send compressed air from the storage tanks to front and rear service chambers that push the brake shoes into the brake drums, thus slowing down the vehicle. Semis ...

There is a reason that every manufacturer eventually dropped the drum brake design. When cars had 100 horsepower drum brakes ...

Five years ago, when federal authorities announced that stopping-distance rules for heavy tractors would get stricter, there was talk that this would finally cause a conversion from drum brakes to air ...