Beating The Drum For Drum Brake Systems
[Catalog:News] [Date:2021-4-9] [Hits:] [Return]
The most common service required for drum brakes is replacing the brake shoes. Some drum brakes provide an inspection hole on the back side, where you can see how much material is left on the shoe. However, it is recommended to remove the drum to perform a complete inspection on all the components inside the drum. Brake shoes should be replaced when the friction material has worn down to within 1/32˝(0.8 mm) of the rivets. If the friction material is bonded to the backing plate (no rivets), then the shoes should be replaced when they have only 1/16˝ (1.6 mm) of material left.
Just as in disc brakes, deep scores sometimes get worn into brake drums. If a worn-out brake shoe is used for too long, the rivets that hold the friction material to the backing can wear grooves into the drum. A badly scored drum can sometimes be repaired by refinishing. Where disc brakes have a minimum allowable thickness, drum brakes have a maximum allowable diameter. Since the contact surface is the inside of the drum, as you remove material from the drum brake the diameter gets bigger. A brake lathe is required to resurface the contact area of the drum. If the drum is heavily scored, damaged, warped or already over specification the drum will have to be replaced.
It’s not hard, then, to see why brake discs have become the preferred choice for car manufacturers, and why you don’t see performance cars running drums anymore. But the humble drum brake still has its uses for slower, less expensive cars and commercial vehicles, so it’s unlikely to be going anywhere any time soon. Some hybrid and electric vehicle manufacturers are also using drums to reduce rolling resistance and
weight.
Just as in disc brakes, deep scores sometimes get worn into brake drums. If a worn-out brake shoe is used for too long, the rivets that hold the friction material to the backing can wear grooves into the drum. A badly scored drum can sometimes be repaired by refinishing. Where disc brakes have a minimum allowable thickness, drum brakes have a maximum allowable diameter. Since the contact surface is the inside of the drum, as you remove material from the drum brake the diameter gets bigger. A brake lathe is required to resurface the contact area of the drum. If the drum is heavily scored, damaged, warped or already over specification the drum will have to be replaced.
It’s not hard, then, to see why brake discs have become the preferred choice for car manufacturers, and why you don’t see performance cars running drums anymore. But the humble drum brake still has its uses for slower, less expensive cars and commercial vehicles, so it’s unlikely to be going anywhere any time soon. Some hybrid and electric vehicle manufacturers are also using drums to reduce rolling resistance and
weight.