The brake shoe is a bent piece of metal, on the outside of which the brake pad (friction-poor) is attached. It is mounted with many levers and springs on the carrier plate within the brake drum and adjoins the wheel cylinder, which is hydraulically actuated.
Function of the baking
As soon as the driver presses the brake, hydraulic fluid is pressed into the wheel cylinder by the braking power. The cylinder then expands and presses the jaws against the inner wall of the rotating brake drum. The resulting friction slows down the car.
The many levers and springs have two functions:
- On the one hand they automatically adapt the brake shoes to the inner wall of the wheel cylinder in order to avoid high wear.
- On the other hand, the jaws are coupled with the handbrake.
The brake pads are made of high-strength materials such as graphite, powdered metals such as lead, zinc and aluminum, and crushed cashew nuts.
Drum brakes are very susceptible at high temperatures (high heat development). This can significantly affect the brakes and reliable braking performance. If the brake drum is subjected to strong braking for a long period of time, it may cause the drum to expand. The jaws are pressed further and further outwards in order to produce the required braking effect. The expert speaks here of a '' long pedal ''. The driver must press the brake pedal very far down to achieve the same braking performance. This process often occurs when you are traveling with a trailer. They carry more weight and the brake has a lot more work to do.
Drum brakes are also susceptible to flooding and rust. As soon as water penetrates into the drum, it can be compressed between the jaw and the inside of the drum and has a negative effect on the braking time of the vehicle. The braking power is significantly impaired and only occurs once the collected water has evaporated through the heat. However, there are now various auto parts suppliers who have developed brake drums with a special protective coating. This protective varnish protects the entire brake drum against the effects of weathering.
Signs and signals from worn jaws
- There are unusual frictional and squeaking noises when turning
- Your vehicle pulls aside when braking
- Reduced braking power
Worn jaws can significantly reduce the braking force of your vehicle and lead to dangerously long braking distances. If you notice any of the above mentioned signals while driving, go to the nearest workshop immediately. Ignoring worn jaws can lead to costly repairs. For example, the brake drum could be damaged and then also replaced. Furthermore, worn jaws on the rear axle accelerate the wear of the front Bremsbel ge. This leads to a delayed braking reaction.
Important: Baking should always be changed in the set. A brake shoe set is always intended for one axle - so either the front or rear axle. Thus, the jaws are always worn evenly and a reliable braking performance is guaranteed. Brake shoes average between 45,000 and 100,000 kilometers, but should be checked by qualified personnel at each change.