This is part of my Brief Guide To Brakes series – a result of my research for Edinsolar, the University of Edinburgh’s solar vehicle team.
HOW IT WORKS
• drum shoes pushed into the sides of the drum cylinder
• friction slows down the drum cylinder
• return springs pull drum shoes away from cylinder to release brakes
Often the drum brake contains 3 main parts:
Main Drum Brake
• piston pushes drum shoes
Emergency/Parking Brake
• pull on a lever attached to steel cables
• steel cables pull shoes directly against the drum
o completely mechanical, no dependence on the hydraulics
Self-Adjusters
• as the shoe pads wear away, the piston needs to push the shoes further to reach the drum
• after a certain level of use, the automatic self-adjusters move the rest position of the shoes so they are closer to the drums and have less to travel again
Blue Pigeons 