A type of drum brake mechanism. The “leading” brake shoe is applied in the direction of the drum rotation. This can either be a single leading shoe or a double (twin) leading shoe design and refers to the number of cams used to activate the braking force. When you apply the brakes with a single leading shoe, one cam pushes the same side of both brake shoes out to make contact with the brake drum. When you apply the brakes with a twin leading shoe, two cams (one on each end of the brake shoes) push both ends of the brake shoes out to meet the drum and results in stopping force.
