In a single anchor duo-servo drum brake system, which shoe does most of the braking?

In a single anchor duo-servo drum brake system, the secondary shoe is responsible for most of the braking. This occurs due to the design and operation of the braking system. When the brakes are applied, the leading shoe pivots against the anchor point and makes contact with the drum, causing it to push the secondary shoe outward against the drum as well.

The secondary shoe has a greater mechanical advantage because it is positioned in a way that receives additional force when the brakes are activated. This setup allows the secondary shoe to exert more force on the drum, thus contributing significantly to the overall braking power exerted by the system.

Understanding this mechanism is crucial for identifying the proper function of each shoe in the brake assembly, which is vital for diagnosis and repair in brake systems.