What is a duo-servo drum brake system?

A duo-servo drum brake system is a type of drum brake design that enhances braking efficiency by using two brake shoes that engage the drum in such a way that they assist each other during braking. When the brakes are applied, the leading shoe rotates in the direction of the wheel, which pulls the trailing shoe into greater contact with the drum, increasing the braking force. This design is commonly found in rear drum brakes of vehicles, providing better stopping power and reduced stopping distances compared to single-servo systems. The duo-servo mechanism is particularly effective during hard braking situations.