Final answer:
Leading shoes are installed such that they are applied in the same direction as the drum's forward rotation in a drum brake system, enhancing the braking force through a self-energizing effect.
Step-by-step explanation:
Leading shoes are installed so that the direction they are applied is the same as the forward rotation of the drum. Drum brakes in a vehicle's braking system use leading shoes for creating friction against the drum to slow down the vehicle. When the brake pedal is applied, the leading shoe is pushed into the drum which is rotating in the direction of the wheel's movement. This results in a self-energizing effect, as the rotation of the drum pulls the shoe into greater contact with it, thereby increasing the braking force. This type of brake shoe is contrasted with trailing shoes, which are less effective in creating stopping force when the vehicle is moving forward since they are applied in the opposite direction of the drum's rotation.