Final answer:
No, a non-servo style (leading/trailing) drum brake unit does not have any servo action. Servo action is a self-amplifying effect present in servo drum brakes, which increases braking force without additional effort. However, non-servo drum brakes rely solely on hydraulic and mechanical force.
Step-by-step explanation:
A non-servo style drum brake, commonly known as a leading/trailing drum brake, does not have any servo action. The servo action refers to the self-amplifying effect that occurs in servo drum brakes where one shoe (the primary) is positioned to be more effective when rotating forward. This causes the shoe to press harder against the drum, increasing braking force without additional pedal effort. However, in a non-servo setup, both brake shoes are symmetrical and do not produce this self-energizing effect. Instead, the braking force is solely a result of the hydraulic pressure applied by the master cylinder and the mechanical force from pushing the pedals; thus, it does not benefit from any servo mechanism to amplify the braking force.