Which is NOT true about leading-trailing type drum brakes?

• A. They are self-energizing
• B. They have a primary and secondary shoe
• C. They require adjustment
• D. They are simpler in design

Answer: (A)

The assertion that leading-trailing type drum brakes are self-energizing is not true. Leading-trailing drum brakes are designed with one shoe acting as a leading shoe and the other as a trailing shoe when the brake is applied. This design differs from that of self-energizing brakes, where the rotation of the drum helps push the shoes against the drum more effectively, enhancing the braking force through an increase in friction. In a leading-trailing setup, while there is some assistance from the motion of the drum, it does not exhibit the same level of self-energization as other drum brake designs might.

The other statements are accurate regarding leading-trailing drum brakes. They consist of a primary and secondary shoe, which serve distinct functions during braking. Adjustments are necessary over time to maintain proper clearance and ensure optimal performance as brake components wear down. Additionally, the design of leading-trailing brakes tends to allow for simpler mechanics compared to other more complex braking systems, making them easier to manufacture and maintain.