In an S-cam drum brake, which of the following is connected to the brake spider?
- Brake shoe ✓
- Pushrod
- Slack adjuster
- Brake chamber
Answer: A. Brake shoe
The brake shoe is the component connected to the brake spider.
Why this is the answer
The handbook says the brake spider is the base that the brake shoes mount to in an S-cam brake. The shoes sit inside the wheel and are held in position with hardware such as anchor pins and anchor springs. That makes the shoe the listed part tied to the spider. The other listed parts belong to the air and linkage side: the pushrod stroke works on the slack adjuster at the camshaft end, and the brake chamber is listed as a separate component.
Why the other answers are wrong
- B. Pushrod — The pushrod is part of the air-brake linkage; its stroke acts on the slack adjuster, so the passages do not place it on the spider.
- C. Slack adjuster — The slack adjuster is attached to the end of the camshaft and is moved by the pushrod stroke, not described as mounted to the spider.
- D. Brake chamber — The brake chamber is listed as a separate air-brake component whose pushrod stroke operates the linkage, not as a part fixed to the spider.
Remember it
Picture the spider as the shoe rack inside the wheel: the shoes mount to it.
Official handbook: Official MTO Air Brake Handbook, Foundation Brakes – "S" cam brakes