Repair Procedures and Adjustments
Core concepts
Repair procedures require correct torque, cleanliness, and adherence to manufacturer specifications. Know how to replace a spring brake chamber safely (cage it, block the wheels, follow the release procedure), how to adjust or replace automatic slack adjusters, and how to bleed hydraulic systems properly. Understand that brake linings and drums must be replaced in axle sets and that contaminated linings (oil/grease) must be replaced, not cleaned.
Know the importance of using the correct fasteners and torque values, and of inspecting for cracks, wear, and corrosion. Understand that after any repair, a functional test is required: build pressure, check for leaks, test the parking brake, and road-test where appropriate.
Traps in questions
- Reusing contaminated linings or turning drums beyond the manufacturer's limit.
- Failing to cage a spring brake before removal.
- Adjusting an automatic slack adjuster manually without correcting the underlying foundation brake problem.
- Skipping the post-repair leak and function test.
Rule of thumb
Replace linings and drums in axle sets, never clean oil-soaked linings, and always perform a leak and function test after any brake repair.