If your vehicle is equipped with automatic slack adjusters, why must you fully apply the service brakes regularly?
- To keep the slack adjusters properly adjusted ✓
- To prevent the slack adjusters from corroding
- To get a better feel for how these brakes respond
- To prevent a clevis from seizing over time
Answer: A. To keep the slack adjusters properly adjusted
You must fully apply the service brakes regularly to keep the slack adjusters properly adjusted. Automatic slack adjusters only take up brake wear as the brakes are actually used, so routine full brake applications are what keep them in adjustment.
Why this is the answer
The handbook explains that automatic slack adjusters, as the name says, adjust for brake wear as the brakes are used, while manual slack adjusters stay put until someone adjusts them by hand. That tells you the automatic units depend on the brakes being applied to do their job, so regularly using full service brake applications is what keeps them properly adjusted. Nothing in the passage says this has anything to do with corrosion, with how the pedal feels, or with a clevis.
Why the other answers are wrong
- B. To prevent the slack adjusters from corroding — The passage never links brake applications to corrosion; it only says automatic slack adjusters take up wear as the brakes are used.
- C. To get a better feel for how these brakes respond — Getting a feel for the brakes is about your own familiarity with pedal response, and the handbook gives no such reason for applying the service brakes.
- D. To prevent a clevis from seizing over time — A clevis seizing is not mentioned anywhere in the passages, which talk about wear adjustment and pushrod stroke, not seizing components.
Remember it
Automatic adjusters only work while the brakes work — every full brake application is the adjuster doing its job.