When using the applied stroke method to check pushrod stroke, how much pressure should you apply to the service brakes?
- 60 – 80 psi
- 80 – 90 psi
- 90 – 100 psi ✓
- 100 – 125 psi
Answer: C. 90 – 100 psi
You should apply 90 – 100 psi to the service brakes when checking pushrod stroke with the applied stroke method.
Why this is the answer
The handbook states that most makers of automatic slack adjusters want the pushrod stroke checked with a 90 to 100 p.s.i. application. It also gives a workaround if you lack an application pressure gauge: shut the engine off, bleed reservoir pressure down until it sits between 90 and 100 p.s.i., then make a full application. That range is what the applied stroke method calls for, so the matching choice is the one between 90 and 100 psi.
Why the other answers are wrong
- A. 60 – 80 psi — 60 – 80 psi is below the 90 to 100 p.s.i. application the handbook describes for checking pushrod stroke.
- B. 80 – 90 psi — 80 – 90 psi does not reach the 90 to 100 p.s.i. range the handbook gives for the test application.
- D. 100 – 125 psi — 100 – 125 psi goes above the 90 to 100 p.s.i. application the handbook specifies for this check.
Remember it
Picture the gauge needle sitting in the nineties before you make the full application.