In some places, your entire air brake pre-trip inspection hinges on this compentency :: being able to adjust a manual slack adjuster:
- A testing driver must either demonstrate how to adjust a brake equipped with a manual slack adjuster;
- OR verbally describe how to do this task.
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First and foremost, the wheels must be blocked and the brakes released. And the two key phrases in the sequencing of phrases are:
1) "I would turn the adjusting nut so the "S" cam rotates in the same direction as a brake application";
2) LAST - "The locking sleeve is re-engaged."
gloves, safety glasses, wheel chocks, 9/16" box end wrench, measuring device, pry bar, hammer (device to mark push rod at fix point if using the applied stroke method)
1) Block wheels, release brakes and ensure system pressure is above 100psi.
3) Disengage locking sleeve.
4) Establish adjusting nut direction.
The “S” cam must rotate in the same direction as a brake application.
If you turn the wrench more than 2 complete turns and it still hasn't gone tight, you are most likely turning the adjusting nut the wrong way.
5) Turn the adjusting nut until it goes snug. At this point, you've manually applied the brake.
6) Check that brake is manually applied. You should not be able to move the slack adjuster out of the brake chamber with a pry bar.
7) Back off the adjusting nut 1/3 to 1/2 turn.
8) Recheck adjustment.
With the pry bar method, push rod stroke should be between 1/2" & 3/4" inch (the width of your thumb nail).
With the applied stroke method, push rod stroke on a Type 30 brake chamber should be 3/4" to 13/4" inch.
9) Engage & check locking sleeve.