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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A course for truck, bus & RV drivers operating a vehicle fitted with air brakes.
This self-paced course gives you:

• more than 100 practice test questions with feedback;
• EASY step-by-step instructions how to conduct a pre-trip inspection on an air brake system;
• DETAILED rules to use air brakes and brake downhill with a large vehicle safely;
• step-by-step instructions and precise wording for pre-trip inspection of trailers with airbrakes;
• explained SIMPLY to you is the tractor protection system and its components.

Illustrations, checklists, & cheat sheets ensure your success



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.

2) Determine brake are in fact out-of-adjustment using either the pry bar or applied stroke method.

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.

In-Cab CDL Air Brake Checklist
This checklist will ensure that you know the numbers and pass your CDL Air Brake In-Cab Pretrip Inspection first time!

* Easy to use checklist to show you which test you must do for the IN-CAB CDL AIR BRAKE INSPECTION

* Detailed sample test to show you how the tests are completed step-by-step

* Easy to use guide to move through all the rigamarole of CDL manuals

Get yours today,  PASS & start your new career!!