Page 231 - Driving Commercial Vehicles Manual+

chapter 10 — vehicle and air brake pre-trip inspections

Class 3 Return to cab.
pre-trip inspection
Check that air pressure is at least 100 p.s.i. (690 kPa).
Check that parking brakes are released.
driving tip Make a full brake application (90 to 100 p.s.i., 620 to 690 kPa) and hold it for

one minute:
Make sure the spring brakes
are released before making • Check to ensure that, after the initial pressure drop, air loss is not more than
a heavy brake application three p.s.i. (20.7 kPa) per minute.
to avoid compounding the
brakes. • Check that there are no audible air leaks.
Set parking brakes. Remove wheel blocks.

6. Brake response, tug and steering wheel slack tests
driving tip
Perform these steps:
Check brake adjustment 1. Depress clutch. Shift transmission into neutral and start engine.
when you are underneath
the truck. 2. Ensure air pressure is up to operating range.
3. In low gear, gently tug against the parking brakes. The brakes should
prevent the truck from moving.

4. Release all brakes.
5. Move the truck ahead slowly and apply the foot brake to check brake
response.

6. Move the steering wheel to check for excessive slack or lash (play).

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