CAT: 8612 November 2019
Page 233
PREVENTIVE MAINTENANCE
AUTOMATIC SLACK ADJUSTERS
During preventive maintenance on an in-service brake, check/measure
both the free stroke as described below and the adjusted chamber stroke
as described on page 234.
FREE STROKE MEASUREMENT
Your Kenworth may be equipped with automatic brake (slack) adjusters.
Periodically, brake adjustment should be checked using the following
procedure:
1. Check brakes when the temperature of the brake linings are cool and
the system air pressure is at 827kPa (120psi) maximum.
"X" Released Position
"Y" Applied Position
Free Stroke = Y Minus X
Drum brake free stroke
must be 12.7-15.9 mm
(1/2-5/8 in)
"X"
"Y"
Disengage a pull
pawl or remove a
conventional pawl
2. Release the parking brakes to allow the slack adjusters to retract.
3. Measure the retracted pushrod length from the face of the brake
chamber to the centre of the pushrod pin.
4. Have another person apply and hold the brakes one full application,
measure the same distance.
5.
The difference is the pushrod travel distance (applied stroke).
Verify the result is within the correct range (see Table on page 234 - Brake
Adjuster Application). Correctly installed and functioning brakes (automatic
slack adjusters) will produce the strokes listed for each chamber type. Test
the vehicle to ensure that the brake system is working correctly before
returning a vehicle into service.
Summary of Contents for T410
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Page 331: ...SECTION THREE MAINTENANCE LUBRICATION SCHEDULES ...
Page 369: ...SECTION FOUR SERVICE RECORDS ...
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