33
MAINTENANCE
Slack Adjuster
Crewson Brunner Automatic Slack
Adjuster
WARNING
This section is valid only for Crewson Brunner
slack adjusters. If your Transport is equipped
with any other OEM’s slack adjusters, contact
the appropriate OEM for maintenance and
adjustment instructions.
Recommended Preventive Maintenance
Every Three Months or 25,000 Miles
1. Check the condition of the brakes, including
drums, shoes and linings, cams, rollers, bearings, etc.
2. Check for structural damage of the automatic slack
adjuster housing and condition of the boot for cuts, tears,
etc. Replace if necessary.
3. After allowing brake drum to cool to room tem-
perature, check for correct chamber stroke. See chart
below for correct stroke measurements.
Chamber Type
Maximum Stroke
12..........................
less than 1-3/8"
16..........................
less than 1-3/4"
20...........................
less than 1-3/4"
24...........................
less than 1-3/4"
30...........................
less than 2"
Every Six Months or 50,000 Miles
The Crewson Brunner automatic slack adjust-
ers are factory lubricated and extensively sealed to pro-
tect against dirt, water, salt and other corrosive elements.
Nevertheless, periodic lubrication is recommended.
1. Grease the automatic slack adjuster.
(a) The styles of grease plugs or reliefs may
vary according to models.
(b) See Crewson Brunner service data for the
approved types of lubricant.
2. Test adjuster function.
Figure 28. Slack Adjuster Lubrication Points
Testing Adjuster Function
Check the operation of the slack adjuster by observ-
ing the auto-check indicator during several applications
of the brakes. The pointer should return to the “Home”
position and not go into the red zone when the brakes
are applied. Another way to check the operation is to
measure the maximum stroke during brake application.
If maximum stroke at 90 psi of the Crewson Brunner
automatic slack adjuster is less than the distance in the
Maximum Stroke Chart below, the adjuster is func-
tioning properly.
Chamber Type
Maximum Stroke
12...........................
less than 1-3/8"
16............................ less than 1-3/4"
20............................ less than 1-3/4"
24............................ less than 1-3/4"
30............................ less than 2"
Figure 29. Measuring Maximum Stroke
Full OFF Position
Full ON Position
AUTO-CHECK
H
O
M
E
AUTO
-CHECK
CREWSON
BRUNNER
Boot
Auto-Check
Indicator
Grease Fitting
(Far Side)
Hex Extension