Landoll L20 Series, Operator'S Manual, Page: 28 / 48

5. The push rod stroke should be 1 1/2" to
2" with an 80 to 90 PSI service brake
application.
6. Measure the movement of the push rod
from the completely released position
to the applied position by marking the
push rod where it exits the air chamber
before and after application.
7. If the brakes have been running tight,
the control arm location should be
checked.
WARNING
IF THE ADJUSTER APPEARS NOT TO
BE OPERATING, CHECK THE FOUN-
DATION BRAKE FOR PROPER FUNC-
TION AND ELIMINATE ANY BINDING.
RECHECK THE AUTOMATIC SLACK
ADJUSTER. IF THE ADJUSTER IS NOT
FUNCTIONING, THE UNIT MUST BE
REPLACED BECAUSE FAILURE OF
PROPER ADJUSTMENT FUNCTION
WILL RESULT IN LOSS OF BRAKES.
b. Replacing Slack Adjuster (See Figure
4-4)
1. Chock wheels to prevent vehicle from
rolling. Release spring and service
brake. Air chamber push rod must be
fully released .
2. To maintain a fully released parking
brake, a minimum of 80 psi reservoir
pressure must be maintained. If air
pressure is not available, the spring
brake must be manually caged.
3. Remove the existing slack adjuster and
clevis - DO NOT REMOVE EXISTING
JAM NUT.
4. Install the new clevis (with 1/2" pin)
onto the push rod up to the jam nut -
DO NOT TIGHTEN JAM NUT.
5. Fit the installation guide over the s-cam
splines so the 1/2" pin slots face the air
chamber.
6. Swing the guide into the clevis until the
appropriate slot totally engages 1/2"
pin.
7. Observe the guide pointer arrow:
If the guide pointer is above the clevis,
rotate clevis counterclockwise for
alignment.
If the guide pointer is below the clevis,
rotate clevis clockwise for alignment.
8. Reposition clevis until the guide pointer
aligns with the clevis pointer.
9. Verify by engaging 1/4" pin through the
clevis and guide.
10. Tighten jam nut to 50 ft.-lbs. torque
min.
11. Remove the guide from S-cam shaft.
12. If the push rod threads extend
through the clevis more than 1/16",
remove clevis and cut rod to length.
13. If the push rod is not fully engaged in
clevis body, install a new push rod -
cut to length.
14. Install the slack adjuster on the
S-cam shaft.
15. Rotate the manual adjuster shaft
clockwise until the slack adjuster arm
holes align with the clevis. Install 1/2"
and 1/4" pins and cotter pins.
c. Adjusting Crewson Brunner Slack Ad-
juster
1. Rotate the manual adjuster clockwise
until brake shoes contact drum.
2. Back off manual adjuster 1/2 turn.
(counterclockwise)
3. Manually uncage the spring brake.
4. Build up vehicle air pressure.
5. Fully apply and release the brakes
several times to check for adequate
clearance to all adjacent components.
6. Measure the distance from air
chamber to 1/2" pin. Apply brakes with
80-90 psi air pressure and remeasure
distance to 1/2" pins.
7. The stroke (difference of these two
measurements) must be less than 2
inches.
4-8