BRAKE CHAMBERS
SUB-SECTION 9D
Figure 9D-15. Installing Push Rod
Figure 9D-13. Installing Piston Assembly
9. Connect a shop air supply to the spring chamber air inlet
4. Assemble the spring support and power spring onto the
and compress the power spring. Adjust the flange nut to
caging tool, and insert the tool through the piston assem-
provide a 1/16 to 1/8 inch (1.6 . 3.2 mm) gap at the piston
bly. Install the caging tool bushing and nut on the end of
neck. Secure the flange nut with the jam nut (see Figure
the tool. Tighten the nut slightly and center the power
9D-16).
spring over the piston hub and spring support.
10. Test the chamber for air leaks by applying air pressure
5. Tighten the caging tool nut until the holes in the spring
to both inlets. Maximum permissible leakage is 1 Ib./min.
support are aligned with the holes in the cylinder. Install
with a total volume of 200 cu. in./100 psi (3.278 cm3/6.89
the eight capscrews used to secure the spring support to the
BARS) test pressure.
cylinder. Alternately tighten each capscrew.
6. Remove the caging tool. Then install the push rod
bushing in the piston (see Figure 9D-14). Tap the bushing
lightly to be sure it is seated properly.
Figure 9D-16. Adjusting Flange Nut
INSTALLATION. Install a new or reconditioned Maxibrake
chamber as follows:
1. Position the chamber on the mounting bracket and run
on the stud nuts. Torque the nuts to 110 to 150 ft./lb.
Figure 9D-14. Installing Push Rod Bushing
(15.2-20.7 m-kg).
7. Assemble the spring retainer and push rod return spring
2. Connect a shop air supply to the spring chamber air
inlet and compress the power spring. Adjust the slack ad-
on the push rod, and install the assembly through the push
juster so it is perpendicular to the push rod when the push
rod bushing and piston tube. Install the flange nut on the
rod is at 50% of its stroke. Connect the push rod yoke to
end of the push rod (see Figure 9D-15).
the slack adjuster. Remove the air supply.
8. Install the diaphragm with the crown surface in the pres-
3. Connect all service air lines to the chamber, and com-
sure plate, and center the assembly over the cylinder. Apply
press the power spring. Check the clearance between the
pressure to the top of the pressure plate to squeeze the
flange nut and piston neck. The gap should be 1/16 to 1/8
diaphragm in place. Install the clamp band on the pressure
inch (1.6 - 3.2 mm). Adjust the gap if necessary and tighten
plate and cylinder. Be sure the service air inlet is in the
the jam nut.
position it was before the unit WaS disassembled. Tighten
4. Adjust the service brakes so that push rod travel is as
the clamp band bolts to 100 to 150 in./lb. (1.15 - 1.73
short as possible with no brake shoe drag.
m-kg).
9D-8
