SUB-SECTION 9D
BRAKE CHAMBERS
LEAKAGE TEST. The Maxibrake system should be
3. Make a full service brake application by depressing and
checked periodically to determine that the brakes are suit-
holding the treadle valve. Check the air gauge for a drop in
able for continued service or to determine whether a prob-
pressure. An air pressure drop of over 3 pounds per minute
lem is caused by a faulty Maxibrake chamber. Test the
indicates that excessive leakage beyond the treadle valve
system as follows:
exists.
4. If leaks occur at the points indicated above, they should
1. Start the engine and build-up maximum air pressure.
be repaired before the machine is returned to service.
Stop the engine and depress the Maxibrake control valve
knob. Then check the air gauge for a drop in pressure. A
DISASSEMBLY. To disassemble a Maxibrake chamber, pro-
drop in pressure indicates that a leek exists in the air supply
ceed as follows. Refer to Figure 9D-5, unless otherwise di-
system.
rected.
NOTE
2. Pull the Maxibrake control valve knob outward from the
dash panel, and check the air gauge for a drop in pressure
To ensure that the Maxibrake chamber is serviced
after the Maxibrakes are released. A drop in pressure indi-
quickly and safely, it is recommended that the caging
cates that a leak exists beyond the control valve.
tool and servicing bracket shown in Figure 9D-4 be
used. These tools can be manufactured locally or pur-
chased from the chamber manufacturer at the address
Coat the pressure plate, clamp ring, and push rod of the
shown on Figure 9D-4.
Maxibrake chamber with a soap solution to determine if the
leakage is within the chamber itself. Maximum permissible
1. Mount the Maxibrake chamber on the servicing bracket
leakage at these points is 1 Ib./min. with a total volume of
and secure it with the stud nuts (see Figure 9D-6).
200 cu. in/100 psi (3.227 m3/6.89 BARS) test pressure.
Figure 9D-5. Exploded View - Maxibrake Chamber
9D-5
