TRUCK SERVICE MANUAL
BRAKES-AIR
SERVICE CHECKS
DISASSEMBLE
Operation Test
Remove the four capscrews that hold the valve cover
to the body. Separate cover, gasket and body. Push
With two test gauges you know to be accurate,
piston assembly out of body. If necessary, the piston
disconnect one of the front brake chamber lines or
assembly can be dismantled and its component parts
remove the plug from the unused brake chamber inlet
serviced. To disassemble the piston assembly, first
port, if this type, and install one of the test gauges. The
remove the piston grommets.
other test gauge should be installed in a foot brake valve
delivery line. Place the handle of the two-way valve in
The boot type inlet and exhaust valves are
the dry road position and make a foot valve application.
removable and serviceable. They can either be cut or
Readings on both test gauges should be the same.
pryed off the stem.
Release the foot application and note that the air is
exhausted promptly at the exhaust port of the limiting
Remove the exhaust valve, valve guide and spring.
and quick release valve.
Pull the valve stem through the piston and remove
Place the handle of the two-way valve in the slippery
the inlet valve from its stem.
road position and apply the foot valve. The reading on
CLEANING AND INSPECTION
the test gauge connected in the brake chamber or line
should be about one-half the reading on the test gauge
Clean all metal parts of both valves in good cleaning
connected to the brake valve delivery line.
solvent and dry thoroughly. All rubber parts will be
replaced. Check all metal seats for scratches or scores.
Leakage Test
Polish seats with fine crocus cloth when they are nicked
With the two-way valve handle in the dry road
or corroded. Inspect all springs for cracks, distortion and
position, make and hold a foot valve application. Check
corrosion and replace where necessary.
the exhausts of both the two-way and limiting and quick
release valves for leakage.
REASSEMBLE
If an arbor press is available, the inlet and exhaust
Place the handle of the two-way valve in the slippery
valve boots should be pressed on the stem dry. Without
road position. Make a foot valve application and check
an arbor press a little soap or water will make it easier to
the exhaust of the two-way valve for leakage.
press on the stem.
If the limiting and quick release valve or two-way
Install inlet valve boot on stem and insert in piston.
valve does not function as noted above or if leakage is
excessive, it is recommended that they be reconditioned
Position spring and valve guide over stem and press
or replaced.
exhaust valve boot on stem.
REMOVE AND REINSTALL.
Lubricate body and cover bores, grommet and
grommet grooves and other areas of the piston with a
Remove
lubricant comparable to that listed in "LUBRICATION
SPECIFICATIONS" item 1.
To remove the limiting and quick release valve
assembly, disconnect all air lines at valve and remove
Press piston assembly in body but with caution so
mounting bolts.
piston grommets are not damaged.
Install
Position gasket and cover on body and install four
capscrews with lock washers.
Install valve in same location where removed using
same mounting bolts. Connect brake chamber lines to
delivery ports of valve and brake valve delivery line to top
of inlet port and line from two-way valve to side inlet port.
The perform the tests listed in "SERVICE CHECKS".
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