Remove fittings from valve. Mark these fittings
Remove valve from chassis.
Suspended Pedal Valves
Remove nuts on exterior side of dash and
remove valve assembly.
Treadle Type Valves
Remove brake valve and treadle assembly by
removing three capscrews on outer bolt circle of
removed by removing three capscrews on inner
Installation of brake valve is basically the reverse of
removal. Be sure to make service checks before
returning vehicle to service.
Treadle Type Brake Valve (E6)
Refer to Fig. 8 for numbers in parenthesis.
If the entire brake valve and treadle assembly
was removed from the vehicle, remove the three
capscrews securing the treadle assembly to the
basic brake valve.
diaphragm (3) and washer (2) to exhaust cover
Remove four screws that secure exhaust cover
(4) to lower body (10).
Remove secondary inlet and exhaust valve
assembly (items 5 through 9) from lower body.
Disassembly of secondary inlet and exhaust
valve assembly is not required since it is only
serviced as an assembly.
Remove four hex head capscrews securing the
lower body (10) to upper body (11) and separate
Remove the rubber seal ring (12) from the lower
Apply thumb pressure to primary piston (16), lift
out and up on the three lock tabs of primary
piston retainer (19).
Using a 10 mm (3/8") wrench, hold ENSA nut on
threaded end of stem on top of primary piston.
Insert a screwdriver in exhaust passage through
center of valve and engage slotted head of the
Before proceeding with the disassembly
(refer to Fig. 8), note the ESNA nut and
stem are used to contain primary piston
return spring (17), stem spring (21) and
relay piston spring (14). Combined force
of these springs is approximately 222 N
(50 lbf) and care must be taken when
removing the ESNA nut as the spring
recommended that primary piston and
relay piston be manually or mechanically
contained while nut and stem are being
removed to prevent bodily injury.
Rotate the screwdriver counterclockwise and
remove stem (23), stem spring (21), spring guide
(22) and ESNA nut.
Remove relay piston (13), relay piston spring
(14), primary piston and primary piston return
spring from the upper body.
Disassemble primary piston by rotating the
spring seat nut (24) counterclockwise. Separate
spring seat nut, spring seat (20), rubber spring
(18) and remove piston O-ring.
Remove large and small O-rings from relay
Remove retaining ring securing primary inlet and
exhaust valve assembly (15) in upper body and
remove valve assembly. Do not disassemble
primary inlet as it is only serviced as an
CLEANING AND INSPECTION
Wash all metal parts in cleaning solvent and dry them.
Inspect all parts for excessive wear or deterioration.
Inspect valve seats for nicks or burrs. Check springs for
cracks or corrosion. Replace all rubber parts and any
part not found to be serviceable during inspection.
Treadle Type Brake Valve (E6)
Prior to reassembling brake valve, lubricate all O-rings,
O-ring grooves, piston bores and metal-to-metal moving
surfaces with Item 1 in LUBRICANT SPECIFICATIONS.
Refer to Fig. 8 for numbers in parenthesis. All torques
specified are assembly torques and can be expected to
differ after assembly is accomplished. Do not retorque
after initial assembly.
CTS-4079 CHAPTER IV - Page 7