DEMO - 1965 Ford Truck Shop Manual - ForelPublishing.com

2-34 GROUP 2 - BRAKES
the release bolt nut bottoms (approximately
18 turns).
3. To avoid possible injury, be
sure that the actuating spring is
mechanically compressed before
removing the clamp ring. Remove
the clamp bolt, expand the clamp
ring, and slide it off the Fail-Safe
and non-pressure housings.
4. Remove the Fail-Safe unit from
the non-pressure housing.
INSTALLATION
1. If the diaphragm is worn or
damaged, replace it. Check the
wedge assembly to be sure that the
parts have not been disengaged during
disassembly. Be sure that the
wedge rod fits into the socket of the
diaphragm plate and push rod assembly
(Fig. 8).
2. Install the diaphragm against
the plate and push rod assembly,
and mount the Fail-Safe unit against
the diaphragm and non-pressure
housing. Secure the Fail-Safe unit to
the non-pressure housing with the
clamp ring. Tighten the clamp ring
bolt and nut, then install the warning
tag.
3. Turn the release bolt counterclockwise
(approximately 18 turns)
to release the manual compression
of the actuating spring.
4. Start the engine and compressor
to build up system pressure for air
compression of the spring.
MAJOR REPAIR OPERATIONS
MAXIBRAKE
DISASSEMBLY
Before disassembling the brake
chamber, mark both the pressure
plate and cylinder assembly with
relation to the clamping ring and
the air line fittings, so that the unit
can be reassembled in the same
position. This will eliminate the possibility
of installation interference
and assure correct positioning of
the air line fittings.
1. Remove the clevis yoke and
the flanged nut from the push rod
and install a Z A inch OD x s /a inch
ID flat washer and a s /s NF nut on
the push rod—tighten the nut until
the plate end of the push rod is
seated on the safety piston spring
SERVICE BRAKE
AIR INLET
SAFETY
PISTON
O-RING
SEALS
SERVICE \ PUSH ROD
PISTON SAFETY PISTON SEAL
AND SPRING SEAT
PUSH ROD
ASSEMBLY
RING
FIG. 9-Maxibrake-Sectional View
support. It is necessary to compress
the push rod return spring and the
safety piston spring, so the unit may
be disassembled safely without spring
pressure on the safety piston spring
support, and the diaphragm and
pressure plate assembly (Fig. 9).
2. Remove the clamp ring, pressure
plate, and the service diaphragm
from the cylinder assembly.
3. Remove the eight cap screws
that secure the safety piston spring
support to the cylinder body and remove
the complete inner assembly.
4. Set the push rod and piston
assembly on a work bench and unthread
and remove the nut and
washer used to compress the springs.
With the spring tension removed,
disassemble the push rod, return
SAFETY
PISTON
J
SAFETY CHAMBER
AIR INLET
MOUNTING
STUD
CHAMBER
H1255-A
spring, safety piston, safety piston
spring, and the spring seat.
5. Remove the push rod seal
from the bore of the piston and remove
the O-ring seals from the piston
and the cylinder.
ASSEMBLY
Always be sure that the correct
return spring is used in any brake
chamber. Also be sure that the brake
chamber on the opposite side of the
axle has the same return spring;
otherwise uneven braking will result
If a new diaphragm is installed in
the brake chamber on one side of the
axle, a new one should be installed in
the corresponding brake chamber on
the opposite side also; otherwise uneven
braking may result.
1. Coat the safety piston and the
inside of the cylinder assembly with
a light coat of Lubriplate or other
suitable lubricant.
2. Rest the push rod upright on a
flat surface and assemble in order—
the push rod return spring, safety piston
spring seat and spring, and the
safety piston. Compress the push rod
and safety piston springs by installing
the nut and flat washer used in
the disassembly procedure.
3. Install the push rod seal in the
piston bore and install the O-ring
seals on the piston and in the cylinder
assembly.
4. Position the piston and spring
assembly into the cylinder assembly.
Align the threaded holes in the safety
piston spring support with the holes
in the side of the cylinder, and install
the retaining cap screws.
5. Position the diaphragm and
pressure plate with the clamp ring
to the cylinder assembly, align the
marks made prior to disassembly and
tighten the clamp ring.