Section VI - OVERHAUL
2. Check the wearing surfaces of the body, pressure
plate, ring and rotor for scoring and excessive wear.
Complete cartridges are available in service
Remove light score marks by lapping. Replace any heavily
kits for rebuilding these pumps. Refer to the
scored or badly worn parts.
catalogs listed in Table I for part numbers.
3. Inspect the vanes for burrs, wear and excessive
play in the rotor slots. Replace the rotor if the slots are
Plug all removed units and cap all lines to prevent the
entry of dirt into the system. During disassembly, pay
4. Check the bearings for wear and looseness.
particular attention to identification of the parts, especially
Rotate the bearings while applying pressure to check for
the cartridges, for correct assembly. Pump bearings are
pitted or cracked races.
pressed in the bodies or on the shafts and should not be
5. Inspect the oil seal mating surface on the shaft for
removed unless defective. Figure 7 is an exploded view
scoring or wear. If marks on the shaft cannot be removed
which shows the proper relationship of the parts for
by light polishing, replace the shaft.
disassembly and assembly. Figure 1 can be referred to for
6. Check the relief valve sub-assembly for free
the correct assembled relationship of the parts.
movement in the cover bore. Remove burrs from the
valve by polishing, but do not round off the corners of the
lands. Do not attempt to rework the valve bore. If the
1. Disassembly of basic pump - See Figure 7. If a
bore is damaged, replace the cover.
mounting flange or foot bracket is used, remove it before
dismantling the pump. Clamp the pump body in a vise (not
too tightly), cover end up, and remove the four cover
Coat all parts with hydraulic fluid to facilitate assembly
screws. Note the position of the cover port with respect to
and provide initial lubrication. Use small amounts of
the body port before lifting off the cover and "O" ring. (See
petroleum jelly to hold "O" rings in place during assembly.
paragraph 2 for disassembly of flow control covers.)
Remove the pressure plate and spring and note the
position of the ring for correct reassembly. Lift off the ring
During handling and shipping of the precision
and remove the locating pin. Separate the vanes from the
machined cartridge parts, it is possible to
rotor and remove the rotor from the shaft.
raise burrs on the sharp edges. All sharp
Turn the pump body over and remove the shaft key
edges on the parts of a new cartridge kit
and the snap ring which retains the outer bearing. Tap with
should be stoned prior to installation.
a soft hammer on the splined end of the shaft to force the
shaft out of the body. Support the bearing inner race and
1. Assembly of Flow Control Cover - See Figure 7. If
press the shaft out of the bearing. Pull the shaft seal out
the cover has a through bore, insert the valve in the bore,
of the body with a suitable hooked tool and press out the
small land first. Then install the spring and pipe plug. For
models with the blind bore, first install the spring, then the
2. Disassembly of Flow Control and Relief Valve
valve, with the hexagon head end first. Follow this with the
Covers - See Figure 7. If a screen is used in the cover,
snap ring (being certain it is firmly seated in the groove)
remove the plug and pull out the screen. Do not remove
and the pipe plug. Install the screen and the plug which
the orifice plug unless it is necessary. Check whether there
is a plug at each end of the relief valve bore. If the bore
2. Assembly of Pump - See Figure 7. Begin assembly
is blind, remove the plug and the snap ring to release the
by pressing the shaft into the front bearing while supporting
valve and spring as shown in the inset view, Figure 7. If
the bearing inner race. Next, press the inner bearing into
the bore is through the cover, remove only the one plug to
the body, using a driver which contacts the outer race only.
release the spring and valve. Leave the snap ring and the
Be certain both bearings are firmly seated.
other plug in the cover.
C. INSPECTION AND REPAIR
Before assembling the shaft seal, determine
1. Discard the used shaft seal and all "O" rings.
the correct position of the sealing lip. (See
Wash the metal parts in mineral oil solvent, blow them dry
Figure 8.) Double lip seals are assembled with
with filtered compressed air and place them on a clean
the spring toward the pumping cartridge.
surface for inspection.
Single lip seals have two pressure holes, which
are assembled toward the shaft end of the