12
Check Valve Removal
1. Set piston ring assembly in a bench press with the o-ring
grooves on the bottom. Make sure that there is clearance
in the bench vice support for the check valve to be pushed
out.
2. Insert a punch that is 5/32nd (4 mm) or smaller into the
intake hole. The punch should go through the intake seat
and rest on the check ball. Push on the punch with a
maximum of 2000 lbs [907 kg]. This will push the outlet
check assembly out in one piece and will push out the ball
and spring for the inlet check valve.
3. Instead of removing the intake seats the damaged seats
can be reworked using methods such as a ball hone.
4. Remove the inlet seat (Fig. 4, item 3) by using a 11/64" flat
bottom punch. This operation can damage the piston ring
if the punch is not the correct diameter. Place the punch
on the inlet seat and apply a maximum of 2000 lbs [907 kg]
with a bench press to drive the punch down.
Note:
With this procedure both seats will likely be damaged and
will need to be replaced.
2.3 Disassemble Gear Pump
Note:
Only disassemble the gear pump as a last resort, after all
other options have been tried. Contamination and damage to
the internal parts of the gear pump can cause the pump to fail.
Parts are not sold separately for the gear pump. If the pump is
damaged, the complete assembly has to be changed.
1. Remove the 5 hex screws with a 1/2 inch [13 mm] socket.
It is recommended that the gear pump be taken apart while
the rest of the pump is assembled so there is a way to
secure it.
2. Remove the end plate from the gear pump. Check for signs
of wear or contamination.
3. The gears can be removed from the gear pump to check for
wear but note the orientation of the gears for re-assembly.
3.0 ASSEMBLY
3.1 Assemble Gear Pump
1. Insert drive gear and driver gear into gear pump assembly,
make sure tang drive is protruding in the middle of the
bearing.
2. Position the top gear pump housing and secure with 5 hex
cap screws at 13 ft-lbs. Tighten in an alternating sequence.
3. Install oil in the O-ring grooves on the bottom of the gear
pump to help hold the O-rings in place. Place the two
O-rings (Fig. 5, item 3, 4) into the grooves.
3.2 Assemble Piston Ring Assembly
1. Insert inlet seat (Fig. 4, item 3) into piston ring assembly (Fig.
4, item 1) by using tool DC9505816 and a hydraulic press.
Use a maximum force of 1500 pounds—
WARNING: if this
force is exceeded the piston ring will be damaged.
2. Place check ball (Fig. 4, item 4) onto inlet seat (Fig. 4, item
3) and apply a maximum of 1500 lbs. of force by using tool
DC9505816 and a hydraulic press to coin the seat.
3. Next insert spring (Fig. 4, item 5) on top of ball (Fig. 4, item
4). Make sure the small end of the spring rests on the ball.
(See Fig. 4.)
4. Place upper check valve (Fig. 4, item 6) into piston ring (Fig.
4, item 1).
5. Place check ball (Fig. 4, item 4) on outlet seat (Fig. 4, item 6)
and apply 1500 lbs. of force by using tool DC9505816 and
a hydraulic press. Note: This will install and coin the outlet
seat in one operation.
6. Place spring (Fig. 4, item 5) on outlet check ball (Fig. 4, item
4). Make sure the small end of the spring rests on the ball.
(See Fig. 4). Repeat this 2, 3 or 6 times as required.
7. The retaining ring (Fig. 4, Item 7) is slightly convex and
should be installed with the concave side on top. Carefully
compress the spring with the retaining ring making sure to
keep the spring in the upper check. Press the retaining ring
in with the retaining ring tool. The retaining ring tool will
set the depth of the retaining ring. If the retaining ring is
installed too deep or at angle it may need to be lightly pried
out to make it even. When installed properly the retaining
ring should rotate in the outlet check.
8. Place back-up washer (Fig. 4, item 9) onto the by-pass
piston (Fig. 4, item 8). Next install the O-ring (Fig. 4, item
10) onto the bypass piston. This order is critical to the
operation of the bypass, see Figure 4 for reference. Make
sure the back-up washer is tightly wrapped around the
piston so that it does not get damaged when installing it in
the piston ring.
9. Lube the o-ring and backup, then carefully insert by-pass
piston (Fig. 4, item 8) with back-up washer and O-ring into
by-pass hole in piston ring assembly. Place spring (Fig. 4,
item 11) over the by-pass piston. Next thread by-pass end
cap (Fig. 4, item 12) into the piston ring. Install by-pass end
cap to the depth specified in the Test Specification Table (see
page 11).
10. Insert piston (Fig. 4, item 15) assembly into narrow end of
piston spring (Fig. 4, item 16).
11. Insert piston (Fig. 4, item 15) and spring into piston ring
(Fig. 4, item 1). Repeat this 2, 3 or 6 times as required.
12. Install O-rings (Fig. 4, item 13) into piston ring outlet holes.
Repeat this 3, 4 or 7 times as required.
13. Place small O-ring (Fig. 4, item 14) into by-pass pilot hole.
14. Place two nylon balls (Fig. 4, item 17) into piston ring
assembly.
3.3 Assemble Hydraulic Pump Assembly
1. Place fully assembled top plate assembly on table with
shaft seal on the bottom.
2. If used, place locating washer (Fig 3B, item 7) into recessed
area of top plate (Fig. 1, item 1). Align center hole with bore.
IMPORTANT:
Locating Washer (Fig. 3B, item 7) must be installed on:
• ZE, ZG and ZW pump elements with date code D.
• ZE, ZG and ZW Series pump elements (date code
A, B or C) that are being updated from the original
aluminum top plate to the new steel top plate.
DO NOT install Locating Washer (Fig. 3B, item 7) on:
• ZA Series pump elements (all date codes).
•
ZE, ZG and ZW Series pump elements (date code A,
B or C) with the original aluminum top plate that are
NOT being updated to the new steel top plate.
3. Carefully insert eccentric (Fig. 3, item 1) into the top plate
(Fig. 1, item 1). On direct drive units place oil on eccentric
shaft to ease insertion through shaft seal.
