11
IMPORTANT: To avoid unnecessary service, the pump should be tested prior to any service work. Please refer to Test
Procedures and Troubleshooting sections.
These service instructions only cover the basic pump portion of the entire pump assembly and are not all-inclusive. Certain
assumptions are made throughout the document, that the technician is capable of identifying worn parts and has the proper
equipment to perform the required repairs and tests.
For information regarding the rest of the pump assembly, please refer to the repair parts sheet for your specific unit.
2.0 DISASSEMBLY
2.1 Disassemble Hydraulic Pump Assembly
1. Be sure pump is disconnected from power source before
disassembling.
2. Remove pump from the cover plate.
3. Remove the intake filter by pulling on the end closest to the
pump. Be careful not to pull on the mesh screen or it may be
damaged.
4. If the pump is a 6-piston pump (note the number of flush
plugs in the piston ring) you will first need to remove the 6
screws (Fig. 2b, item 6) that are on the top of the pump with
a 5 mm Allen wrench.
5. Now remove the 12 screws (Fig. 5, item 5) on the bottom of
the pump using a 5 mm Allen wrench.
6. Pull up on the gear pump assembly (Fig. 1, item 4) to remove
it from the piston ring. Check the condition of the two
O-rings that are between the gear pump and the piston ring.
7. Remove the top ring (Fig. 3, item 4).
8. Pull up on the piston ring assembly (Fig. 1, item 3) to remove
it from the pump. Note: The hex cam may come off with the
assembly. This will hold the pistons in if you do not need to
service them
9. Remove the eccentric assembly (Fig. 1, item 2) from the
top plate. Check for signs of wear on the eccentric. If there
is material missing from the bearing areas the eccentric
assembly needs to be replaced. Also check the ID of the hex
cam for wear.
10. If present, remove locating washer (Fig. 3B, item 7).
2.2 Disassemble Piston Ring Assembly
(Refer to Figure 4.)
1. Remove the hex cam (Fig. 3, item 6) from the piston ring
assembly (Fig. 1, item 3). Note: Be careful, since the pistons
are spring loaded and they may come out abruptly.
2. Remove pistons (item 15) and spring (item 16).
3. Disassemble the bypass valve by removing the bypass end
cap (item 12) with a 13/16 inch [21 mm] wrench. Once the
bypass end cap is removed pull out the spring (item 11) and
piston (item 8).
Note:
If piston cannot be removed with fingers try using
pliers (use soft jaws so the piston does not get damaged).
4. Check to make sure that the back-up (item 9) and O-ring
(item 10) on the bypass piston (item 8) are both in good
condition.
5. Before the check valves are disassembled there are some
checks that should be done to determine if the check valves
are bad.
This is quick way to verify the integrity of your check valves.
The piston ring assembly (Fig. 1, item 3) should still have oil
on it from the disassembly. If the piston ring is dry you should
insert oil into the piston bores before putting the piston into
the bore. With the piston ring assembly (Fig. 1, item 3) in your
hands, install one piston (item 15) and spring (item 16) into a
piston bore. While covering the outlet O-ring (item 13) with your
thumb slowly push the piston (item 15) into the bore. Watch the
intake seat (item 3) to see if oil and air are bubbling out. If the
intake seat is good you will not notice anything coming out of
the intake seat (item 3) and you will have a high pressure trying
to push your thumb off of the outlet o-ring.
To check the outlet seat (item 6), cover up the inlet seat (item 3)
with your thumb. Slowly push the piston (item 15) into the piston
bore, the outlet seat (item 6) may spray oil so take care to point
it away from you. Once the piston is pushed all the way in let go
of the piston. Watch the outlet seat (item 6) to see if oil and air
are bubbling around the ball (item 4). If the outlet seat is working
correctly there should be no oil/air movement around the outlet
ball and the intake seat should create a strong vacuum on your
thumb.
This is the more detailed way to verify the integrity of your
check valves and should only be performed by an experienced
technician. These operations are time consuming and difficult
and should be performed only if absolutely necessary.
Remove all the pistons from the piston ring. Remove the
eccentric assembly from the top plate. Install the piston ring
onto the top plate with 12, M6x1.0x35, bolts (Enerpac P/N
CCA627028-1A). Torque the bolts to 120-144 in-lbs (13.5-16
Nm). If this is a 6 piston pump turn the pump over and reinstall
the 6 bolts (Fig. 2, item 6) into the top plate at 120-144 in-lbs
(13.5-16 Nm). Run a back pressure test up to 5,000 psi and
watch to see if any oil comes out of the piston bores. This
will show if you have any bad outlet checks that need to be
replaced.
The check for the inlet seats is complicated and should be
avoided. The eccentric assembly (Fig. 1, item 3) needs to be
installed in the top plate assembly (Fig. 1, item 1). All of the
pistons (item 15) need to be installed in the piston ring (item 1).
Install the piston ring assembly (Fig. 1, item 2) onto the top plate
with 12, M6x1.0x35, bolts (Enerpac P/N CCA627028-1A). Leave
the gear pump assembly (Fig. 1, item 4) off so that the intake
seats are visible. Torque the bolts to 120-144 in-lbs (13.5-16
Nm). If this is a 6 piston pump turn the pump over and reinstall
the 6 bolts (Fig. 2, item 6) into the top plate at 120-144 in-lbs
(13.5-16 Nm). The plug on the outside of the piston ring needs
to be removed with a 5/32nd [4 mm] Allen wrench. A 1/16th NPT
fitting needs to be installed in the port and hooked to a hand
pump, Enerpac P/N CK911032 can be used in conjunction with
a 10,000 psi hose. Turn the eccentric so that the piston that is
going to be tested is in the bore as deep as possible. The outlet
from the pump assembly needs to be plugged. Back pressure
into the port at 5000 psi and check to see if oil comes out of
the inlet check. This process needs to be repeated for all of the
pistons. When the testing is done for one of the ports the plug
needs to be reinstalled at 144-168 in-lbs [16.3-19 Nm].
If a check valve is damaged it can be replaced.
