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EATON Hydraulics
70160 Variable Displacement Piston Pump Repair Information E-PUPI-TS005-E June 2004
Model 70160
Disassembly
The following disassembly procedure applies to a single pump
with or without gear pump The
repair procedure for tandem
pumps, once they are separated, is
basically the same. The basic
configuration differences between
a single and tandem pumps are the
backplates, pump shafts and
housing assemblies. In most
cases, only the rear pump of
tandem units contain a charge pump, which is common to
both the front and rear pump. The rear tandem pump does not
incorporate a shaft seal.
Thoroughly clean the Eaton Model 70160 or 78162 variable
displacement pump before any
repairs are attempted. When
working on tandem pumps,
separate the front and rear pumps
first.
1
Support the pump with the
input shaft down. Use a 1/2 in.
socket or end wrench to remove
the pump adapter cover plate or
gear pump (see Figure 2).
2
Use a pick or similar tool to
remove the adapter cover plate or
gear pump o-ring. (See Figure 3)
3
Use a 7/16 in. Allen wrench or
bit socket remover to remove the
charge pressure relief valve spring
retainer from the pump adaptor
assembly (see Figure 4).
4
Use a pencil magnet or similar
tool to carefully remove the charge
pressure spring and poppet from
the pump adaptor assembly. (See
Figure 5) Use caution not to drop
the charge pump poppet into the
pump adaptor assembly.
5
The charge pressure relief
valve and poppet may be of the
standard or high pressure type. The
(6.9 to 10.3 bar [100 to 150 PSI])
standard spring and poppet are
shown on the bottom and the
optional high pressure (13.7 to
20.7 bar [200 to 300 PSI]) spring
and poppet is shown on the top.
The same charge pressure relief valve spring retainer is used
with either the standard or high
pressure (see Figure 6).
6
Use a 7/8 in. socket or end
wrench to remove the optional
bypass valve assembly from the
backplate (see Figure 7).
7
The internal seal may be
replaced by first removing the
small retaining ring on the end of
the bypass valve. Remove and
replace the o-rings (see Figure 8).
8
Use a 9/16 in. hex key to
remove the two high pressure relief
valves from the pumps backplate
assembly (see Figure 9). Remove
relief valve as shown from each
side (see Figure 10). Each system
relief valve S/A is identified by both
its part number and relief valve
setting as shown in Parts Information manual.
9
Firmly support the pump assembly. Use a 1/2 in. socket or
end wrench to remove the four cap screws retaining the charge
pump adapter assembly.
10
With the cap screws removed,
remove the charge pump adaptor
assembly from the backplate (see
Figure 11).
Note: The front pump assemblies
do not have charge pump adapter
assemblies.
11
Turn the adapter assembly
over. Use an o-ring pick or similar
tool remove the o-ring seal (see
Figure 12).
12
Inspect the gerotor pocket and
needle bearing located in the
charge pump adapter. The needles in the needle bearing must
remain intact in the bearing cage.
Repair Information
- Disassembly
Figure 1
Figure 2
Figure 3
Figure 5
Figure 4
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10
Figure 11
Figure 12
