Tennant 7400, Service Manual

Page: 224 / 322

8 8
Model 70142 / 70144 and 70145
Disassembly
8 Remove housing gasket from housing or backplate.
9 To remove rotating kit assembly from housing, first
remove pump from vise holding the rotating kit assembly in
position. Lower pump so that the shaft end (flange end) is up.
Set the rear of housing onto table with housing flat and rotating
kit assembly at rest on table. Hole in table for protruding shaft
is required. Remove by lifting the housing and shaft from
rotating kit assembly.
Refer to Appendix B for disassembly and Inspection of rotating
kit.
10 Remove retaining ring from the front of housing. Press the
shaft, shaft seal or spacer, and washer from housing. Remove
retaining ring, thrust washer, thrust bearing, second thrust
washer, and second retaining ring from shaft.
11 To remove camplate from housing, remove the two screws
from both sides of housing (four total) retaining seal cover and
trunnion cover. Remove seal cover, shaft seal, washer, and
bearing from housing. Remove trunnion cover, o-ring cover, o-
ring, washer, inner race, and bearing from housing. Slide the
camplate over to one side and remove thru the back side of
housing.
Camplate Inspection:
• The finish on the piston shoe surfaces of the camplate
should show no signs of scoring.
Housing Inspection:
• Check the bearing (press fit) in front of housing. If
needles remain in cage, move freely, and setting at the
dimension shown in figure 1-4, removal not required.
1.78 mm
[.07 in.]
Numbered End
Flange End of Housing
Figure 1-4
12 Discard the shaft seal, gaskets, and o-rings from all
assemblies. Replace with new seals upon reassembly.
Disassembly
The following instructions apply to a variable displacement
piston pump with or without a gerotor charge pump. A tandem
pump assembly should be separated into individual pumps
before disassembly.
1 Position the pump into a protected jaw vise, clamping onto
the outer portion of the flange, with the input drive shaft down.
Remove the four cap screws retaining charge pump adapter or
backplate.
No gerotor charge pump skip to step 6.
2 Lift the charge pump adapter assembly straight up off
backplate, shaft, and gerotor. Gerotor may stay in adapter or on
backplate.
3 Remove o-ring from charge pump adapter.
4 Remove outer gerotor ring from either the charge pump
adapter or the inner gerotor ring.
Refer to Appendix A for disassembly and inspection of charge
pump adapter assembly.
5 Remove the inner gerotor ring and coupler assembly from
shaft.
6 Lift backplate straight up off of shaft and housing. Remove
valve plate from backplate or from rotating kit assembly, still in
housing.
7 From backplate remove dump valve assembly or plug
assembly, and relief valve assemblies. Note: Mark the relief
valve in relationship to the cavity it was removed, for
reassembly purposes.
Backplate Inspection:
• Check the bearing (press fit) in backplate. If needles
remain in cage, move freely, and setting is at the dimension
shown in figure 1-3, removal not required.
• Check roll pin in backplate. If tight and set to the
dimension shown in figure 1-3, removal not required.
2.79 mm
[.110 in.]
1.91 mm
[.075 in.]
Numbered End
Figure 1-3