JLG 680S, Service And Maintenance Manual

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SECTION 5 - BASIC HYDRAULICS INFORMATION & SCHEMATICS
3121234 5-57
5.6 PISTON PUMP (SN 0300180778 THROUGH
0300189341)
Servo Controlled Piston Pump
DISASSEMBLY
The following instructions apply to a single servo controlled
piston pump with or without a gerotor charge pump. A tan-
dem 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 capscrews
up. Mark the relationship of the working ports (for
assembly identification) to the servo control assembly
with a scribe. Remove the four capscrews retaining end-
cover.
2. Lift the charge pump adapter assembly straight up off
endcover, shaft and gerotor. Gerotor may stay in adapter
or on endcover.
3. Remove o-ring from charge pump adapter.
4. Remove outer gerotor ring from either the charge pump
adapter or the inner gerotor ring.
NOTE: Refer to “Charge Pump Adapter Assembly” for disassembly
and inspection of charge pump adapter assembly.
5. Remove the inner gerotor ring and key from drive shaft
or inner gerotor ring and coupler assembly from shaft.
6. Lift endcover straight up off shaft and housing. Remove
valve plate from endcover or from rotating kit assembly,
still in housing.
7. From endcover, remove bypass valve or plug, and relief
valve assemblies. Note: Mark the relief valve in relation-
ship to the cavity it was removed, for reassembly pur-
poses.
Endcover Inspection
• Check the bearing (press fit) in endcover. If needles remain
in cage, move freely, and setting is at the dimension shown
in Figure 5-90., removal not required.
• Check roll pin in endcover. If tight and set to the dimension
shown in Figure 5-90., removal not required.
1. Remove housing gasket from housing or endcover.
2. With pump still in vise, remove the six capscrews retain-
ing the manual servo control assembly. Remove the
control assembly and control housing gasket from the
housing. Remove orifice plates, noting location for reas-
sembly. Remove nut and lock washer from control arm,
remove arm. Note position of control arm for reassem-
bly.
NOTE: Refer to “Manual Servo Control Basic Assembly” for disas-
sembly and Inspection of control assembly.
3. To remove rotating kit assembly from housing, first
remove pump from vise holding the rotating kit assem-
bly in position. Lower pump so that the shaft end (flange
end) is up. Set the rear of housing onto table with hous-
ing flat and rotating kit assembly at rest on table. (Hole
in table, for protruding shaft, is required.) Lift and
remove the housing and shaft from rotating kit assem-
bly, and swashplate.
4. Remove swash plate from rotating kit assembly and
servo piston follower from swashplate.
NOTE: Refer to “Rotating Kit Assembly” for disassembly and
Inspection of rotating kit.
Numbered End
2.29 mm
(0.09 in.)
4.39 mm
(0.173 in.)
Figure 5-90. Endcover Inspection