JLG 450A_AJ Series II Service Manual - Manual (Page 328)

SECTION 5 - HYDRAULICS
5-38 – JLG Lift – 3121180
Charge Pump
Disassemble charge pump to inspect and clean, or
change auxiliary shaft drive coupling.
1. Remove auxiliary pump, if necessary.
2. Remove screws retaining charge pump cover to
pump housing (Torx T). Seven screws are used with
“no pad” or SAE “A” auxiliary mounting pad charge
pump cover, and six screws are used with SAE “B”
auxiliary mounting pad charge pump cover. Remove
charge pump cover, gasket, and cover locating pins.
3. Remove gerotor cover assembly from charge pump
cover or back of pump housing. Remove gerotor
cover O-rings. Two O-rings are used on gerotor
cover of all pumps. (An additional O-ring was used
on gerotor cover of very early production pumps
with SAE “A” pad option.)
4. Remove gerotor assembly from gerotor cover or
pump housing.
5. Remove gerotor drive pin and drive coupling. Remove
gerotor cover locating pin from pump housing.
6. Inspect each part separately if they are to be reused.
If either gerotor assembly parts needs to be replaced,
they must both be replaced. Always replace O-rings
and charge pump cover gasket. Inspect journal bear-
ing in gerotor cover for excessive wear.
7. Lubricate gerotor assembly with clean hydraulic oil
before assembly.
8. Install gerotor drive pin into hole in drive coupling.
Apply grease or petroleum jelly to keep in place.
9. Install drive coupling onto pump shaft with smaller
outside diameter facing away from pump shaft. Dif-
ferent couplings are used with different auxiliary pad
options.
10. Install gerotor assembly onto coupling.
11. Install gerotor cover locating pin into pump housing.
Install gerotor cover assembly over gerotor. Locating
pin must engage slot in gerotor cover.
NOTE: Charge pump rotation is determined by location of
gerotor recess and pressure balance hole in gerotor
cover. Different gerotor covers are used for clock-
wise and counterclockwise rotation pumps.
12. Install new pressure balance O-rings onto gerotor
cover and retain with petroleum jelly or grease. (An
additional O-ring was used on gerotor cover of very
early production pumps with SAE ”A” pad option.)
13. Install charge pump cover locating pins and new
charge pump cover gasket.
14. Install charge pump cover. Cover must engage gero-
tor cover and locating pins. Install charge pump cover
screws. Torque evenly to 26 - 32 ft-lb (36-43 Nm).
15. Reinstall auxiliary pump if necessary.