JLG G5-18A Service Manual page 148

Hydraulic System
1
6. Label, disconnect and cap all hydraulic hoses
attached to the pump, cap all fittings and plug hoses
to keep dirt & debris from entering the hydraulic
system.
7. Remove the two bolts that hold the pump in place.
b. Implement Pump Disassembly
1. Mark the position of the body and flange to ensure
correct reassembly
2. Remove the nuts and washers attaching the flange
to the body. If necessary, carefully separate with a
soft faced hammer.
3. Remove the retaining circlip and shaft seal from the
flange.
4. Pull out the main shaft assembly. Mark the position
of the drive gear and balance plate. Remove the
drive gear and balance plate.
5. Discard all seals and clean off all sealant from the
flange/body interface.
c. Implement Pump Cleaning
Clean all pump components with a suitable cleaner such
as trichlorethylene.
8-12
d. Implement Pump Inspection
Inspect internal pump components for wear, damage,
etc. If inner surfaces of the pump DO NOT display an
ultra-smooth, polished finish, or are damaged in any way,
replace the damaged part. Often, dirty hydraulic fluid
causes failure of internal pump seals and damage to the
polished surfaces within the pump and other hydraulic
system components.
Inspect the o-ring groove and shaft seal recess in the
mounting flange. Be sure they are undamaged and free
from burrs.
The pump must be replaced if:
1. The PFE coated bearings in the body and flange are
worn through revealing the bronze backing.
2. The gear side faces are scored.
MY2100
3. There is a noticeable wear groove on the main shaft
where the shaft seal lips run.
4. The bronze balance plates are scored.
Note: It is not recommended that damaged gears/
bodies, flanges or balance plates are replaced
individually as this will not constitute a good repair.
Note: ALWAYS replace seals, o-rings, gaskets, etc.,
with new parts to help ensure proper sealing and
operation. Lubricate seals and o-rings with clean
hydraulic oil.
e. Implement Pump Assembly
Note: Before assembly, all parts must be perfectly clean
and lubricated with hydraulic fluid. Renew all seals using
hydraulic fluid as a lubricant.
1. Fit the shaft seal mounting flange with the garter
spring facings into the pump and refit the circlip.
2. Fit the channel seals and back-up rings into grooves
on balance plate into bore. Ensure that the seals
remain in their groove and that the two small holes in
the balance plate are to the low pressure side of the
pump.
3. Insert the main shaft and drive gear into their original
bores.
4. Replace the second balance plate into its original
position. Be sure the small holes are to the low
pressure side, fit the channel seal and back-up ring.
5. Fit the o-ring into its groove in the mounting flange
and apply a small amount of Loctite
front face of the body.
®
to the lower
G5-18A, 2505