JLG 450A II Series, Service And Maintenance Manual, Page: 84 / 396

SECTION 3 - CHASSIS & TURNTABLE
3-44 – JLG Lift – 3121290
Removal
Refer to Figure 3-40., Swing Motor Removal and Installation.
1. Thoroughly clean area around swing motor to prevent
dirt from entering system.
2. Tag and disconnect hydraulic lines to swing motor. Cap
or plug all openings.
3. Secure worm gear shaft so it does not pull out any when
removing swing motor. Failure to do so could damage
worm gear seals.
4. Remove bolts securing swing motor to swing drive
assembly.
5. Carefully pull the swing motor from the swing drive.
Preparation Before Disassembly
• Read this entire section before you disassemble motor or
any of its components for important information on parts
and procedures.
• Thoroughly clean off outside dirt, especially around fittings
and hose connections, before disconnecting and removing
motor. Remove rust or corrosion from coupling shaft.
• Remove coupling shaft connections and hose fittings and
immediately plug port holes and fluid lines.
• Remove motor, drain fluids, and take it to a clean work sur-
face.
• Clean and dry motor before disassembly.
• As you disassemble motor, clean all parts except seals in
clean petroleum-based solvent and blow them dry.
Table 3-11. Swing Motor Troubleshooting
Trouble Cause Remedy
Oil Leakage 1. Hose fittings loose, worn or damaged.
2. Oil seal rings (4) deteriorated by excess heat.
3. Special bolt (1, 1 A, 1B or 1C) loose or its sealing area deterio-
rated by corrosion.
4. Internal shaft seal (16) worn or damaged.
5. Worn coupling shaft (12) and internal seal (16).
Check & replace damaged fittings or “O” Rings.
Torque to manufacturers specifications.
Replace oil seal rings by disassembling unit.
(a) Loosen then tighten single bolt to torque spec-
ification.
(b) Replace bolt.
Replace seal. Disassembly of motor unit necessary.
Replace coupling shaft and seal by disassembling
unit.
Significant loss of speed under
load 1. Lack of sufficient oil supply
2. High internal motor leakage
3. Severely worn or damaged internal splines.
4. Excessive heat.
(a) Check for faulty relief valve and adjust or
replace as required.
(b) Check for and repair worn pump.
(c) Check for and use correct oil for temperature of
operation.
Replace worn rotor set by disassembling unit.
Replace rotor set, drive link and coupling shaft by
disassembling unit.
Locate excessive heat source (usually a restriction)
in the system and correct the condition.
Low mechanical efficiency or
undue high pressure required to
operate unit 1. Line blockage
2. Internal interference
3. Lack of pumping pressure
4. Excessive binding or loading in system external to motor unit.
Locate blockage source and repair or replace.
Disassemble unit, identify and remedy cause and
repair, replacing parts as necessary.
Check for and repair worn pump.
Locate source and eliminate cause.