Troubleshooting - JLG sky trak mmv Service Manual

Boom
4.5

TROUBLESHOOTING

This section provides an easy reference guide covering
the most common problems that occur during operation
of the boom.
Boom Troubleshooting
Problem
1. Boom will not extend or
retract.
2. Dropping chain, or jerky
boom extend or retract
functions.
4.46
Cause
1. Broken hydraulic hose(s) or
tube(s) and/or connections
leaking.
2. Extend/Retract hydraulic and/or
electrical system(s) not
operating properly.
3. Faulty Extend/Retract cylinder.
4. Broken chains or anchors.
1. Chain(s) tension not properly
adjusted.
2. Chain(s) stretched or binding.
3. Wear pads loose, contaminated,
excessively worn or damaged.
4. Contaminated, corroded or
rusted wear pad sliding
surfaces.
5. Extend/Retract hydraulic and/or
electrical system(s) not
operating properly.
6. Damaged boom section.
Remedy
1. Locate break, replace hose(s)
or tube(s), tighten connections.
2. Refer to Section 9.8, Hydraulic
Circuits and Troubleshooting
and/or Section 10.7.18, Boom
Extend/Retract Circuit and

Troubleshooting .

3. Repair cylinder. (Refer to Section
9.14.6, Extend/Retract Cylinder
4. Replace chains or anchors as
needed. (Refer to Section 4.3.6,
c. Chain Replacement .)
1. Adjust chain(s). (Refer to
Section 4.3.6, b. Extend Chain
Adjustment .)
2. Replace chain(s) as needed.
(Refer to Section 4.3.6, c. Chain
Replacement .)
3. Replace wear pads. (Refer to
Section 4.3.7, b. Boom Wear
Pad Replacement .)
4. Remove contamination and/or
corrosion from wear pad sliding
surfaces and lubricate. (Refer to
Section 4.3.7, c. Boom Wear
Pad Lubrication .) If the surfaces
cannot be reconditioned,
replace the boom section(s).
5. Refer to Section 9.8, Hydraulic
Circuits and Troubleshooting
and/or Section 10.7.18, Boom
Extend/Retract Circuit and
Troubleshooting .
6. Replace the damaged boom
section. (Refer to Section 4.3,
Boom Assembly Maintenance .)
Model MMV Rev. 12/04