Service Manual Instruction Manual

SECTION 2 - GENERAL
2-4 – JLG Lift – 3121616
2.3 LUBRICATION AND INFORMATION
Hydraulic System
1. The primary enemy of a hydraulic system is contamina-
tion. Contaminants can enter the system by using inade-
quate hydraulic oil; allowing moisture, grease, filings, or
other contaminants to enter during maintenance; or
allowing the pump to cavitate due to insufficient system
warm-up or leaks in pump supply (suction) lines.
2. Design and manufacturing tolerances of component
working parts are very close. The smallest amount of dirt
or other contamination entering a system can cause
wear or damage to components and faulty operation.
Take every precaution to keep hydraulic oil clean -
including reserve oil in storage. Check, clean, and
replace hydraulic system filters as at intervals specified
in the Lubrication Chart in Section 1. Always examine fil-
ters for metal particles.
3. Cloudy oils indicate high moisture content which per-
mits organic growth and causes oxidation or corrosion.
If this condition occurs, the system must be drained,
flushed, and refilled with clean oil.
4. It is not advisable to mix oils of different brands or types.
They may not contain required additives or be of com-
parable viscosities. Good grade mineral oils, with viscos-
ities suited to ambient temperatures in which the
machine is operating, are recommended for use.
NOTE: Metal particles may appear in oil or filters of new machines
due to wear-in of meshing components.
Hydraulic Oil
1. Refer to Section 1 for viscosity ranges.
Changing Hydraulic Oil
1. Filter elements must be changed after first 50 hours of
operation and every 300 hours (unless specified other-
wise) thereafter. If it is necessary to change the oil, use
only oils meeting or exceeding specifications in this
manual. If unable to obtain same type of oil supplied
with the machine, consult local supplier for assistance in
selecting the proper equivalent. Do not mix petroleum
and synthetic base oils.
2. Keep hydraulic oil clean. If oil must be poured from orig-
inal container into another, clean all possible contami-
nants from service container. Always clean filter mesh
element and replace cartridge any time oil is changed.
3. Inspect all hydraulic components, lines, fittings, etc.
while unit is shut down. Perform a functional check of
each system before placing machine back in service.
Lubrication Specifications
Specified lubricants, as recommended by component manu-
facturers, are always the best choice. However, multi-purpose
greases usually have qualities which meet a variety of single
purpose grease requirements. Should questions arise regard-
ing use of greases in maintenance stock, consult your local
supplier for evaluation. Refer to Section 1 for an explanation of
lubricant key designations in the Lubrication Chart.
2.4 CYLINDER DRIFT TEST
Measure maximum acceptable cylinder drift using the follow-
ing methods.
Platform Drift
Measure platform drift to ground. Lower booms (if equipped)
slightly elevated, main boom fully extended with rated load in
platform and power off. Maximum allowable drift is 2 inches (5
cm) in 10 minutes. If machine does not pass this test, proceed
with the following.
Cylinder Drift
Measure drift at cylinder rod with a calibrated dial indicator.
Cylinder oil must be at stabilized ambient temperature.
Cylinder must have normal platform load applied.
Cylinder is acceptable if it passes this test.
Table 2-2. Cylinder Drift
Cylinder Bore Diameter
Max. Acceptable Drift
in 10 Minutes*
inches mm inches mm
3 76.2 0.026 0.66
3.5 89 0.019 0.48
4 101.6 0.015 0.38
5 127 0.009 0.22
6 152.4 0.006 0.15
7 177.8 0.005 0.13
8 203.2 0.0038 0.10
9 228.6 0.0030 0.08
*Based on 6 drops per minute cylinder leakage.