JLG M4069 Service Manual - Manual (Page 73)

SECTION 4 - HYDRAULICS
3121824 – JLG Lift – 4-1
SECTION 4. HYDRAULICS
4.1 SERVICING AND MAINTENANCE
GUIDELINES
General
The following information is provided to assist you in the
use and application of servicing and maintenance proce-
dures contained in this chapter.
Safety and Workmanship
Your safety and that of others is the first consideration
when engaging in the maintenance of equipment. Always
be conscious of weight. Never attempt to move heavy
parts without the aid of a mechanical device. Do not allow
heavy objects to rest in an unstable position. When raising
a portion of the equipment, ensure that adequate support
is provided.
Cleanliness
1. The most important single item in preserving the
long service life of a machine is to keep dirt and for-
eign materials out of the vital components. Precau-
tions have been taken to safeguard against this.
Shields, covers, seals and filters are provided to
keep oil supplies clean; however, these items must
be maintained on a scheduled basis in order to func-
tion properly.
2. At any time when hydraulic oil lines are discon-
nected, clear adjacent areas as well as the openings
and fittings themselves. As soon as a line or compo-
nent is disconnected, cap or cover all openings to
prevent entry of foreign matter.
3. Clean and inspect all parts during servicing or main-
tenance, and assure that all passages and openings
are unobstructed. Cover all parts to keep them
clean. Be sure all parts are clean before they are
installed. New parts should remain in their contain-
ers until they are ready to be used.
Component Removal and Installation
1. Use adjustable lifting devices, whenever possible, if
mechanical assistance is required. All slings (chains,
cables, etc.) should be parallel to each other and as
near perpendicular as possible to top of part being
lifted.
2. Should it be necessary to remove a component on
an angle, keep in mind that the capacity of an eye-
bolt or similar bracket lessens, as the angle between
the supporting structure and the component
becomes less than 90°.
3. If a part resists removal, check to see whether all
nuts, bolts, cables, brackets, wiring, etc. have been
removed and that no adjacent parts are interfering.
Component Disassembly and Reassembly
When disassembling or reassembling a component, com-
plete the procedural steps in sequence. Do not partially
disassemble or assemble one part, then start on another.
Always recheck your work to assure that nothing has been
overlooked. Do not make any adjustments, other than
those recommended, without obtaining proper approval.
Pressure Fit Parts
When assembling pressure fit parts, use an “anti-seize” or
molybdenum disulfide base compound to lubricate the
mating surface.
Bearings
1. When a bearing is removed, cover it to keep out dirt
and abrasives. Clean bearings in nonflammable
cleaning solvent and allow to drip dry. Compressed
air can be used but do not spin the bearing.
2. Discard bearings if the races and balls (or rollers)
are pitted, scored or burned.
3. If bearing is found to be serviceable, apply a light
coat of oil and wrap it in clean (waxed) paper. Do not
unwrap reusable or new bearings until they are
ready to be installed.
4. Lubricate new or used serviceable bearings before
installation. When pressing a bearing into a retainer
or bore, apply pressure to the outer race. If the bear-
ing is to be installed on a shaft, apply pressure to the
inner race.
Gaskets
Check that holes in gaskets align with openings in the
mating parts. If it becomes necessary to hand fabricate a
gasket, use gasket material or stock of equivalent material
and thickness. Be sure to cut holes in the right location as
blank gaskets can cause serious system damage.
Bolt Usage and Torque Application
1. Use bolts of proper length. A bolt which is too long
will bottom before the head is tight against its related
part. If a bolt is too short, there will not be enough
thread area to engage and hold the part properly.
When replacing bolts, use only those having the
same specifications of the original, or one which is
equivalent.