JLG 740A, Service And Maintenance Manual

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SECTION 3 - CHASSIS & TURNTABLE
3-160 – JLG Lift – 3121160
Cooler Core Cleaning (Exterior)
Remove leaves, papers, etc. from outside face. Use com-
pressed air and carefully blow through the core from the
inside of the canopy (through fan assembly or remove fan
assembly).
DO NOT use high pressure air or pressure washer.
NOTE: Oil cooler core is aluminum, if this does at some
point require internal cleaning, this is best done by a
suitable equipped radiator shop. Internal cleaning is
NOT a normal maintenance item if the oil is main-
tained in good condition.
Adding/Changing Compressor Oil
Ensure all pressure is relieved from the system. Check oil
level with unit level, otherwise a false oil level indication
will occur.
1. Remove oil fill plug located on main compressor
base casting.
NOTE: This can be done without lifting canopy.)
2. Carefully add lubricant and monitor oil level, allow
time for oil to level out. A complete refill is approxi-
mately 5 1/4 quarts (5 liters). Correct oil level is mini-
mum to bottom threads on oil fill port up until oil
runs out of port. Overfill can only occur if unit is out
of level.
3. Refit oil fill cap tightly by hand.
4. Run unit and recheck oil level after shutdown, allow-
ing time for oil to settle.
Oil drain is provided with short drain hose. This can be
routed to a more convenient location if required, depen-
dent upon installation. Use only Schedule 80 pipe or suit-
ably rated hose.
NOTE: Fill cap has a vent release hole as a safety feature
and to act as a ”tell-tale”. If air escapes while
unscrewing the fill cap, then the system still has
pressure. Re-tighten the cap and wait until all pres-
sure is relieved.
Pressure Adjustments
Before adjusting the pressure control system it is neces-
sary to determine the rated full load pressure setting.
These can be found in the Specification Section.
PRESSURE SWITCH LOCATION:
The pressure switch is located directly behind the cooling
fan inside a black plastic box. Removing the one single
screw from the bottom of the plastic cover allows the
cover to be removed exposing the two adjustment screws
at the top and also exposes the electrical terminations.
ADJUSTMENTS SHOULD BE MADE WITH COMPRESSOR
SWITCHED OFF SINCE ELECTRICAL TERMINALS INSIDE PRES-
SURE SWITCH WILL BE EXPOSED AND OPENING THE CANOPY
EXPOSES BELT DRIVE SYSTEM.
PROCEDURE FOR SETTING:
1. Start compressor and allow to warm up. NOTE -
Pressure reading on gauge with service valve
closed. Switch off compressor.
2. Adjustment screws on pressure switch. Steel slotted
screw (L.H. side upper) will adjust both cut-out and
cut-in pressures together. Screw in clockwise to
increase screw out counter clockwise to decrease.
Plastic head slotted screw (R.H. side upper) will per-
mit changes to cut-out pressure (higher pressure)
without affecting cut-in pressure. (ie. changes differ-
ential pressure range) screw in clockwise to
increase and counterclockwise to decrease upper
pressure setting.
Nominal differential setting 25 to 30 psi (1.7 to 2.0
Bar). This
is to reduce load/unload cycle in cases
where minimal air usage or leaks in hoses/connec-
tions may occur. The recovery period from unload to
load is rapid with the screw compressor and this ini-
tial setting will suit most applications.
It is suggest to make adjustments in % turn incre-
ments then close canopy, restart and check pres-
sure. Re-adjust as necessary.
When desired pressure is set, replace switch cover
and close canopy for operation.
INCREASING AIR PRESSURE WILL INCREASE THE REQUIRED
COMPRESSOR H.P. BE SURE THE HYDRAULIC POWER SUPPLY IS
CAPABLE (HYDRAULIC PRESSURE) OTHERWISE THE COMPRES-
SOR MAY STALL OUT DURING OPERATION DUE TO INCREASED
POWER REQUIREMENT.