JLG 4394RT Service Manual - Manual (Page 37)

SECTION 3 - CHASSIS, PLATFORM & SCISSOR ARMS
3121249 – JLG Lift – 3-1
SECTION 3. CHASSIS, PLATFORM & SCISSOR ARMS
3.1 OPERATING CHARACTERISTICS
Leveling Jacks
The machine may be equipped with auto leveling jacks.
These leveling jacks are operated through one switch
unlike the traditional four switch system. The leveling
jacks are operated by a bang bang valve.
NOTE: The engine speed will drop when the leveling jacks
are in contact with the ground.
1. Activate the leveling jack button located on the plat-
form control box.
2. Extend the jacks by moving the joystick forward.
NOTE: Once all four jacks make contact with the ground the
system will go from set mode into level mode. At this
point the engine will return to idle.
3. The tilt indicator will go out once the machine is
level.
NOTE: If the machine is not level it will not lift. If you hit the
end of stroke on any of the cylinders you cannot lift
the machine.
NOTE: There is a limit switch on each cylinder that senses
when the cylinder is fully retracted when all four are
fully retracted, the stowed light in the platform control
box will light.
If you receive a 2/5 flash code through the system
fault light at the platform control station the machine
is unable to level. You must reposition and try again.
The jacks are operational (extend or retract) if the machine
is in the stowed position. The proximity sensor and rotary
sensor together must sense that the machine is stowed. A
failure of either sensor will prevent the jacks from being
activated.
Power Deck
The power deck is operated through a non proportional
valve. This will not effect any other function when acti-
vated.
BE SURE AND RETRACT ANY POWER DECK BEFORE LOWERING
MACHINE.
Generator
When the generator switch is activated, the engine RPM
will increase to 2000 RPM for a 60 Hz generator or 1700
RPM for a 50 Hz generator.
When a function is selected for operation, which requires
a higher engine speed than the generator, the generator
will automatically shut off during the operation of the func-
tion. Once the function has stopped, the generator will be
active again.
Lift
There is a flow control valve which controls both the lift up
and lift down speeds.
Anytime you abruptly change lift directions, there is a
three second delay between lift up and lift down.
Drive
If driving at high drive up a grade and you hit an 8° incline,
the drive function will cut back to mid drive speed. The
drive pump will shift back into high drive once the incline
decreases to 5°. There will be a 2 second delay before the
machine goes back into high drive.
3.2 TIRES, WHEELS & DRIVE ASSEMBLY
Tire Inflation
The air pressure for pneumatic tires must be equal to the
air pressure that is stenciled on the side of the JLG prod-
uct or rim decal for safe and proper operational character-
istics.
Tire Damage
For pneumatic tires, JLG Industries, Inc. recommends that
when any cut, rip, or tear is discovered that exposes side-
wall or tread area cords in the tire, measures must be
taken to remove the JLG product from service immedi-
ately. Arrangements must be made for replacement of the
tire or tire assembly.
For polyurethane foam filled tires, JLG Industries, Inc. rec-
ommends that when any of the following are discovered,
measures must be taken to remove the JLG product from
service immediately and arrangements must be made for
replacement of the tire or tire assembly.
• a smooth, even cut through the cord plies which
exceeds 3 inches (7.5 cm) in total length
• any tears or rips (ragged edges) in the cord plies which
exceeds 1 inch (2.5 cm) in any direction
• any punctures which exceed 1 inch in diameter