SECTION 3 - CHASSIS & TURNTABLE
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3.10
OSCILLATING AXLE SYSTEM
The oscillating front axle is attached to the frame by a pivot
pin, which allows all four wheels to remain on the ground
when traveling on rough terrain. The oscillating axle also
incorporates two lockout cylinders connected between the
frame and the axle. The lockout cylinders permit axle oscilla-
tion when the boom is in the transport position (see Section
4.2, Transport Position Sensing System) and drive is com-
manded.
Lockout cylinders lock and hold the axle when drive is not
commanded or when the boom is outside the transport posi-
tion. Cylinders unlock when pilot pressure is applied to the
holding valves mounted on the cylinders and lock when pilot
pressure is removed. Pilot pressure is available from brake
pressure and is controlled by a solenoid operated lockout
valve mounted in the frame. To ensure the lockout valve is
functioning correctly, a NO pressure switch is mounted
between the lockout valve and the holding valves. The system
is “healthy” when pressure trips the pressure switch when the
lockout valve is energized and conversely is healthy when the
lack of pressure resets the pressure switch when the lockout
valve is de-energized.
Failures in the oscillating axle system will cause the control
system to disallow main boom lift up and telescope out, and
tower boom lift up when both booms are within the transport
position and will disallow drive/steer, lift up and telescope out
when either boom is beyond the transport position.
NOTE:
For more detailed information concerning system adjust-
ment and operation, refer to Section 6 - JLG Control Sys-
tem.
3.11 OSCILLATING AXLE BLEEDING PROCEDURE AND
LOCKOUT TEST
Lockout Cylinder Bleeding
To start the test, the axle must be fully oscillated in one direc-
tion. Start with oscillating the axle so that the left lock-out cyl.
is fully retracted (left front tire up), and the right lock-out cyl. Is
fully extended (right front tire down).
ENSURE PLATFORM IS FULLY LOWERED AND BOOM IS CENTERED OVER REAR
AXLE PRIOR TO BEGINNING BLEEDING PROCEDURE. MAKING SURE MACHINE
IS ON A LEVEL SURFACE AND REAR WHEELS ARE BLOCKED, BRAKE WIRE IS
DISCONNECTED.
1.
Making sure machine is on a level surface and rear
wheels are blocked, machine is in transport mode.
2.
Disengage drive hubs.
3.
Use suitable container to catch any residual hydraulic
fluid, place container under the lockout cylinder.
4.
With left lockout cylinder retracted, open bleeder on top
of the cylinder, then have an operator from the platform
(on high engine) feather drive. Activate drive fully.
5.
Close bleeder when there is a steady stream of oil and
not air.
6.
With axle in the same position, go to right lockout cylin-
der and open bleeder at the rod end. Activate drive in
the same manner and close when all air has been
purged.
7.
Close bleeder when there is a steady stream of oil and
not air.
8.
Oscillate axle the other direction, left lock-out cyl.
extended (tire down), right lock-out cyl. retracted (tire
up). Use the same procedure for the bleeder in the rod
end of the left lock-out cyl., Then the piston end of the
right lock-out cyl. then close.
9.
Repeat process one more time to ensure all air has been
purged from the system.
10.
Perform oscillating axle lockout test.
11.
If necessary, repeat steps 1 thru 9.
NOTE:
Bleeding oscillating axles is an infrequent operation per-
formed after hydraulic line failure or lock-out cylinder
repair.
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