JLG 1100S Service Manual - Manual (Page 64)

SECTION 3 - CHASSIS & TURNTABLE
3-22 – JLG Lift – 3121256
3.9 OSCILLATING AXLE SYSTEM (1100SJP)
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 oscillation when the boom is in the transport
position and drive is commanded. The lockout cylinders
will lock and hold the axle when drive is not commanded
or when the boom is outside the transport position. The
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
NC 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 com-
manded to be open and conversely is healthy when the
lack of pressure resets the pressure switch when the lock-
out valve is commanded to be closed. Failures in the
oscillating axle system will cause the control system to
disallow lift up and telescope out when the boom is within
the transport position and will disallow drive/steer, lift up
and telescope out when the boom is beyond the transport
position.
NOTE: For more detailed information concerning system
adjustment and operation, refer to Section 6 - JLG
Control System.
3.10 OSCILLATING AXLE BLEEDING
PROCEDURE AND LOCKOUT TEST
(1100SJP)
Lockout Cylinder Bleeding
To start the test, the axle must be fully oscillated in one
direction. 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 CEN-
TERED OVER REAR AXLE PRIOR TO BEGINNING BLEEDING PRO-
CEDURE. 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 the drive hubs.
3. Use suitable container to catch any residual hydrau-
lic fluid, place container under the lockout cylinder.
4. With the left lock-out cyl. retracted, open the bleeder
on top of the cylinder, then have an operator from
the platform (on high engine) feather drive. Activate
drive fully.
5. Close the bleeder when there is a steady stream of
oil and not air.
6. With the axle in the same position, go to the right
lock-out cyl. and open the bleeder at the rod end.
Activate drive in the same manner and close when
all air has been purged.
7. Close the bleeder when there is a steady stream of
oil and not air.
8. Oscillate the 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 this process one more time to ensure that all
air has been purged from the system.
10. Perform oscillating axle lockout test.
11. If necessary, repeat steps 1 thru 9.
NOTE: Bleeding of the oscillating axles is an infrequent
operation performed after hydraulic line failure and or
lock-out cylinder repair.