JLG G12-55A Service Manual - Manual (Page 67)

3-31 G10-55A, G12-55A
Boom
3. Using the hoses and fittings specified, connect the
hoses between the auxiliary hydraulic power supply
and the tubes removed from the main control valve
lift/lower section of the affected machine. Lift tube (3)
is the return and lower tube (4) is the supply.
Connect the hoses in the proper order to ensure that
the boom is lowered, not raised.
4. Remove the previously installed boom support.
5. Use the auxiliary power supply to slowly lower the
boom.
6. Loosen and remove the jumper hoses, caps, plugs
and reconnect the lift/lower cylinder tubes. Torque as
required.
7. Install the previously remove clamps securing the
extend/retract and lift/lower cylinder tubes.
8. Install the plastic cover over the top of the main
control valve.
9. Transfer any hydraulic oil into a suitable, covered
container, and label the container as “Used Oil.”
Dispose of used oil at an approved recycling facility.
10. Clean up all debris, hydraulic oil, etc., in, on, near
and around the machine.
11. Remove the Do Not Operate Tag on both the ignition
key switch and steering wheel.