JLG 723A Service Manual - Manual (Page 42)

Boom
3-12 L2906H, 2906H, 3507H, 619A, 723A, 29.6LP, 29.6, 35.7
3. Label and disconnect both extend/retract hoses
(4 & 5). Install plugs in hoses to prevent oil loss. Cap
all fittings and openings to keep dirt and debris from
entering the hydraulic system.
Note: Loss of hydraulic oil is limited to the amount
trapped within each hose.
4. Using the hoses and fittings specified previously,
connect the jumper hoses between the auxiliary
hydraulic power supply and the extend/retract hoses
(4 & 5) of the affected machine. Ensure that the
supply and return lines are installed in the proper
order to ensure that the cylinder is retracted, not
extended.
5. Use the auxiliary power supply to retract the extend/
retract cylinder.
6. Loosen and remove the jumper hoses and
reconnect the extend/retract cylinder hoses.
7. 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.
8. Clean up all debris, hydraulic oil, etc., in, on, near
and around the machine.
b. Lower the boom as follows:
1. Place a suitable receptacle under the main control
valve.
2. Label and disconnect the lift/lower cylinder hoses
(6 & 7) from the main control valve. Install plugs in
hoses to prevent oil loss. Cap all fittings and
openings to keep dirt and debris from entering the
hydraulic system.
Note: Loss of hydraulic oil is limited to the amount
trapped within each hose.
3. Using the hoses and fittings specified, connect the
hoses between the auxiliary hydraulic power supply
and the hoses removed from the main control valve
lift/lower section of the affected machine. Hose (7) is
the supply (lower) and hose (6) is the return.
Connect the hoses in the proper order to ensure that
the boom is lowered, not raised.
4. Use the auxiliary power supply to retract the lift
cylinder.
5. After the boom has been lowered, loosen and
remove the jumper hoses and reconnect the lift/
lower cylinder hoses at the main control valve.
6. 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.
7. Clean up all debris, hydraulic oil, etc., in, on, near
and around the machine.
MZ5370
7
6