JLG 4017PS Service Manual - Manual (Page 80)

Boom
3-42 3706PS, 3707PS, 4014PS, 4017PS, 33.7, 37.6, 37.7
3.21.2 Lowering Procedure
a. Retract the boom as follows:
1. Place a suitable receptacle under the main control
valve.
2. Label and disconnect the extend/retract cylinder
hoses (4 & 5) from the main control valve. Install
plugs in hoses to prevent fluid 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
extend/retract section of the affected machine.
Retract hose (5) is the supply and extend hose (4) is
the return. Connect the hoses in the proper order to
ensure that the cylinder is retracted, not extended.
4. Use the auxiliary power supply to retract the extend/
retract cylinder.
5. Loosen and remove the jumper hoses and
reconnect the extend/retract cylinder hoses.
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 fluid, 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 fluid 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 lower the boom.
5. Loosen and remove the jumper hoses and
reconnect the lift/lower cylinder hoses.
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 fluid, etc., in, on, near
and around the machine.
MAM1270
6
4
7
5
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