JLG G5-18A Service Manual - Manual (Page 46)

Boom
3-14 G5-18A, 2505H, 25.5
3.9.2 Lowering Procedure
a. Retract the boom as follows:
1. Place a suitable receptacle under hose connections.
2. Locate the extend/retract cylinder connection (4 and
5) along the left side of the boom where the hoses
from the valve connect to the steel tube.
3. Label and disconnect hoses from steel tubes along
left side of boom. 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 amount trapped
within each hose.
4. Using hoses and fittings specified previously,
connect jumper hoses between auxiliary hydraulic
power supply and steel tubes (4 and 5) connected to
extend/retract cylinder of affected machine. Ensure
that supply and return lines are installed in proper
order to ensure 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
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 fluid, etc., in, on, near
and around machine.
b. Lower the boom as follows:
1. Place a suitable receptacle under main control valve.
2. Label and disconnect lift/lower cylinder hoses
(6 and 7) from main control valve. Install plugs in
hoses to prevent fluid loss. Cap all fittings and
openings to keep dirt and debris from entering
hydraulic system.
Note: Loss of hydraulic oil is limited to amount trapped
within each hose.
3. Using hoses and fittings specified, connect hoses
between auxiliary hydraulic power supply and hoses
removed from main control valve lift/lower section of
affected machine. Hose (7) is supply (lower) and
hose (6) is return. Connect hoses in proper order to
ensure that boom is lowered, not raised.
4. Use auxiliary power supply to retract lift cylinder.
5. After boom has been lowered, loosen and remove
jumper hoses and reconnect lift/lower cylinder hoses
at 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 fluid, etc., in, on, near
and around the machine.
MAP0040
VIEW FROM LEFT SIDE
4 & 5
MY3000
7
6