JLG G6-42A Service Manual - Manual (Page 69)

3-31 G6-42A, G9-43A, G10-43A
Boom
3.14 EMERGENCY BOOM LOWERING
PROCEDURE
3.14.1 Equipment and Supplies Required
Auxiliary Hydraulic Power Supply:
• Portable hydraulic unit or another machine with
an auxiliary hydraulic power supply with a
capacity to hold up to 22 gal (83 L) of hydraulic
oil from the machine during lowering process.
Note: If another machine is being used, the hydraulic
reservoir must be drained to accept a minimum of 22 gal
(83 L) of hydraulic oil before attempting this procedure.
• Standard Mechanic Tools.
Hoses:
• Two Hydraulic Hoses - Approximately 10 ft
(3,0 m) each, with a minimum I.D. of
0.375 in (9,5 mm) and a minimum rating of
4000 psi (275,8 bar).
G6-42A - Fittings:
• Two -10 ORFS Caps
• Two -10 ORFS Plugs
Adaptors:
• Two -10 ORFS 90° Adaptors
G9-43A/G10-43A - Fittings:
• Two -12 ORFS Caps
• Two -12 ORFS Plugs
Adaptors:
• Two -12 ORFS 90° Adaptors
Note: The adaptor size may vary depending on the
hose ends of the auxiliary hydraulic power supply.
3.14.2 Lowering Procedure
a. Retract the boom as follows:
1. If equipped with Personal Work Platform, rescue
occupants prior to performing procedure.
2. Properly support the boom before attempting to
proceed with the emergency boom lowering
procedure.
3. Place a Do Not Operate Tag on both the ignition key
switch and steering wheel.
4. Properly support the boom as required.
5. Place a suitable receptacle under the tube/hose
connections.
6. Remove the plastic cover from the main control
valve.
WARNING
To avoid instability of the machine, the extend/retract
cylinder MUST BE fully retracted prior to retracting the
lift cylinder. If circumstances prevent retraction of the
extend/retract cylinder first, lower the lift cylinder the
minimum amount necessary and resume retraction of
the extend/retract cylinder as soon as possible in
accordance with the machines load chart.
WARNING
Properly support the boom before attempting to
proceed with the emergency boom lowering
procedure.
WARNING
If possible, safely remove and/or secure the load on
the machine before starting the boom lowering
procedure. If load cannot be removed, the machine
load chart MUST be followed.
NOTICE
EQUIPMENT DAMAGE. Auxiliary Hydraulic Power
Supply hydraulic oil must be compatible with hydraulic
oil shown in Section 2.4, “Fluids and Lubricant
Capacities.”
WARNING
Loss of hydraulic oil is limited to the amount trapped
within each tube/hose. Slowly loosen each hydraulic
tube/hose fitting to release any possible hydraulic oil
pressure that may be trapped between the main
control valve and the counterbalance valve of the
extend/retract cylinder or the lift/lower cylinder.