JLG 723A Service Manual - Manual (Page 41)

3-11 L2906H, 2906H, 3507H, 619A, 723A, 29.6LP, 29.6, 35.7
Boom
b. Prop Removal
1. If needed, start machine and slowly raise the boom
until the boom prop is clear of the lift/lower rod end.
2. Remove the o-rings (2) and boom prop (1) from the
cylinder. Return the boom prop to the proper location
and secure.
3. Lower boom, shut engine OFF.
3.9 EMERGENCY BOOM LOWERING
PROCEDURE
In case of an emergency, engine, hydraulic or electrical
failure, use the following procedure to retract and/or lower
the boom.
3.9.1 Equipment and Supplies Required
Auxiliary Hydraulic Power Supply:
• Portable hydraulic unit or another machine with
an auxiliary hydraulic power supply with a capac-
ity to hold up to 11,4 L (3 gal) of hydraulic oil from
the machine during lowering process.
Hoses:
• Two Hydraulic Hoses - Approximately 3,0 m
(10 ft) each, with a minimum I.D. of
9,5 mm (0.375 in) and a minimum rating of
275,8 bar (4000 psi).
Fittings:
• Two 25,4 mm (1 in) - 14 ORFS Caps
• Two 25,4 mm (1 in) - 14 ORFS Plugs
Note: Machine extend/retract and lift/lower hoses are -
14 ORFS. The adaptor size may vary depending on the
hose ends of the auxiliary hydraulic power supply.
3.9.2 Lowering Procedure
a. Retract the boom as follows:
1. Place a suitable receptacle under the hose
connections.
2. From the rear of the machine, locate the extend/
retract cylinder connection (4 & 5) at the rear of the
main control valve.
NOTICE
EQUIPMENT DAMAGE. DO NOT operate with the
boom prop in place. Damage to the boom prop and/or
the lift/lower cylinder could occur.
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.
NOTICE
EQUIPMENT DAMAGE. Auxiliary Hydraulic Power
Supply hydraulic oil must be compatible with hydraulic
oil shown in Section 2.4, “Fluids, Lubricants and
Capacities.”
MZ5370
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