User Manual

ManualsBrandsJLG ManualsSpecial machinery723A Service Manual

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 mac hine, the exte nd/retract

cylinder MUST BE fully retracted prior to retracting

the li ft cylinder. If circ umstances prevent retrac tion 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

Supp ly hydr auli c oil must be com patible with hy drauli c

oil shown in Section 2.4, “Fluids, Lubricants and

Capacities.”

MZ5370