JLG 1250AJP Service Manual - Manual (Page 238)

SECTION 3 - 1CHASSIS & TURNTABLE
3-190 – JLG Lift – 3121171
3.30 AUXILIARY POWER SYSTEM
The Auxiliary Power System is intended as a secondary
means of moving the boom in the event of primary power
loss. This system uses an electric motor/pump unit pow-
ered by a 12V battery capable of operating all functions
except drive and controlled boom angle (see Section
4.11, Controlled Boom Angle System). To reduce the
demand on the battery and therefore extend the run time
of the system, the auxiliary power functionality differs from
the primary power functionality. When commanded, the
control system will attempt to use the force of gravity to
operate main lift down, tower lift down, and tower tele-
scope in by supplying pilot pressure to the respective cyl-
inders. If appropriate movement is not detected by the
boom sensors, the auxiliary power system will supply the
hydraulic flow to power the movement conventionally.
The envelope control system (see Section 4.6, Envelope
Control System) remains active during the auxiliary power
operation, however, the functionality of tower lift or main
lift only approximates the normal tower path control (see
Section 4.7, Tower Path Control System) or main boom
control (see Section 4.8, Automatic Main Boom Control
System) functionality. Rather than the normal combined
movements of tower lift, tower telescope, and main lift,
these movements will automatically alternate during com-
mands for tower lift or main lift to approximate the move-
ments made under normal engine power.
3.31 COUNTERWEIGHT
If the counterweight has been removed, ensure the retain-
ing bolts are torqued to the proper value as shown in Fig-
ure 3-78., Counterweight Bolt Torque.