JLG 1850SJ Service Manual - Manual (Page 259)

SECTION 5 - BASIC HYDRAULIC INFORMATION & HYDRAULIC SCHEMATICS
3121619 – JLG Lift – 5-89
Control Adjustment
ESCAPING HYDRAULIC FLUID UNDER PRESSURE CAN HAVE
SUFFICIENT FORCE TO PENETRATE SKIN CAUSING SERI-
OUS INJURY AND/OR INFECTION. RELIEVE PRESSURE IN
SYSTEM BEFORE REMOVING HOSES, FITTINGS, GAUGES,
OR COMPONENTS.
UNINTENDED MOVEMENT OF MACHINE OR MECHANISM
MAY CAUSE INJURY TO TECHNICIAN OR BYSTANDERS.
SECURE MACHINE OR DISABLE/DISCONNECT MECHANISM
WHILE SERVICING.
CONTAMINATION CAN DAMAGE INTERNAL COMPONENTS AND VOID THE MAN-
UFACTURER’S WARRANTY. TAKE PRECAUTIONS TO ENSURE SYSTEM CLEANLI-
NESS WHEN REMOVING AND REINSTALLING SYSTEM LINES.
PC CONTROL SETTING
1. Install pressure gauge in port M1 to measure system
pressure. Install pressure gauge in case drain port L1 or
L2 to measure case pressure.
2. Start prime mover and allow fluid to reach normal oper-
ating temperature. Operate a hydraulic function to its
full extension, loading the pump at maximum pressure
and zero flow.
3. Loosen PC set screw and turn PC adjusting plug until
4100 psi (283 bar) is indicated on pressure gauge at port
M1. Clockwise rotation increases pressure, counterclock-
wise rotation decreases; approximate gain 610 psi (42
bar) per turn.
NOTE: If pressure does not increase, an external system relief valve
may require adjustment. External system relief valve must
be set above PC setting for proper operation.
4. Hold PC adjusting plug in position. Torque PC set screw
to 5.5 - 8 lb ft-lb (7.5 -10.8 Nm). Stop prime mover,
remove pressure gauges, and return system to normal
operating configuration.
NOTE: If pressure does not increase, an external system relief valve
may require adjustment. External system relief valve must
be set above PC setting for proper operation.
Figure 5-117. PC Control Setting