JLG 18RS Service Manual - Manual (Page 130)

SECTION 5 - HYDRAULICS
5-40 – JLG Lift – 3121284
NOTE: A small pressure differential of 1.5 bar [22 psi] or less is
acceptable. Zero differential is usually not possible. Mechanical Neutral Adjustment
SERVO ADJUSTMENT
1. Run prime mover at 1800 min¯¹(rpm).
2. If using a PWM signal, ensure the signal is off. Check the
servo pressure gauges. Ensure the differential between
M4 and M5 is less than 1.5 bar [22 psi].
3. Using a 3/4 in hex deep socket, unthread both servo cyl-
inders 2-3 turns. This step ensures the servo cylinders
have no contact with the servo piston.
4. Stroke the pump by turning the control eccentric screw
(or supplying current to solenoid C1) until the servo
pressure at port M4 is 1 to 2 bar [14– 29 psi] greater than
at port M5 and the system pressure gauges indicate dis-
placement. Pressure should be greater at port MA for
clockwise rotation, or MB for counter clockwise rotation.
This also indicates the servo piston is in contact with the
servo cylinder on side M5.
5. Slowly thread the servo cylinder on the M5 side in until
the system pressure differential starts to decrease. Main-
tain servo pressure differential between 1-2 bar [14-29
psi] during this step. Continue turning the servo cylinder
in until the system pressure differential (between ports
MA/MB) is less than 1.5 bar [22 psi]. This procedure sets
the servo and swashplate to mechanical neutral on the
M5 side.
6. To complete setting neutral, repeat steps 1-5 but stroke
the pump in the opposite direction by turning the
eccentric screw in the opposite direction, or by supply-
ing current to solenoid C2. Reverse gauge locations (M4
for M5, MB for MA) from those stated above since the
pump is now stroking the other direction. Figure 5-44. Neutral Adjustment (Bottom View)