JLG 340AJ Service Manual - Manual (Page 227)

SECTION 5 - HYDRAULICS
3121259 – JLG Lift – 5-69
Mechanical Neutral Adjustment
SERVO ADJUSTMENT
1. Run prime mover at 1800 min 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.
7. Remove all gauges and replace gauge port plugs. You
can find wrench sizes and plug torques in the Plug size
and torque chart.
SERVO ADJUSTMENT SIDE M4
1. Run prime mover at 1800 rpm.
2. If using a PWM signal to set mechanical neutral, start
with the electronic control testing tool off (no current to
either solenoid). Check to be sure the servo pressure dif-
ferential is less than 1.5 bar [22 psi]. Reference Control
Neutral Adjustment.
3. Turn neutral adjust excenter screw (or supply current to
solenoid C2) until the servo pressure at port M5 is 1 - 2
bar [14- 29 psi] greater than at port M4.
4. The system pressure differential must be greater than
zero and the pressure at port A (B for clockwise rotation)
must be greater than the pressure at port B (A for clock-
wise rotation). This step ensures the servo is in contact
with the servo cylinder on side M4.
5. Slowly turn in the servo cylinder on the M4 side until the
system pressure differential starts to decrease. The servo
pressure differential must be maintained between 1-2
bar [14-29 psi] during this step. Continue turning in the
servo cylinder until the system pressure differential is
less than 1.5 bar [22 psi]. This procedure sets the servo
and swashplate to mechanical neutral.
VERIFY NEUTRAL SETTING
1. If using a PWM signal to set mechanical neutral, check
that servo pressure differential is less than 1.5 bar [22
psi]. Refer to Control Neutral Adjustment.
2. To verify mechanical neutral, provide current to solenoid
C1,or turn neutral adjust excenter screw, until the servo
pressure differential is 3 bar [43 psi]. The system pres-
sure differential must be below 1.5 bar [22 psi]. Repeat
test on solenoid C2 side.
3. The current required to set the servo pressure differen-
tial to 3 bar [43 psi] should be the same for each sole-
noid. Refer to TS-392.
4. If using neutral adjust excenter screw to set mechanical
neutral, reset control neutral.