JLG 450AJ ANSI Service Manual - Manual (Page 69)

SECTION 2 - PROCEDURES
3120749 – JLG Lift – 2-51
Single-Turn Adjustment (Gain, Factory
Adjust)
This pot is 3/8" square and has a 1/8" plastic screw in its
center. Be gentle! This pot turns 270 degrees, and over-
turning will break the internal stops, making adjustment
impossible. Turning this pot CW increase Governor sensi-
tivity. On most applications, best operation is achieved
with the pot set as shown in diagram below.
NOTE: These settings are factory set, Start Lockout, Fac-
tory Adjust and Overspeed. They are conformally
coated by P.G. and should not need to be reset.
Assuming that the Actuator and Controller are mounted,
the wiring is run and checked, and that the linkage is
properly installed, proceed as follows:
1. Turn ignition switch on. Do not start engine. Actuator
should kick toward max. fuel once, and then imme-
diately return to min. fuel. If not, see Troubleshoot-
ing.
2. Use multimeter to check battery voltage at battery
terminals, and record. Now check voltage at the
machine connection points for terminals A & B of the
8 pin connector on the E-331 (A is +, B is -). Voltage
reading should be the same as at battery. If not, shut
down, and correct wiring.
3. Hold the linkage back by hand, so as to control
engine speed manually. Start engine, set vehicle
controls to obtain High Engine speed, gradually
release the linkage, and adjust the speed-set as
needed to set the speed as desired. If engine speed
surges, reduce Gain a little, as required (CCW).
4. Re-check voltage between terminal A & B as in step
2. Voltage reading should be between 13.5 - 14.6
VDC.
5. Carefully adjust Gain. You are looking for the best
compromise between quick response and good sta-
bility. Make very small adjustments, then load and
unload engine, or pull linkage back slightly and
release. Usually, a good set-up is one that makes 1
to 3 small bounces and then steadies down after a
large change. Too much Gain shows up as a rapid
(once per second) instability, most commonly at
light loads. Too little Gain shows up in large over-
shoots on start-up or large load changes, and gen-
erally sluggish operation.
6. Make final adjustment to the High Engine Pot.
7. Set machine controls to obtain the mid-engine
speed. Adjust the mid-engine pot as needed to
obtain the speed desired.
8. The start lockout adjustment is factory set. If neces-
sary, he starter lockout pot may be adjusted to
obtain dropout of the starter as the engine attains
running speed. Normally this is around 500 RPM.