JLG 601S ANSI Service Manual - Manual (Page 103)

SECTION 3 - CHASSIS & TURNTABLE
3120746 – JLG Lift – 3-63
b. Governor is unstable at light-load or no-load.
See “Linkage” for carbureted engines.
c. Governor experiences sudden, momentary
spikes toward max. at random intervals, then
recovers.
1.Look for loose wiring or momentary shorts in
wiring.
2.Noise or occasionally missing speed signal.
d. Speed seems to slowly wander (5-15 second
periods) around at speed, particularly at higher
loads. See item 2a. 3 concerning excessive
forces at Governor during running.
3. Governor not tuned or adjusted for engine/applica-
tion.
The basic adjustment to set sensitivity/stability is the Gain
pot. A good starting point for many engines is full CCW,
then CW 1/3 turn. (See “Governor adjustment” section).
To increase stability, turn CCW. If satisfactory governing
cannot be achieved with this one adjustment, the factory
adjustment may be needed. Normal starting point for this
adjustment is fully CCW, then CW 1/4 turn. (Before chang-
ing this pot, mark the original position).
NOTE: If problems occurs with the Governor overshooting
when a large load is released from the engine, such
as driving up a hill and stopping. There is usually
one of two things:
1.Gain adjustment is too far CCW.
2.Mechanical preload between the carburetor
and actuator is to large, this should be no
greater than 1/2 to 1 ball dia.
3.19 THROTTLE CHECKS AND
ADJUSTMENTS - DEUTZ ENGINE
(PRIOR TO S/N 61306)
General
The throttle control system on the Deutz engine includes
the positional controller and the actuator.
Four LEDs are incorporated in the controller. They are as
follows:
• Red - failure: signals a problem with the system -
needs service or adjustment
• Green - clutch engaged; operation normal while sys-
tem is powered.
• Amber - motor extend
• Amber - motor retract
The controller is designed so that when the system volt-
age reaches 10.5 volts, the actuator clutch will be
released and the motor drive turned off in order to prevent
unpredictable operation from occurring.
When a failure condition occurs (i.e. position time-out) the
controller will release the clutch and turn off the actuator
motor. This will prevent unnecessary motor wear.
Table 3-8.Position Controller Truth Table
Control Wiring
Actuator Position
Black Red White Green
GND OFF X X OFF POSITION (Freewheel)
GND +12 VDC OFF OFF POSITION 1 (See Adjustments)
GND +12 VDC +12 VDC OFF POSITION 2 (See Adjustments)
GND +12 VDC OFF +12 VDC POSITION 3 (See Adjustments)
GND +12 VDC +12 VDC +12 VDC POSITION 4 (See Adjustments)
GND = POWER SUPPLY OR BATTERY GROUND
OFF = GROUND OR OPEN CIRCUIT
X = DON’T CARE
+12 VDC = +12 VOLT POWER SUPPLY OR BATTERY SYSTEM, VIA A 5 AMP FUSE
OR CIRCUIT BREAKER
TRIMMER ADJUSTMENTS LED INDICATORS
1 - POSITION 1 CW=RETRACT
2 - POSITION 2 CW=RETRACT
3 - POSITION 3 CW=RETRACT
4 - POSITION 4 CW=RETRACT R - RETRACT INDICATOR (AMBER)
E - EXTEND INDICATOR (AMBER)
C - CLUTCH INDICATOR (GREEN)
F - FAILURE INDICATOR (RED)