JLG 800A_AJ Service Manual - Manual (Page 164)

SECTION 3 - CHASSIS & TURNTABLE
3-108 – JLG Lift – 3120858
Many “governing” problems are really caused by binding
of the butterfly and its shaft in the carburetor. This is
caused by loading due to vacuum under the butterfly and
atmospheric pressure above when the engine is running.
These forces cannot be felt when the engine is not run-
ning. Therefore, start the engine while carefully controlling
the speed by hand, and feel for binding or airload forces.
Needle bearings on the butterfly shaft are available on
many industrial carburetors to deal with this problem. Any
tendency on the butterfly stick must be corrected.
Mounting-Controller
Select a reasonably cool, dry, and vibration free location.
The rear cover will probably need to be removed during
set-up in order to make adjustments for speed setting and
gain. You may wish to defer final installation until this is
done.
After completing these adjustments, replace cover. Mount
so that water cannot pool on this cover. Always mount the
controller with the strain relief down. This will prevent
water from entering thru the cable, also place the vent
hole in the bottom of the controller down.
Wiring
See wiring diagram for details of hook-up.
Use #16 wire minimum.
Keep all wiring to the Governor as short as is practical.
Go directly from the controller ground terminal (B of the 8
pin connector) by dedicated wire, to the battery “minus”
terminal. If this cannot be done, for some reason, go by
dedicated wire to a very good engine ground.
A properly functioning engine electrical system will supply
13.5 - 14.8 VDC when the engine is running. If wiring size
is adequate, with good connections and proper grounds,
you will get this reading between the wires terminals A & B
of the 8 pin connector when the Governor is controlling
engine speed. Verify this. Improper hook-up can damage
electronics. Re-check wiring before applying power.
Power Distribution
8 Pin Connector
Pin:
a. 12 VDC from the make before break oil pressure
switch. This switch provides power to pin A
when the ignition is on and the engine is not run-
ning (no oil pressure), or when the ignition is
turned off when the engine is running (has oil
pressure).
b. Ground.
c. Tach signal from the engine ignition system.
d. Tach signal from the engine ignition system.
e. Control signal to operate the Actuator.
f. Control signal to operate the Actuator.
g. Removes ground from the start lock out relay
when the engine is running above the start lock
out set point. A 20 turn pot is provided to adjust
this set point. (usually around 500 RPM)
h. Removes ground from the overspeed relay if this
point is exceeded. A 20 turn pot is provided to
adjust this set point.(usually around 5000 RPM)
4 Pin Connector
Pin:
a. Input from the elevation limit switches to allow
high engine to operate.
b. Input from the high engine switch.
c. Input for mid engine from one of the following:
The engine low coolant temperature switch, plat-
form footswitch, or a ground control directional
switch.
d. Provides ground to lockout start when the
engine RPMS exceed the set point.
Check-Out and Initial Start-Up Procedures
Before proceeding, familiarize yourself with the locations
of the various adjustment pots.
Adjustments
High engine
Mid engine
Start lockout
Over speed lockout
Factory adjust
Gain
High Engine:
This adjustment is made by turning the 1/8" brass screw
clockwise (CW) to increase speed, and counterclockwise
(CCW) to decrease speed. The adjustment range of the
high engine pot is 25 turns, each turn will change engine
speed by about 100 to 200 RPMS. This pot is protected by
a slip clutch at each end and will not be harmed by mod-
erate over-adjustment. However the governor will not
function when the pot is past full travel. If you suspect that
you may have over-adjusted the high engine pot, or have
lost track of where you are, turn the pot 25 to 30 turns out
(CCW), then turn in (CW) 10 turns. This will get you back
into the range you should be in. Make the high engine
adjustment first, then gain, then reset high engine.