JLG 450AJ ANSI Service Manual - Manual (Page 68)

SECTION 2 - PROCEDURES
2-50 – JLG Lift – 3120749
The needed travel of the carburetor determines how far
out on the Actuator arm the rod is to be attached. In most
cases, the carburetor should be moved from closed to
above 10 degrees from full open as the Actuator is moved
min. to max. THEN ALTER THE LENGTH OF THE ROD
SLIGHTLY (PERHAPS 0.030"), SO THAT THE ACTUATOR
IS JUST OFF ITS INTERNAL STOP, AND IS PULLING THE
BUTTERFLY AGAINST ITS STOP. This insures that the car-
buretor can fully close to idle on load dumps, minimizing
overspeeds.
Examine the system for springs, such as carburetor return
springs. These should be removed. Some automotive car-
buretors (as opposed to industrial carburetors) contain
internal springs for accelerator pumps, etc. These may
make good governing difficult, or even impossible. For
this, and other reasons, industrial carburetors are much to
be preferred.
Move the linkage slowly through its travel, and look for
any binding or unexplained forces. Correct any before
going further.
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 atmo-
spheric 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 ter-
minal. If this cannot be done, for some reason, go by ded-
icated 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 wir-
ing before applying power.
Check-Out and Initial Start-Up Procedures
Before proceeding, familiarize yourself with the locations
of the various adjustment pots. There are two types of
adjustment pots.
Multi-Turn Adjustment (High Engine, Mid
Engine, Overspeed, Starter Lockout)
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
pot is 25 turns, and one full turn will change speed about
100-200 rpm. This pot is protected by a slip clutch at each
end, and will not be harmed by moderate over-adjust-
ment. However, the Governor will not function while the
pot is past full travel. If you suspect you may have over-
adjusted the High Engine pot, or have lost track of where
you are, turn the pot 25-30 turns CCW, then back 10-12
turns CW to get back into the range of normal adjustment.