JLG 800A_AJ ANSI Service Manual - Manual (Page 163)

SECTION 3 - CHASSIS & TURNTABLE
3120740 – JLG Lift – 3-107
Mounting-Actuator
The Actuator may be mounted in any attitude - there is no
preferred orientation.
With no power applied, the Actuator is spring-loaded to
the minimum fuel position. The Actuator output shaft
rotates toward the maximum fuel position against this
spring through electrical power from the controller. This
rotation is CW (clockwise) on one side of the Actuator, and
CCW (counterclockwise) on the other. If necessary,
reverse the Actuator on its mounting plate so that the
desired direction of rotation is on the desired side to
match the fuel system direction of travel.
Before selecting the mounting location, consider the link-
age that will be required to connect the Actuator output
arm to the butterfly or fuel valve. Read the following sec-
tion on linkages before deciding on a mounting location!
1. Mount Actuator rigidly to engine location which will
permit a short, straight linkage to the carburetor or
fuel valve. Avoid very hot areas.
Linkage
1/4" -28 threaded rod and low friction rod-end bearings
are recommended for linkage materials.
Keep the linkage as short and as straight as possible.
The linkage must not rub against the engine, brackets,
hoses, etc. The linkage must be free of friction and lost
motion or “slop”.
The following sketch indicates the proper linkage geome-
try for most installations.
Note that the angle between the carburetor arm and the
rod is 70 degrees with the engine at idle. This is highly
desirable! Note also that the Actuator arm travels equally
on either side of a 90 degree angle with the rod. This
angular arrangement will give the proper mechanical gain
for good stability and performance. It may be necessary to
rotate the carburetor arm relative to the butterfly to
achieve this. This can usually be done, and is usually
worth the effort! Below are some workable installations,
with good linkages. Remember, the Actuator can be
turned 180 degrees on its mounting to “reverse” the
spring-loaded direction. Also, the Actuator can be
mounted in any attitude.
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.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.