Lull 644B Operation Manual - Manual (Page 37)

Supplement P09836 Origin 1/98 1
GENERAL OPERATING PROCEDURES - SUPPLEMENT
DRIVE LOCKOUT OVERRIDE
Important: Read and understand the following
instructions BEFORE using the optional
Drive Lockout Override System!
Theory of Normal Operation
This machine is equipped with a stabilization system
that does several things to increase lateral (side-to-
side) stability.
When the boom is raised above 20° elevation:
•
The transmission is limited to first and second
gears.
•
The rear oscillation lock cylinder is limited to slow
(orificed) movement.
•
The speed of the frame tilt function is limited.
When the boom is raised above 40° elevation:
•
The rear axle stabilization cylinder is locked,
preventing the frame from rotating on the rear axle.
•
The transmission is disengaged, stopping drive
capabilities.
These functions help prevent tipover accidents which
can cause serious injuries and death. The
owner/operator manual describes the normal use and
operation of a telescopic handler and tells the operator
to carry the load and forks as low as possible, but not
above eye level.
The Rear Oscillation Lock System stops the machine
from driving when the boom angle is above 40°. Driving
with the boom elevated (loaded or empty) can be very
dangerous, especially on uneven terrain. The
machine’s center of gravity is highest when the boom is
elevated, which makes it less stable laterally as the
boom is raised higher. Improperly driving the machine
introduces dynamics that can add to instability and lead
to a tipover.
Diagram 1: Stability Triangle (Front axle locked and
frame free to rotate on rear axle)
Diagram 2: Stability Rectangle (Front and rear
axles locked, preventing frame from rotating)
When the boom angle is below 20° the machine
operates with a freely oscillating rear axle to negotiate
rough terrain. (See Diagram 1)
When the boom angle is above 20°, the rear axle
cylinder is orificed, slowing movement of the frame on
the rear axle. This increases the lateral (side-to-side)
stability.
When the boom angle is above 40°, the rear axle
cylinder locks, preventing the frame rotating on the rear
axle. This changes the stability diagram from a triangle
to a rectangle (when viewed from above) and
substantially increases the machine’s lateral stability.
(See Diagram 2)
General Description, Drive Lockout
Override System
In some special applications, it is not possible to carry
or place the required load unless the machine is driven
with an elevated boom. The Drive Lockout Override
System is designed to allow this and MUST BE USED
WITH EXTREME CARE!
The Drive Lockout Override System does two things
when engaged with the boom angle above 40°:
•
Allows the transmission to be engaged in first gear
only.
•
Unlocks the rear oscillation lock cylinder and
allows very slow (orificed) movement. This
increases dynamic lateral stability while the
machine is being driven.