Lull 944E-42 Service Manual - Manual (Page 51)

3.3 Model 644E-42/944E-42 Rev. 6/04
Boom
3.2 BOOM SYSTEM
3.2.1 Boom System Description
The boom operates via an interchange among the
hydraulic and mechanical systems. Components
involved include the joystick, attachment tilt cylinder,
Extend/Retract cylinder, lift/lower cylinder, slave
cylinders, extend and retract chains, various pivots,
supporting hardware and other components.
3.2.2 Boom System Operation
The boom assembly consists of inner, intermediate, and
outer booms. Boom extension and retraction is
accomplished via hydraulic power and the mechanics of
the chain system.
As the Extend/Retract hydraulic cylinder, which is
anchored at the rear of the intermediate boom and the
rear of the outer boom begins to extend, it forces the
intermediate boom out of the outer boom.
The inner and outer booms are connected by extend and
retract chains. These chains are routed around sheaves
on the intermediate boom. As the intermediate boom is
forced out, the extend chain pulls the inner boom out of
the intermediate boom.
As hydraulic pressure is applied to the retract port on the
Extend/Retract cylinder, the intermediate boom is pulled
back into the outer boom, and the retract chain pulls the
inner boom back into intermediate boom.
This mechanical linkage formed by the chains and
supporting hardware, extends and retracts the inner
boom as the intermediate booms is extended and
retracted by the Extend/Retract cylinder.
The outer boom does not extend or retract, but lifts and
lowers via action of the lift/lower cylinder.
3.3 BOOM ASSEMBLY MAINTENANCE
The boom assembly consists of the inner, intermediate
and outer booms and supporting hardware.
IMPORTANT: Boom replacement must be completed in
sequence, one boom section at a time, as described in
these instructions. Replacement of two or more boom
sections as a unit requires special considerations that
are not covered in these instructions.
IMPORTANT: Before removing the inner boom, the
carriage or any other attachment must be removed from
the quick attach.
The inner, intermediate and outer boom removal
instructions must be completed in sequence. The inner
boom must be removed before removing the intermediate
boom. The inner boom and intermediate boom must be
removed one at a time before removing the outer boom.
Note: A step ladder or some other safe means of
accessing the boom will be necessary.
Before beginning, conduct a visual inspection of the
vehicle, work area and task about to be undertaken.
Read, understand and follow these instructions.
During servicing of the boom, perform the following:
1. Check wear pads for excessive wear. (Refer to
Section 3.5, “Boom Wear Pads.”)
2. Check chain wear and tension adjustment. (Refer to
Section 3.4, “Boom Chains.”)
3. Apply grease at all lubrication points (grease fittings).
(Refer to the appropriate Owners/Operators Manual
for lubrication information.)
4. Check for proper operation by operating all boom
functions through their full range of motion several
times.
WARNING:
DO NOT service the vehicle
without following all safety precautions as
outlined in the “Safety Practices” section of this
manual. Failure to follow the safety practices
may result in death or serious injury.