Manitowoc Grove GRT8120, Operator'S Manual

Page: 306 / 448

OPERATING PROCEDURES GRT8120 OPERATOR MANUAL
4-176
Published 3-22-2021, Control # 702-02
PRELOAD CHECK
After crane has been readied for service, an operational
check of all crane functions (with no load applied) should be
performed. Refer to
Craning Functions , page 4-19 for details
as to how to operate the different crane functions.
Preload check is as follows:
1. Extend and set outriggers and level crane.
2. Raise, lower, and swing boom right and left at least 45°.
3. Fully telescope boom out and back in at a 75° boom
angle, ensuring all sections extend and retract properly.
4. With boom fully retracted and at maximum boom angle,
lower the hook block/overhaul ball to near ground level.
Fully extend the boom while keeping the block/ball at
near ground level.
5. With a load applied, fully retract the boom while keeping
the hook block/overhaul ball at near ground level.
Once boom is fully retracted, raise block/ball up to boom
tip.
If block/ball rotates more than 90° during this procedure,
turn dead-end becket one revolution opposite the
direction that the block/ball rotates as the fall length
increases. Repeat as necessary until block/ball rotates
no more than 90°.
Using the Load Chart
NOTE: One of the most important tools of every Grove
crane is the
Load Chart Manual in the crane
operator's cab.
NOTE: Refer to Figure 4-210 for terms to know in
determining lifting capacities.
The Load Chart Manual contains crane lifting capacities in all
allowable lifting configurations and must be thoroughly
understood by the operator.
The left column is the load radius, which is the distance from
axis of crane rotation to load center of gravity. The top row
lists various boom lengths from fully retracted to fully
extended (with swingaway boom extension). The number at
the intersection of the left column and top row is the total load
limit for that load radius and boom length.
Another important section is the range diagram. The range
diagram shows operating radius and tip height that can be
achieved at a given boom length and angle. If the operator
knows radius and tip height required for a specific lift, the
angle and boom length can quickly be determined from the
range diagram. Or, if an operator knows boom length and
angle, they can quickly determine tip height and operating
radius.
CAUTION
Run engine at or near governed RPM during operation of
all crane functions.
CAUTION
Hoist Rope Damage Hazard!
Hoist rope that is not properly tensioned can cause rope
diving, which could result in rope damage.
Always properly tension the hoist rope by spooling as
much of the rope onto the hoist with as much load
available and allowable as indicated by the
Load Chart .