Manitowoc Grove GRT8120, Operator'S Manual

Page: 307 / 448

Grove
Published 3-22-2021, Control # 702-02
4-177
GRT8120 OPERATOR MANUAL OPERATING PROCEDURES
4
A lifting diagram is included for over-side, over-rear, and
over-front lifting areas. The lifting area diagram shows
locations of the outrigger jack cylinders in full extended
position are used to mark lifting area boundaries.
Another section contains notes for lifting capacities. Be sure
to read and understand all notes concerning lifting
capacities.
Capacity reductions for wind speed are also included in the
Load Chart Manual .
The load chart also gives weight reductions for Grove load
handling devices such as hook blocks, overhaul balls, boom
extension sections, etc., which must be considered as part of
the load. Weight of any other load handling devices such as
chains, slings, or spreader bars must also be added to the
weight of the load.
NOTE: Information in the following paragraph is an
example only of how to compute a lift. Numbers
may not match load chart in the crane cab.
Example: A concrete beam weighing 2268 kg (5000 lb)
needs to be lifted to a height of 9.1 m (30 ft) at a radius of
15.2 m (50 ft) (maximum). The range diagram indicates the
boom must be extended to 18.9 m (62 ft) to reach a height of
9.1 m (30 ft) at a radius of 15.2 m (50 ft).
First check the crane for load handling devices. In our
example, the crane is equipped with a auxiliary boom nose
(rooster sheave) and a five ton overhaul ball. The rooster
sheave is 50 kg (110 lb), and the overhaul ball is 78 kg
(172 lb) for a total of 128 kg (282 lb). The lift requires slings
and spreader bars weighing 159 kg (350 lb) which makes
the total weight for the load handling devices 286 kg (632 lb).
A check of the load chart for a 15.2 m (50 ft) radius and
19.5 m (64 ft) of boom length shows a capacity of 3601 kg
(7940 lb) on outriggers over-front and 2254 kg (4970 lb) on
outriggers 360 degrees.
Subtract load handling weight of 632 lb from load capacity of
3601 kg (7940 lb) and 2254 kg (4970 lb). The result is a
weight capacity of 3315 kg (7308 lb) over-the-front and
1968 kg (4338 lb) for 360 degrees.
We are restricted in making the lift over-front only, with a
boom angle of about 29 degrees.
FIGURE 4-210
OPERATING RADIUS
HORIZONTAL
BOOM ANGLE
MAIN
BO
OM
LEN
GTH
AXIS OF ROTATION
4605
TERMS TO KNOW