Broderson RT-400-A, Operation And Maintenance Manual

Page: 37 / 93

2-23
CAUTION
The ON OUTRIGGERS capacities of this crane are based on all outriggers being
FULLY DEPLOYED to a FIRM surface with no load on the tires. The crane may tip at
less than capacity loads if operated in the following manner:
A. Outriggers only partially deployed or tires carrying some load.
B. Crane operated on a hill or sloping surface. Crane will tip at less than rated capacity if
crane is not level.
C. Outriggers extended to a surface that appears to be firm, but is unable to support the
outrigger pad at full rated loads. Examples of this type of surface are:
1. Thin or cracked blacktop or concrete.
2. Dirt that appears dry and firm on top but is moist or unpacked beneath the
surface.
3. Dirt with a frozen but thin crust.
CAPACITY EXAMPLE (Also See Boom Extension Capacity Example Page 2- 29 )
Refer to the RT-400 capacity chart on the preceding page. A load 6’ X 6’ X 6’ (1.5 m x1.5 m
x 1.5 m) and weighing 12,700 pounds (5750 kg) is to be lifted to a new location. The load is
on a roof 64’ (20 m) high. The center of the load is 24’ (7 m) from the center of rotation of the
crane.
The chart shows that 10,000 pounds (4500 kg) is the maximum load on one-part line, so the
sheave block is required. The chart also shows the weight of the standard sheave block to
be 490 pounds (223 kg). The rigger indicates that two slings are required, weighing a total of
50 pounds (23kg). The total load is 10,000 + 490 + 50 = 10,540 lbs (4500 + 223 + 23
=4746kg).
The 360° ROTATION, ON RUBBER column of the chart allows lifting up to 17,000 pounds
(7700 kg) at a 8-foot (2.4 m) load radius. However, this radius is less than the distance from
the center of rotation to the center of the load, so the load cannot be lifted in this
configuration. This lift will require the ON OUTRIGGERS columns to be used. Outriggers
should always be used whenever possible.
The boom will need to be fully extended to reach the desired height. ON OUTRIGGERS
360° with a fully extended boom at a 24’ (7 m) load radius, the capacity is 17,800 pounds
(8000 kg) which is more than the total load. The load can be lifted over the front on
outriggers or over the side on outriggers. If possible, position the crane to lift the load over
the front with the outriggers deployed. This is the best position for stability.
NOTICE
As the boom is loaded, deflection of the boom, tires, etc. will increase the load radius.
Be conservative in your capacity estimate.