Figure 12-4.-Crane radius measurement.
The primary advantage of the crawler crane over the
truck-mounted crane is that it is better suited for
continuous work in remote areas that are not readily
accessible to truck-mounted cranes because of terrain
conditions. Also, the crawler crane has steering with
positive traction that permits the crawler crane to travel
and turn without cutting up the work area or roadway.
The size of the crawler treads spreads the weight of
the crane over a large area. This feature gives the
crawler crane a low ground bearing pressure of 5 to 12
psi, giving the crane the versatility needed to travel over
soft terrain. When the crawler crane is climbing grades,
the maximum grade capability is 30 percent on firm, dry
material. The turning radius of the crawler crane is
about the length of the tracks, which travel 1/2 to 2 mph.
Because of the slow travel speed, it is not productive to
try to travel more than 1 mile. Additionally, traveling
the crane a long distance at one time causes extra wear
to the tracks. When travel distance exceeds 1 mile,
transport the crawler by tractor-trailer.
NOTE: Consult the operators manual for detailed in-
formation if required to track travel for more than 1 mile,
Steering of the crawler crane is performed by
engaging the steering lever in the direction you want the
crane to turn. Some models of crawler cranes have a
swing-travel jaw clutch that is controlled by one lever
Figure 12-5.Crawler-mounted crane quadrants of operation.