Telescopic Truck Cranes
Telescopic Truck Cranes are purpose built trucks with a telescopic boom mounted on the back. Usually there is a cab for driving the truck on the road, and a cab for controlling the crane at the back. They are sometimes referred to as cherry pickers, zoom boom and hydraulic cranes.
Telescopic truck cranes have the advantage of being able to be moved about quickly between job sites, however they lack the rough terrain capability of a crawler once on a site.
The weight of the telescopic truck crane has always limited boom length and the load weight it can lift, however this is always being improved with later lighter weight designs. Telescopic truck cranes are made to work with up to 850 ton capacity and a boom length of up to 197 feet in length.
The boom itself is made up of a series of rectangular to trapezoidal cross sectioned segments fitting into each other. The largest section call the base is at the bottom of the crane, and the other sections fit inside it. The fly section is the smallest cross section located at the top of the boom. In between there can be one or more sections called mid sections, labelled first, second, third and etc. At the end of the fly section is the boom head which carries the upper load and lead sheaves.