FAQ >> Column Crane

Column Crane

Fig. 51 represents a jib crane, of essentially the same construction as that described on page 115, but arranged to revolve around a fixed center column within the mast, the column being utilized for supporting the floor above. This type of crane is built of any desired capacity from r ton to io tons, although for capacities above 5 tons it is best if possible to arrange the cranes independently of the supporting columns.

The mast consists of two wrought iron channel beams, securely fitted to heavy castings at top and bottom, each of which latter contains horizontal rollers, traveling upon turned paths on the center column, the lower or foot casting being provided also with vertical rollers, traveling upon a circular path around the foot of the column. The vertical rollers carry the weight of the crane and load, while the horizontal thrust at top and bottom is received upon the horizontal rollers. Thus arranged the rotation of the crane is as smooth and easy as that of a crane turning upon ointles in the usual way.

All of the other details of this crane being precisely similar to those described on pages 115 to 117, reference is made to that description, which will, therefore, not be repeated here. This type of crane is designed especially for use in buildings where an upper floor is supported upon columns which cannot be removed, and around which it is therefore desirable that the cranes should rotate. Thus arranged they have all the convenience and applicability of ordinary jib cranes.

Estimates will be furnished on receipt of information as to the maximum load to be lifted, height from floor to ceiling, effective radius desired, and distance from center to center of column, where they are so near as to limit the sweep of the crane. By limiting the latter to less than an entire revolution, the jib may be lengthened so as to extend beyond the adjacent column.

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