Importance

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Abstract

A crane block (FIG. 2) is provided for traveling along a central main fall symmetry line (78) defining vertical travel during movement of a hoist within a barge mounted crane. The crown block (50) is mounted to a crane boom (12) and includes a first row of relatively large diameter sheaves (54) in tandem with a second row of relatively small diameter sheaves (58). A movable block (76) is provided between the traveling block (74) and the crown block (50) and includes a third row of relatively small diameter sheaves (60) which are reeved together with the second row of sheaves. A traveling block (74) is provided with a fourth row of relatively large diameter sheaves (56) which are reeved together with the first row of sheaves (54). Sheaves in either the second (58) or third (60) rows are horizontally canted with respect to the main fall symmetry line (78) for vertical travel of the rope which is reeved between the rows. The movable block section ( 76) may be connected with the traveling block (74) for lifting relatively heavy loads over relatively small vertical travel distances. Conversely, movable block (76) may be two-blocked beneath the crown block (50) to enable the traveling block (74) to obtain extended travel distances at increased speed for relatively lighter loads without the need to re-reeve the main block.

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First Claim