A travelling block system that can be changed quickly from a four support line system to a two support line system, which comprises a travelling block having two sheaves, and a single sheave block with hook, attached to the crown of a boom. The two sheave travelling blocks comprise a frame with two parallel spaced plates serving as inner sheave plates, two sheaves on the outside of the inner sheave plates, and two outer sheave plates. The sheave plates are firmly bolted to the frame, and appropriate sheave pins are supplied through each pair of outer and inner sheave plates. Two guard strips are provided which are removably attached around the periphery of the outer and inner sheave plates so as to completely contain the cable around the sheave on sides and bottom of the sheaves.
A hoist for lifting appliances, and more specifically a block-and-pulley arrangement, or a block-and-tackle arrangement. A plurality of pulleys is arranged between two pulley-housing parts. Each of said plurality of pulleys is supported by its own relatively short shaft. Half of the pulley-supporting shafts is supported in the upper pulley-housing part, and the other half of the pulleys is supported by partitions in the lower pulley-housing part. Pairs of partitions in the upper pulley-housing part and pairs of partitions in the lower pulley-housing part are interleaving or out of registry. The load-supporting hook has a shaft which projects vertically through both pulley-housing parts by a bearing, so that it is rotatable relative to the upper pulley-housing part. A load supporting cross-member is arranged in transverse relation to the hook-bearing shaft and the latter projects through its center. The cross-member is supported by the lower pulley-housing by the intermediary of a bearing, so that the cross-member is rotatable relative to the lower pulley-housing. This arrangement of parts ensures safe operation of the hoist, or the pulley-and-tackle arrangement, even if any of the constituent parts of the latter should break or fail.
In order to increase the operational safety and to reduce the rope wear, hoisting/lowering apparatus comprise one or a combination of novel features: an adaptor (3) is provided in order to allow the attachment of accessories (50), preferably by insertion. Possible accessories are e.g. holders having a loop for the attachment of hooks, and single or multiple blocks for the formation of lifting blocks. Substantially, the adaptor is formed of a number of slot-shaped recesses which are transversely traversed by rod-shaped retaining elements (11, 9). One of said retaining elements (9) is displaceably mounted in order to allow the attachment resp. detachment of an accessory (50). Another measure is to provide a rope stop (102) on the traction side. The rope (103) runs through the rope stop (102) and drives a knurled wheel (110). At a given rope speed, the wheel is coupled to a pivotable brake appendix (118) by means of a centrifugal coupling (113, 115). The rope (103) is then squeezed and blocked between the appendix (118) and a counterpart (108). A third measure consists in providing guiding rolls (36, 37) in order to ensure a spiral-shaped travel of the rope (103) which is free of crossings.
A support for boom end sheaves for lifting and/or handling machines, carrying at least a first sheave which receives a flexible rope, particularly a lifting cable, extending from the boom, is characterized in that it carries a pulley-block mounted on a lever which is swingingly carried by the support.
The device enables a switch from the pulley blocks being rigged with one strand to the pulley blocks being rigged with two strands and vice versa. The jib tip has a pulley moveable along its axle between a central position, when the blocks are rigged with one strand, and a lateral position, when the blocks are rigged with two strands. The lifting block, with housing of symmetric shape, comprises a pulley and retractable guide means for the lifting cable. When the blocks are rigged for two strands, the end of the cable is connected to a point of attachment situated on the jib tip, on the opposite side to the lateral position of the pulley. When the blocks are rigged with one strand, the end of the cable is connected to a point of attachment situated on the pulley block. This device for changing the rigging of the blocks applies mainly to luffing cranes.
A field adjustable block for use with a bridge crane having a rotating cylindrical drum for rope. The block includes a cylindrical center pin having a key way recess parallel to an axis of the center pin. An inner side plate has an opening therethrough and an extending key receivable in the key way recess to prevent rotation of the inner side plate. Multiple sheaves are receivable over the center pin. At least one toroidal spacer is receivable over the center pin. A lock washer has an inwardly extending key receivable in the key way recess of the center pin and has a plurality of radially extending tabs. A nut has at least one notch to receive one of the extending tabs therein. An outer side plate is removably attached to the inner side plate by fasteners.
