GB1146258A - Improvements in or relating to cranes - Google Patents

Abstract

1,146,258. Lifting tongs. KERMA CORP. 21 July, 1967 [25 July, 1966], No. 33777/67. Heading B8H. An overhead bridge crane A comprises a vertically movable column D with load-engaging tongs E. The column D is raised and lowered by rotation of a drum 40, cables 42, 43 attached thereto passing round sheaves 44, 45 rotatably supported in vertically movable members connected by means including an equalizing lever 46 to a member 47 supported for limited vertical movement in a guideway 48 in the column D. The cables 42, 43 extend upward to trolley 14 where they are connected to a pair of stabilizers (49), Fig. 1 (not shown). The tongs E may be rotated about a vertical axis by a motor 102 on the column D driving a shaft 108 through a speed reducer 106. The tongs E may be opened and closed by vertical movement of an actuator rod 68 mounted on a thrust bearing 72 in a crosshead 71 pivotable about bosses 75. The rod 68 is raised or lowered by rotation of a drum 41 carrying cables 94, 95 which pass around sheaves 86, 88 and have their opposite ends wound on and connected to the drum 40. The crosshead 71 supports sheaves 76, 77 carrying slings 78, 80 which are connected at one end to slidable sheave blocks 82, 84 respectively supporting the sheaves 86, 88. The blocks 82, 84 can slide in guideways 89, 90. The other end of the slings 78, 80 are connected to the sliding frame 47 at 91, 92. In removing an ingot (not shown) from a soaking pit all cables 42, 43, 94, 95 contribute to the support of the column D. If cables 42, 43 break the member 47 would move downwards until its lower end engages the framework of the column D whereupon the entire weight is transferred to the cables 94, 95 without the tongs E opening and dropping the load.