GB560033A - Improvements in or relating to lifting appliances - Google Patents

Abstract

560,033. Lifting - dogs. ENGLISH STEEL CORPORATION, Ltd., and BROCKLEHURST, R. W. Aug. 19, 1942, No. 11638. [Class 78 (iv)] A lifting dog, grab, &c., of the type comprising relatively moving jaws tending to assume a closed position on being lifted is provided with means whereby the operator can either lock the jaws in an open position and lift and lower them in that position, or can release such lock, solely by manipulation of the lifting tackle. The device consists of two telescoping members 16, 34 pivoted respectively at 18 and 30 to the grab arms 10 which are each fulcrumed at 11 to the side plates 12 of a framework 15. To lugs 19 extending upward from the member 16 is pivoted a pawl 21 biassed downward by a spring 23 acting through a rocker arm 24 bearing on a pin 25 extending forward from the pawl, all these parts being carried by the member 16. The member 34 is of reduced diameter at 32 to form two spaced apart shoulders at 33 and 35, and between these shoulders is located a loose sleeve 36 slidable with friction inside the member 16. The sleeve is shorter than the spacing between the shoulders 33, 35 and a slot 38 is provided in the member 16 to permit the nose of the pawl 21 to enter and abut against the shoulder 33. A flag mounted on an arm fixed on the pivot spindle 26 of therocker 24 comes into view at a window 39 in each plate 12 when the pawl 21 is up, In operation, the grab is lowered till the frame base 15 rests on the load, when, on further forward feeding of the suspension cable, the weight of the arms 10 allows their lower gripping jaws to open and the pawl 21 eventually to fall into engagement with the shoulder 33, this condition being indicated to the operator by the disappearance of the flag. The grab can then be raised in open-jaw configuration, and when it is desired to lift a load it is lowered thereon and the cables slackened till the jaws, in opening still further, cause the sleeve 36 to be dragged along and to raise the pawl nose, this condition being indicated by the reappearance of the flag. On now commencing hauling the sleeve 36 remains stationary, holding up the pawl 21, till the shoulder 33 abuts against it and slides it inward, the pawl nose passing smoothly on to the enlarged main body of the member 34 and allowing the jaws to grip the load. The inner end of the sleeve 36 is bevelled or rounded to prevent its acting as an abutment to the pawl 21. In a modification a second abutment is provided, permitting the actuation of the grab in two stages.