GB291913A - Improvements in and relating to grabs - Google Patents

Abstract

291,913. Barnard, D. J. March 28, 1927. Grab-buckets.-The trip-mechanism for single-chain grabs described in Specification 225,367 is modified so as to avoid the use of a button on the lifting chain. The sliding member 16 in the thimble 15 mounted between the upper block plates 12 is provided with a cross-bar 23 adapted to be gripped between two pairs of hooks 24 which may be formed on or secured to the spreader arms 9. The members 15, 16 are slotted and co-operate as before with arms 21 of suspension hooks 17 provided with pins 18 moving in slots 19 in lugs on the thimble 15. The member 16, 23 is cushioned by spring-controlled pins 29 on the grab-head. The buckets 1, 2 and the two arms 9 are provided with interengaging teeth at 26 and at 25. When the closed grab is being lifted on the chain 28, Fig. 1, the sliding member 16 is in its lower position, and the bar 23 is clear of the gripping hooks 24. When the hooks 17 are supported on the ring 27, Fig. 3, and the chain is payed out, the gripping hooks 24 rest on the top of the bar 23 until, at the end of the opening movement of the buckets, the jaws 24 open widely enough to engage over the bar 23. On hauling in the chain, the jaws 24 grip the bar 23, the buckets are held open and the hooks 17 are lifted from the ring 27 and fall clear so that the open grab can be lowered to the ground. When the buckets rest upon the ground, the jaws 24 become free, the bar 23 drops and the hooks 17 come into position to engage the ring 27 when the grab is raised.