GB207712A - Improvements relating to grabs, excavators and like apparatus - Google Patents

Abstract

207,712. Richardson, H. Dec. 23, 1922. Grab-buckets. - Relates to grabs in which a member 3 sliding relatively to the grab head is locked, when the grab is closed, to a lower member 4 connected with the buckets. For releasing the buckets from the member 3 in midair, a tripping-device for releasing the lock is operated by relative movement between the member 3 and the grab head. As shown, the grab is similar to that described in Specification 179,663. Angle levers 11 with hooked ends pivoted on the lower member 4 pass through an aperture in the member 3 and are held apart by a discharging lever 14, seen in end view, so as to lock the parts 3, 4 together, but the member 4 now forms the main cross-bar of the grab, and the member 3 forms a lower sheave-block cooperating with a block 1 on the grab head. The block 3 is provided with vertical guide-bars 10 which slide in guides 7 of H-section fixed to the cross-bar 4, these guides 7 sliding on bars 8 depending from the grab head. A weight 20 slides on a guide 21 secured to one of the bars 8, and rests on one end of a lever 18, of which the shorter weighted end 17 bears under the discharging lever 14. The lever 18 may be operated by a chain 19 for hand-dumping, or by the sliding weight 20 when the closed grab is lowered to the ground, as described in the prior Specification. The tripping device for releasing the lock in mid-air comprises a lever 22 pivoted on the cross-bar 4 at 23, and a pawl 24 on a bracket 25 secured to one of the guide-bars 8 on the grab head. For discharging, the grab is suspended from an opening rope secured to the grab head at 26, and on paying out the lifting rope, the block 3 and cross-bar fall, the lever 23 is caught by the pawl 24 and engages the end 17 of lever 18 so as to operate the discharging lever 14. The grab may be closed by paying out the lifting rope until the block 3 engages the cross-bar 4 and then hauling in. The sliding weight 20 may be dispensed with if discharging by dumping is not required. In a modification, shown in side elevation in Fig. 2, in which there is no provision for discharging by dumping or by hand, the lever 18 is omitted and the end of the discharging lever is tripped by engagement with a stirrup 28 pivotally suspended from a bracket 27 on the grab-bead.