GB277744A - Improvements in and relating to grabs, excavators and the like - Google Patents

Abstract

277,744. Smith, W. June 22, 1926. Grab-buckets.-Relates to grabs of the type in which a sliding member 3 mounted between telescopic guides carries means for automatically locking or unlocking it to or from the hinge cross-head, and may have means for automatically tipping the buckets. The invention is shown as applied to the grab described in Specification 244,533. To avoid the need of a button on the lifting chain 31 in removing the open grab from the suspension ring 46, the L-shaped lever or levers 38 pivoted on the grab head 2 for engagement with the inside top edge of the conical ring are disengaged from the ring by means of a rod or rods 41, which is pivoted on the lower arm of each lever, slides in the grab head and is held downwards by a weight 43 or spring 44, or by both. With the buckets closed, the lower sheave block 3 cannot rise in its guides above the position shown, but after the lower cross beam 4 has been released from the sheave block 3 by the trip mechanism and the buckets have fallen open, the block 3 can be raised further by the lifting chain 31 until its bracket 45 lifts the rod or rods 41 and throws the lever or levers 38 inwards clear of the ring. So long as the weight of the open grab remains on the chain 31 the levers are held in this position and can be lowered through the ring, but when the buckets are again closed, the levers are free to engage the suspension ring. In a modification, the hooked ends of the levers engage an external groove in a suspended block and the lower arms of the levers are turned inwards and connected with a single rod 41. Reference has been directed by the Comptroller to Specification 217,636.