GB191102766A - Improvements in Lifting Dogs. - Google Patents

Abstract

2766. Parry, D. Feb. 3. Lifting-dogs, of the type in which the engaging ends of tong-like arms are held open by automatic catch devices which come into action after a lifted load has been released, and are disengaged to free the arms when the apparatus rests on the article to be lifted, are constructed with special automatic catch devices. Fig. 2 shows a lifting-dog with the arms released from the catches. The tong-like arms a are pivoted in a pair of frame members f which also form guides for sliding members n carrying pivoted pawls q and connected to the ring c of the lifting-tackle. After the dogs have been released from a deposited load, the lifting - tackle is slackened further, thereby causing the pawls to move downwards and outwards over the hooks g until the hooks register with the inclined slots s in the pawls. The pawls then fall by gravity and engage the hooks, thus maintaining the arms in the open position when the arms are raised. When the tongs rest on the article to be lifted, the lifting-tackle is slackened still further until the pawls slide off and pass below the hooks. When the tackle is wound up again, the upper edges of the pawls engage the hooks and are rotated through a half-revolution thereby passing the hooks without locking the arms.