GB709438A - Improvements in automatic lifting dogs - Google Patents

Abstract

709,438. Lifting dogs with automatic control. BRITISH ELECTRICAL REPAIRS, Ltd. May 16, 1952 [June 8, 1951], No. 13609/51. Class 78 (4) Whether a pin g on an arm c of the lifting dog illustrated is trapped in a recess f in a locking bar a to prevent the dog closing after it has been opened is determined by the position of a ratchet wheel h turned about its pivot on the locking bar a each time the dog is raised. When the dog is open the pin g enters the end j of the recess f. When the dog is subsequently raised the pin engages one of four projections n on the ratchet wheel to turn it through 90 degrees. The ratchet wheel includes two surfaces k: if. when the dog is raised, the pin g engages one of these it is thrown out of the recess f as shown in Fig. 3. If, however, the pin g does not engage surface k it is allowed to enter the end m of the recess f to lock the dog in its open position as shown in Fig. 2. A spring biased pawl i engages the projections n to prevent reverse rotation of the ratchet wheel. Two such dogs may be carried by suitable lifting tackle and work in unison. Each arm b and c may comprise a pair of spaced parallel links riveted or otherwise secured together and between 'which the locking bar a and pin g are mounted.