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TRIPLE-PAWL RATCHET-TYPE MECHANISM OF A HOIST

A counterclockwise torque is applied about fixed axis A to ratchet wheel 1 to hoist load Q. Pawls 2, 3 and 4 turn about axes B, C and D and separately engage the teeth of wheel 1, preventing rotation in the reverse direction and dropping of load Q. The pawls are of different length or their axes of rotation are so located that if pawl 2 engages the face of a tooth, pawl 3 is one-third pitch beyond…