A torque is applied in the clockwise direction (when looking downward) about fixed axis A to ratchet wheel 1 to hoist load Q. Load Q is suspended from flexible link 4 which is wound around pulley 5 and runs over pulley 6. Pulley 5 is rigidly attached to (or integral with) wheel 1, and pulley 6 rotates about fixed axis D. Teeth a are on the top end face of wheel 1 and are engaged by pawl 2 which turns about fixed axis B and is held against wheel 1 by spring 3. Reverse rotation of ratchet wheel 1 (and dropping of load Q) is prevented by pawl 2.
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