The chain hoist is a hand-operated hoist that is easy to use and easy to carry. It is suitable for short-distance lifting of small equipment and heavy objects, temporary suspension, and adjustment when hoisting large components. The lifting weight is generally in the range of 5 to 200 kN. The chain hoist has a compact structure, small hand pull force, and stable use, which is easier to grasp than other cranes.
The chain hoist consists of a sprocket, a chain, a transmission machine, a lifting chain and hooks. Among them, the mechanical transmission part can be divided into two types: worm gear drive and gear drive. The gear-driven chain hoist has a sheet-shaped chain hoist, which has a small lifting weight of 2.5 to 10 kN, and a lifting speed of 2.24 to 0.65 m/s when lifting. The other type is a planetary gear chain hoist. It can weigh up to 200kN.
When lifting a heavy object, the chain pulls the key wheel in a clockwise direction, and the sprocket moves inward along the thread on the disc sleeve. The ratchet wheel and the friction plate are pressed against the sprocket shaft, the ratchet ring can only rotate clockwise, and the gear at the right end of the sprocket drives the gear to mesh with the fixed ring, so that the gear rotates clockwise along the sprocket axis. Drive the driving mechanism and the lifting sprocket to rotate, so that the lifting chain rises. When the chain is not pulled, the weight is self-locking caused by its own weight and the pawl prevents the ratchet ring from rotating counterclockwise and stops in the air.
Conversely, when the weight is loosened, the chain is rotated to rotate the sprocket counterclockwise, the chain moves outward along the thread on the disc sleeve, and the ratchet friction plate and the disc sleeve are separated, and the sprocket shaft is at the right end. The gear and the driving gear mesh with the fixed gear to rotate the gear counterclockwise around the chain shaft, and at the same time drive the driving mechanism and the lifting sprocket to rotate, so that the lifting chain is lowered.
When the chain is not pulled, when the sprocket stops rotating, the lifting sprocket transmission mechanism also continues to rotate in the counterclockwise direction, so that the disc friction plate and the ratchet ring are pressed against each other to generate frictional force, and the ratchet ring is subjected to friction. The pawl prevents the counterclockwise rotation, so that the friction acts on the thread to create a self-locking force that stops the weight in the air.