How does a chain hoist work？

The hand chain hoist is an upgraded version of the pulley, completely inherited the advantages of the pulley, manual hoist saving is the use of the principle of mechanics, through the human power to drive the hand chain so as to produce traction, the use of gear transmission mode, the pinion drives the large gears, will be enlarged to transfer the torque, in order to drive the lifting chain to complete the heavy lifting and hoisting.

Principle of operation

Chain fall hoist up to lift the goods, pull down the hand chain to make the hand chain wheel for clockwise rotation, the hand chain wheel rotation, the friction plate ratchet, brake pressure into one common rotation, so the hand chain wheel drive the transmission gear transmission, so that lifting the chain wheel drive chain so that the goods are smoothly uplifted, the use of ratchet friction plate one-way brake, in the load can be automatically braked, the ratchet pawl in the spring under the action of the bite with the gears, to ensure that The pawl bites with the gear under the action of spring to ensure that the cargo stays in any position in the air and will not fall down by itself.

When descending, pull down another hand chain to make the hand sprocket rotate counterclockwise, then the pawl releases the ratchet wheel, and under the action of the lower hook and other self-weight, it can be descended smoothly, and when the hand chain stops pulling, the brake resumes its braking function immediately, so that the goods can be stopped at any position.

Structure of chain hoist accessories

Although the chain block hoist looks small in size, it is composed of more than 70 parts, mainly by the lifting sprocket, hand chain, transmission gear, lifting chain, long axis, brake, ratchet wheel, hand sprocket and the upper and lower hooks and other major accessories, details can be referred to the following structure diagram:

Chain hoist machine limit strength standard

(1) The Chinese machinery industry standard JB/T 7334 stipulates that: by releasing the brake to put the tail ring device in working condition, the hand chain hoist should be able to reliably withstand a static tensile load of 2.5 times the rated lifting capacity without breakage.

(2) The European EN standard EN 13157 stipulates that the chain end connection fixture should be able to withstand a static tensile load of 4 times the rated lifting capacity of the chain without breakage.

(3) The American standard ASME B30.16 provides for over-travel restraints: the lifting chain shall be restrained in the fully slipped position before it slips completely out of the hoist. The restraint shall be such that the unloaded hoist is capable of withstanding a descending hand chain force equal to 2 times the pull required to lift the rated load or, with the rated load on the hoist, a hand chain force equal to the pull required to lift the rated load. The comparison shows that the requirements in China and Europe are different: 2.5 times in China and 4 times in the EU.