Chain block, also known as chain block, uses hand to pull the zipper bar to provide power, so as to drive the sprocket to rotate, so as to lift and lower the lifting chain, so as to realize the lifting and lowering of heavy objects. Each time the chain is pulled, the heavy objects will be temporarily suspended in the air without falling. This is because the braking system plays a role, that is, the friction plate is squeezed to increase the friction, Thus, the heavy objects do not fall in the air;