The initial development process of chain hoists

The United States produced chain hoists relatively early, with advanced technology and a wide variety of chain hoists, including differential hoists.

The use of chain lifting devices is quite common in the United States, and they are widely used in various installation and construction sites such as sand turning factories, grinding, repair workshops, car garages, and construction sites. Differential hoist is a type of chain lifting device with a simple structure and low cost, and its rated efficiency is about 30%. Equipped with one double groove upper pulley and one single groove lower pulley, connected by a series of circulating chains, used for lifting and manipulation. Its mechanical gain is obtained through two pulleys on a chain link groove, allowing the heavy object to be lifted or lowered simply, with most of the chains hinged by the large wheels. The difference in diameter between these two pulleys results in a small torque in this combination, where normal friction causes the weight in the suspended position to lock at any point. An additional force must be applied to lift the heavy lifting hook.

The cost of spiral gear hoists is higher than that of differential hoists, but the increased cost is compensated by increasing the mechanical rated efficiency by about 40%. Although the operation is slightly slower than the differential hoist, the operation is smoother. In recent years, most manufacturers no longer manufacture spiral gear hoists, but tend to produce spur gear units. This type of gourd is more efficient than spur gears with slightly higher manufacturing costs, and has been proven to be more economical to use in the long run.

The spur gear hoist is more effective than the differential hoist and spiral gear hoist, and this high-speed hoist is combined with a Weston self-excited brake. The spur gear hoist is an recognized standard for industrial applications, with a rated mechanical efficiency of about 80%. When the separated hand zipper and suspension chain run and lift on the hinge wheel connected to the wheel system, the brake is released through a one-way ratchet mechanism. When descending, to overcome the braking torque, the hand zipper must be continuously pulled in reverse.

There are various types of spur gear hoists, and in order to make them easy to carry and lightweight, a more compact structure is utilized. Light alloy and more rolling bearings are two standard models among them.

The double hook lifting device is a spur gear hoist with double hooks, which is operated simultaneously by a hand zipper and is suitable for lifting heavy objects that need to be hung at both ends. The total load lifted by this device is equal to the marked load capacity. The load can often be placed entirely on one hook or the other, or distributed in any proportion between the two hooks. The standard hook distance is 0.9~4.8, m