How Does a Chain Hoist Work Mathematically?

[g.bashyam]

Can anyone explain the mechanics of a chain hoist and its mechanical advantage, in mathematical terms,?
thank you
Bashyam

 

[Quinzio]

It's a force multiplier.
You look the number of turns of the chain and this number multiplies the original force.

 

[DickL]

There are several different types of chain hoists. The most common type seen today has an input chain loop that drives the output (lifting) chain via a step down gear unit inside the hoist's housing. I think the gear unit is a planetary one.

 

[JohnMorriss]

The simpest form of chain hoist consists of a pair of discs of different diameters, locked together with their centres aligned. The two gears on the pedal crank of a ten-speed bike are what you should picture. The gear "teeth" are designed to mate without any chance of slipping with the chain being used.

The chain comes from somewhere, pases over one of the gears from (say) left to right, drops down and around an idler wheel. From there it goes up and over the SECOND gear, again from left to right, and then goes off somewhere. The cheapest way is to connect the two "somewhere" ends of the chain together.

Suppose the larger gear as T teeth, and the smaller has t teeth. If you pull in enough chain to rotate the paired gears 1 revolution clockwise, then you have removed T links of chain from the hanging loop, and added t links feeding off the smaller gear into the loop. So the loop gets shorter by ( T - t ) links, and since the loop goes down to the idler and then back up, the idler rises by ( T - t ) / 2 links.

So you exert a force through a distance of T links, and get an output through ( T - t ) / 2 links.

If the two gears have 24 and 20 teeth, for example, you pull in 24 links of chain to raise the load 2 links. 1 / 12 the distance means 12 times the force

 

[PJC01]

Sure, I'd be happy to explain the mechanics of a chain hoist. A chain hoist is a type of lifting device that uses a chain and pulley system to lift and lower heavy objects. The basic components of a chain hoist include a lifting hook, a chain, a pulley, and a hand chain or lever for operating the hoist.

The mechanical advantage of a chain hoist refers to the ratio of the load lifted to the force applied. In other words, it is a measure of how much easier it is to lift a heavy object using a chain hoist compared to lifting it by hand. The mechanical advantage can be calculated using the following formula:

Mechanical Advantage = Load / Effort

Where:
- Load refers to the weight of the object being lifted
- Effort refers to the force applied to the hand chain or lever to lift the load

For example, if the load being lifted is 1000 pounds and the effort applied to the hand chain is 100 pounds, then the mechanical advantage of the chain hoist would be 1000/100 = 10. This means that the hoist is able to lift the load 10 times easier than lifting it by hand.

The mechanical advantage of a chain hoist can also be affected by the number and arrangement of pulleys in the hoist. The more pulleys, the greater the mechanical advantage. This is because each pulley reduces the amount of effort needed to lift the load.

In addition to the mechanical advantage, the chain hoist also utilizes the principles of leverage and tension to lift heavy objects. As the hand chain or lever is pulled, tension is created in the chain, which is then transferred to the pulley and ultimately to the load. This tension, along with the mechanical advantage, allows the hoist to lift heavy objects with relatively little effort.

I hope this explanation helps to clarify the mechanics of a chain hoist and the concept of mechanical advantage. Please let me know if you have any further questions.