There are lots of methods used in moving heavy loads but one of the oldest used is a hoist. Hoists come in many guises and can be used to successfully and safely move heavy items, however, they do need to be set up correctly and used properly. If set up and used correctly, a chain hoist is one of the easiest and most efficient ways of lifting a load.
A chain hoist is operated by hand. An operator will pull down on one of the chain loops on one side of the chain. This will turn a pulley mechanism inside the chain hoist housing. When this pulley turns, it will lift up the end of the other chain which usually has a hook on the end. By pulling down on one chain, the manual hoist is actually able to increase the mechanical work that is being done. This is caused by the gear ratio inside the manual chain hoist.
Inside the chain hoist housing are two gears. One is smaller than the other. Most chain hoists use a 20cm and 25cm gear. The two gears are attached, so when one moves, the other moves. The chain is looped over the smaller gear, and then hangs down in a loop (the loop you pull on). The chain then continues on over the larger gear and down to a point or another loop, depending on the type of hoist you are using. The operator pulls on the section of chain which is looped over the smaller gear.
When someone pulls down the chain as explained in Section 1, the smaller gear will turn. However, since it is smaller in size, it turns faster than the larger gear. It makes more rotations than the larger gear in a.... Click here to continue