A hoist is a machine that is used to lift, suspend, move and lower a load by means of a lift wheel or a lift drum which is attached to a hook. Different lifting mediums such as wire, rope, fiber or chain is looped around the drum or wheel and the system can be manual or electrically operated. The most popular type of hoist used worldwide is the electric chain hoist which is used in a wide variety of applications, mostly in the manufacturing and construction industries.
With an I beam chain hoist, the load is lifted by a pulley attached to the hoist. Numerous pulleys can be found in a chain hoist, from small to large. In order to raise a load, a pulling force has to be applied to the chain. A large pulley will draw in more chain than required by the smaller side which facilitates the start of the lifting procedure.
How Does A Chain Hoist Work
The workings of a chain hoist uses the following:
-Gears to multiply a force.
-An operator to control the start, lift, suspension, moving and lowering of the load.
-A light chain to pull on one side which turns the gear mechanism to move the chain pulley.
-As the pulley turns it raises the heavy chain with a hook on the end attached to the load.
-By pulling the lighter chain loop, the hoist increases the force being applied by the heavy chain caused by the gear ratios and the load is lifted.
An electric hoist has a motorized trolley which is attached to an overhead rail or beam. Standard beams are generally classified by weight and size per foot. When selecting a motorized trolley for a standard beam, the following information should be considered:
-Height of the beam
-Lower flange width or size
-Adjustable range of the trolley
Trolleys are available that can be adjusted to fit on different beam sizes and most standard trolley wheels have crowned or tapered wheel treads to operate effectively on a standard beam. It is important to check that the selected trolley has the same or greater capacity than the selected hoist.
Types Of Beams
Flat Flanged Beams or Wide Flange Beams are similar to American Standard Beams classified by weight and size per foot. The use of wide flange beams has increased significantly in recent years and is used more frequently than the American Standard Beams. This has prompted trolley manufacturers to increase the beam adjustability ranges of their trolleys to accommodate this change to standardized universal type trolleys. Universal type trolleys are designed with wheels that are capable of riding on either flat or sloped beam flanges.
Standard electric hoists are easily obtained from local manufacturers, however, more specialized hoists are usually obtained through crane builders or material handling specialists. They are commonly used in industrial plants for lifting, lowering and transporting applications throughout a facility and the positioning of components in assembly or process operations.