Hoist basics

Hoists are mechanical devices used for raising and lowering loads ranging from finished steel coils to individual work-in-process assemblies. They can stand alone for vertical lifting jobs, or can be paired with a crane or trolley system for both vertical and horizontal load movement.

The

• Electric (including wire rope and chain hoists)

• Air-driven

• Manual (including hand chain and ratchet lever hoists)

Which hoist is most appropriate for your application depends on a combination of factors, including the weight of your load and how high, how fast and how often you need it lifted.

With a range of capacities and applications, electric hoists are the dominant type of hoist used today. They range in capacity from an eighth of a ton to several hundred tons. Smaller hoists can be purchased off-the-shelf, while larger ones are usually custom engineered.

All are rated by duty cycle. “An electric motor can only run so long before it gets hot,” explains Dustin Nielson of JET Material Handling. For example, an electric hoist with a 25% duty cycle, he says, can be used continuously for 25% of an hour (15 minutes) before it needs to cool.

Electric hoists are available with single-speed, double-speed or variable-speed electric motors. Double- and variable-speed motors are more expensive than single-speed motors, says Mark Arthur of R&M Materials Handling, but they offer advantages.

Operators can begin lifting at a slow speed and then ease into a higher lifting speed, reducing shock on the system and preserving the life of the hoist. Operators can also slow the hoist at the end of a lift, allowing for more precise and gentle positioning of the load.

Because they are hard-wired to a power source, electric hoists have a dedicated location in a facility, unlike their more mobile manual counterparts.

Electric hoists are also available in two different lifting mediums: wire rope and chain.

Wire rope

When an operator presses the button and starts the motor on an electric wire rope hoist, the motor drives a set of gears, which then turn a grooved drum. The wire rope winds around the drum as it turns, lifting the load.

“Really heavy, really repetitive jobs require wire rope hoists,” says Arthur. Wire rope hoists are bigger than chain hoists, he says, and the bigger motors can handle larger loads. While these hoists can reach capacities of hundreds of tons, he says, the majority of the market is in the 5- and 10-ton models.

Wire rope hoists are usually too big and too expensive for small jobs, says Bob Smilak of Stahl CraneSystems, “but around 5 tons, wire rope becomes more cost-efficient.”

Wire rope hoists are used for such jobs as handling steel coils and assembling automotive equipment, says Smilak. Pricing for wire rope hoists varies based on the speed, height and capacity of the hoist. A basic wire rope hoist with a trolley, he says, costs anywhere from $4,000 to $60,000.

Chain

When an operator activates an electric chain hoist, the electric motor turns a set of gears, which then turn a lift wheel. Pockets in the lift wheel engage the links of the lift chain. The load is lifted as the chain rides over the wheel. Excess chain coming off the loose end of the wheel either dangles below the hoist or is collected in a chain container.

Chain hoists range in capacity from an eighth of a ton up to about 20 tons, says Ken Tilson of Columbus McKinnon, with most of the market at 5 tons and smaller. Chain hoists are slower than wire rope hoists of similar capacity, he says, but are also typically less expensive. They're also smaller, making them more maneuverable.

Electric chain hoists are used in manufacturing facilities for such jobs as loading raw materials into machining centers and lifting aircraft engines into place, says Tilson. They range in price from about $1,500 to $25,000.

Air-driven hoists, also known as pneumatic hoists, don't have electric motors, so they don't require electricity and don't overheat. This makes them essential for environments where heat from an electric motor could spark a fire or an explosion. It also makes them a good choice for highly repetitive assembly-line applications, says JET's Nielson, because they can be used continuously, without the cooling time electric hoists require.

The majority of pneumatic hoists are chain rather than wire rope, and they operate much like electric chain hoists. Because they aren't hard-wired to an electrical system, pneumatic hoists are a good option in facilities without a proper electrical supply.

Pneumatic hoists, however, have a limited capacity range. Anything larger than a 5-ton hoist, says Nielson, would require an enormous compressor to supply the necessary air power.

These hoists are also the most expensive type, he says, at nearly double the cost of a comparable electric hoist. Because of their high cost, pneumatic hoists are far less common than electric ones.

While powered hoists are often installed as permanent components of a materials handling system, slower manual hoists are small and mobile, and usually used for maintenance and other non-repetitive jobs.

Two styles of manual hoists are available: hand chain and ratchet lever.

Hand chain

A hand chain hoist has two chains: a lift chain that is attached to the load and a pull chain. As the operator pulls on the pull chain, the hoist's internal gearing raises and lowers the lift chain and provides the mechanical advantage for easing the lifting process. According to Arthur of R&M, raising a 1-ton load with a hand chain hoists requires just 54 pounds of effort.

While hand chain hoists can reach up to 70-ton capacities (even higher than electric chain hoists), the majority of the market is in the 1-ton to 5-ton range. According to Arthur, a typical 5-ton hand chain hoist with 10 feet of lift costs roughly $650.

Ratchet lever

Ratchet lever hoists can use either chain or wire rope as their lifting medium. They work much like hand chain hoists, but they use a lever instead of a pull chain to rotate the sprocket that activates the lifting mechanism.

Because the operator must be able to reach the relatively short lever, a ratchet lever hoist is best suited for low-lift situations, usually less than 5 feet. These hoists can pull horizontally as well as lift vertically. In fact, Nielson says “hoist” is a bit of a misnomer for these tools, which are used more commonly for pulling than for lifting.

Ratchet lever hoists range in capacity from a quarter ton to about 9 tons, says Nielson, but the most common capacities are the three-quarter and half ton. Small ratchet lever hoists range in price, he says, from $50 to $1,000.

Here's an introduction to the weight lifters of materials handling: electric, air-driven and manual hoists.