By Mark W. Schieber, President of International Air Tool & Industrial Supply Co. a San Diego, CA based distributor of pneumatic tools, air hoists, and diaphragm pumps.
What are the determining factors when selecting the right hoist for a job? How do you decide whether to choose a pneumatic hoist over an electric one, or to go budget and use a manual chain fall instead? What about brand name and price, who makes the best hoist for the money? In the following article we will discuss the basics of hoist construction and use in an effort to demystify the selection process. Let’s begin by defining the types of hoists available and discuss how they operate.
What is a Hoist?
A hoist is a material handling device used to lift or lower a load typically too heavy to be safely picked up by a person. Hoists utilize chains and gears to eliminate the need for manual lifting and allow for the handling of heavy object. Hoists feature chain or wire rope that is spooled around a drum. The drum is connected to gears which are either driven manually or by an electric or pneumatic motor. Manual chain hoists require the operator to physically pull the control chain, while electric and pneumatic models feature pendant controls that activate their respective motor. As the load chain winds around or unravels from the drum, the load is moved either up or down. At the end of the chain or wire rope is the load hook (also called the bottom or lower hook). Loads can be connected directly to the load hook or to an accessory such as a sling located in between the load hook and the load. Hoists are typically mounted on an I-beam or jib crane using either a hook or a trolley. We will discuss the different mounting options later.
Types of Hoists:
Manual Hoists (aka Chain Falls) – Manual hoists are designed for occasional, non-production lifting where fast lifting is not required. Manual hoists feature two different chains; one to lift and lower the load (control or hand chain) and one to support the load (load chain). Manual hoists are operated by manually raising or lowering the control chain using a “hand over hand” motion to lift or lower the load. The pulling action of the hand chain turns a series of gears and sprockets located inside the hoist, which results in the raising or lowering of the load chain and hence the load itself. Manual hoists (chain falls) are available in 1/2 ton to 25 ton capacities and are ideal for use in rigging, maintenance, construction, shipbuilding, and automotive applications. The length of the load chain (the amount of lift) and the length of the hand chain (the amount of drop) required can be determined by simply calculating how many feet on the Z axis the load must move. We will talk more about lift and drop later. Pros of hand manual chain hoists include portability, ease of use, and low purchase price. Cons are that these hoists are slow and require a lot of manual exertion to operate.
Electric Hoists – Probably the most popular type of powered hoists, electric chain hoists can be found in shops and factories worldwide. They are available in 1/8 ton all the way up to 100 ton capacities. Electric hoists utilize an electric motor to turn the hoists internal gearing which in turn raises or lowers the load connected to the load chain. The clockwise or counterclockwise rotation of the drum is controlled by the operator’s use of a pendant control featuring up and down buttons as well as an optional emergency safety stop. The Electric motors found in hoists more often than not utilize either 220v/ 440v or 230v / 460v voltage and typically require a hard wire type connection. However, some of the lighter duty shop hoists operate on 110v and can actually be plugged right into a household style electrical wall outlet. Electric hoists are fairly economical, but are limited in their use by what is known as its duty cycle. Every electric motor requires a certain amount of rest after a period of use. Disregarding the duty cycle ratings of an electric motor will result in premature motor failure and costly repairs. Electric hoists are not designed for 100% duty cycle operation and are not recommended for continuous production use. With that being said they can still provide a long service life when used in accordance with the manufacturers operating instructions.
Pneumatic (Air) Hoists – Pneumatic hoists are typically used in industrial production environments. These units feature either a rotary vane or piston driven air motor powered by compressed air. The greatest benefit of air hoists is that they have a 100% duty cycle rating, meaning unlike their electric counterparts, they never need to rest. Pneumatic hoists are however, only as good as the quality, pressure, and flow rate of the air that feeds them. One disadvantage of air hoists is that they consume a moderate to large amount of compressed air, which in turn calls for an air compressor capable of producing enough air flow to meet the cubic feet per minute (CFM) requirements of the hoist. Hoists operated below the rated CFM will not perform to their rated performance. Additionally, clean, dry, and lubricated air is critical to extending the operating life of an air hoist. The use of a filter, regulator lubricator (FRL) kit is highly recommended to optimize the service life between maintenance intervals.
Capacity – It should be fairly obvious that one of the first things to contemplate when selecting an air hoist is the amount of weight you will be lifting. Hoists range in capacity from 275 lbs. (1/8 ton) to 220,000 lbs. (100 tons). When choosing the right hoist for the job, always be sure to select a hoist that offers a little more capacity than that actually required by the job. When working with heavy objects you should always error on the side of safety. Also, you should ask yourself if the hoist might ever be used for another application other than the one currently in question. If this is the case, you might want to try and anticipate the weights of other objects to be lifted and plan accordingly.
Lift – The distance an object needs to be lifted vertically (on the Z axis) is the amount of lift required of the hoist. People sometimes refer to lift as the amount of “chain” required. The standard configuration for almost all hoists is 10 feet of lift. However, hoists are highly customizable and can be equipped with up to 99 feet of chain or more as required by the application. It is very standard for hoist manufacturers to modify the amount of lift of a hoist. Nevertheless, the greater the amount of chain requested the more expensive the hoist will be. Lift should be measured from the pick-up point of the object, to the bottom of the load hook when the hoist is in its fully retracted position. When calculating the amount of lift required, remember to take into consideration the actual height of the object being lifted. For example, if the distance from the lower hook of the hoist (in its retracted position) to the floor is ten feet, but the object and its pick up point sit two feet off the ground, only 8 feet of lift or “chain” is required. As with capacity, it is often better to have more lift than not enough. Again, try and anticipate whether someday this hoist could be used in an application requiring more lift and plan accordingly.
Drop – This simply refers to the amount of hand chain, electric cable, or air hose length offered as part of the control package. If for instance you are buying a hoist for a lowering application and plan on operating the hoist from a platform (think of unloading items off the deck of a ship unto a dock) adjacent to the hoist, you would most likely require a less than standard amount of drop. If however, you wanted to operate that same hoist from the area where the load pick up is to be made, you would need a considerably greater amount of drop.
Controls – Whether it’s a manual, pneumatic, or electric hoist; the length and type of controls must be carefully selected prior to ordering a hoist. As mentioned previously, a manual chain hoist (chain fall) is controlled by pull chain. Electric and pneumatic hoists feature pendant controls that dictate the lifting direction of the hoist. Electric models feature push button controls while pneumatic pendants utilize levers and valves to control the load. Older model and lower end pneumatic hoists sometimes feature two ropes connected to the ends of a small cylindrical stick which is tilted to the right or left to control the lowering or raising of a load.
Electric Hoist Pendant Control
Lifting Speeds – The lifting and lowering speeds at which a hoist operates are measured in feet per minute (FPM). Typically, there is an inverse relationship between the lifting speed and the capacity of the hoist. That is, higher capacity hoists operate at slower speeds and lower capacity hoists operate at higher speeds. Sometimes however, the same model hoist will be offered in the same capacity, but with several different options for the speed. Furthermore, some hoists are offered in dual speed models which provide greater flexibility in their use.
Hook, Lug, or Trolley Mounted – Hoists can be mounted in three basic fashions. Hook mounted hoists utilize a snap style upper hook to connect to a beam clamp, trolley, or pre-drilled hole in an I-beam. Hook mounting results in a less than rigid connection allowing the body of the hoist to sway with the load. In contrast, a lug mounted connection results in more rigidity because the upper suspension of the hoist is connected to a bracket or trolley using a solid metal rod known as a lug. This cylindrical rod, acts as a stabilizer bolt of sorts, preventing the hoist from swaying with the weight of the load. Lug mounted hoists can be stationary or mobile when mounted to a manual or motorized trolley. Trolleys allow the operator to roll the hoist laterally through the plant along the length of the I-beam.
Brands of Hoists – Ah yes, the old Ford vs. Chevy debate. The only plugs I’m giving here stem from my positive experiences with these products in the field. I’ve been involving customers with hoists for over six years and have placed 100+ units. Far and away the most reliable pneumatic hoists I have worked with are the Ingersoll Rand MLK series units. Ingersoll Rand has been building these workhorses the same way for over 25 years and with good reason, they’re ultra-tough, simple to operate, and they get the job done time and time again. Designed for 100% duty cycle operation in foundry, mining, and shipyard type environments, the MLK series hoists by Ingersoll Rand will hold up to a good amount of punishment and require little maintenance. Nonetheless, they should always be lubricated and will require the occasional tune up. On the other side of the equation, we have the electric models. I have had the best luck with the Coffing line of hoists which falls under the Columbus-McKinnon (CM) family of lifting products. With several different grades of quality that vary by application, Coffing offers a model to suit every buyer’s needs.
Conclusion – In review, throughout this article we have discussed the various components involved in proper hoist selection. Of all the factors, none is more important than selecting the right capacity hoist for the job and ensuring that you never exceed the manufacturers rated load specifications. Air hoists are the best choice for dirty production environments while electric hoists are well suited to maintenance and light industrial applications. Lifting speed and the amount of lift and drop also need to be carefully calculated prior to buying a hoist. Also, remember, to include a load trolley if your hoist will be traveling through the plant on an I-beam. Choose a hoist made by a reputable manufacturer such as Ingersoll Rand. Lastly, enlist the help of your local industrial distributor. Many of these outfits have undergone extensive manufacturer sponsored training and can prove to be an invaluable resource when it comes to properly qualifying a lifting application and making a sound recommendation.