HOW TO DETERMINE YOUR HOIST REQUIREMENTS
Hoist Capacity
Determine the maximum load to be lifted. If the load falls between standard rated capacities, always go to the higher capacity. (i.e., for 4,300 lb. maximum load, use 6,000 lb., 3 ton capacity hoists.)
Hoist Lift
To determine the total lift required, measure the distance from the bottom of the beam to the lowest point on the floor to be reached and subtract the hoist headroom dimension shown in the specifications. The remaining distance is the lift required on the hoist. Always select a standard lift equal to or greater than the distance required.
Hoist Suspension
Hook type suspension allows hoist to be hung almost anywhere and is used when hoist must be readily moved to other locations. Lug type saves headroom and is used with rigid mount trolleys or when hoist is permanently mounted in a fixed location.
Trolley Type
There are three standard trolley types that can be used to suspend Hoists.
Push Trolley – Recommended for light capacities and lifts below 20 feet. An economical method for moving loads.Hand-Geared Trolley – Offers most precise control for load spotting. Most favorable for higher capacities and short monorails where the control is desired. Also recommended where lifts are above 20 feet.Motor-Driven Trolley – Most widely used method of suspension, particularly 2 ton capacity and above. Virtually a necessity where long monorails are used.
HOW TO SELECT THE CORRECT ELECTRIC HOIST
First – Determine amount of travel /lift required per hour
This can easily be done by taking the distance a load must be lifted and lowered then multiplying by the number of times this must be done per hour to do the job required. Always use maximums that can be expected to occur. Example: Must lift pipe six feet to rack then lower hook for the next load 20 times per hour.
Second – Count the number of starts needed per hour
“Starts” are the actuations of the push-buttons. In our example, let’s assume, under a maximum condition, that in the raise cycle the hoist push-buttons are actuated six (6) times_in the lowering cycle, five (5) times. The number of starts per hour are calculated as follows.
Third – Calculate maximum load and average load
Maximum load is the highest load to be lifted and must not exceed the hoist rating. To arrive at an average load weight, take one up and down cycle (the heaviest anticipated), add the load on the hook in the up direction and the load on the hook in the down direction. Divide this sum by (2) and you will have the average load condition. Using 3,300 pounds and a below-the- hook weight of 300 pounds, average load is calculated as follows:
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Be sure to include weight of below-the-hook lifting devices. All Electric Hoists figures are based on the average load not exceeding 65% of the rated capacity of the hoist.
Fourth – Select the basic hoist
From our calculations, we know that we need a hoist that will lift a maximum load of 3,600 lbs., move the load 240’ per hour with 220 push-button starts, and whose average load is 1,800 lbs. From the following table you can select the proper hoist to do the job:
Note: Average load is used in lieu of the correct Mean EquivalentLoad for simplification: See ANSI/ASME HST-1M “Performance Standard for Electric Chain Hoists.?
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Note: The above chart is for single speed models only. On two speed hoists, the high speed winding is rated for HMI class H4 heavy duty, the low speed winding is rated for HMI class H3 standard duty (25% running time) service.
Continuing our example, we have selected a Catalog No. KELB2-10TH16S2 heavy duty hoist (2-ton capacity, 10-foot lift, 16 FPM lifting speed).
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65% at rated capacity of 4000 lbs.
As shown in the chart above, three phase hoists give superior performance and should be used whenever that power is available. Single phase, while universally available, should be limited to applications where infrequent lifting is the rule.
See ANSI/ASME HST-1M “Performance Standard for Electric Chain Hoists.?
If you follow this simple method of hoist application, you will never buy more hoist than you need, you can be sure the hoist will perform the required duty and you won’t find yourself on the short end of application versus hoist.
The duty rating as described will meet or exceed most industrial applications. Where the duty cycle is anticipated to exceed this duty rating, contact your representative or the factory to meet your need.