Bear in mind whether the load will have to be lifted over equipment on the shop floor or whether there are any overhead obstructions or ceiling restrictions as this will also reduce the amount of space you have available to lift a load. The crane itself has parts and pieces that will have to be factored into your calculations.
Stacking is an important consideration when deciding how high you have to lift the load. Stacking includes everything underneath the I-beam that effectively reduces its lifting height potential. Stacking includes the space needed for the trolley, sling usage, and hoist.
It is imperative to understand that a hoist must be suspended with a hoist/trolley combination or at least a beam clamp. You should never attach a hoist to the I-beam with a sling. Slings are frequently used to pick up both bulk materials and delicate or oddly shaped objects. While convenient, slings can add substantially to the “headroom” and thereby reduce the amount of space you have available to lift a load.
This image clearly shows that sling height is close to the headroom of most hoists, so make sure you are factoring that in when you are deciding on the height of your crane.
- Hoist Headroom – Hook to Hook Distances
- Hook Height – Distance from the top of the crane to the hook. Subtract this distance from the Overall Crane Height to see if a given crane will “fit.”
- I-Beam Depth – For a given capacity and span, this number cannot be changed.
- Trolley Headroom – Distance from the bottom of the I-beam to the top of the hook.
Example: 3-Ton Gantry Crane, Typical Sizes
The sketch above shows a “typical” trolley and hoist mounted on a 12” I-beam. As stated before, when you start to consider all the heights for the crane brackets, trolley hook height, I-beam depth, hoist “hook-to-hook,” the amount of available space “below” the hook decreases rapidly. Wallace sales staff are happy to help you choose the correct crane and hoist/trolley combination to meet your lifting requirements.