When is 1 Ton Greater than 1 Ton?

We’ve all used chain motors and we’ve all suspended the maximum 1 ton rated loads. But do we ever really think about what happens between the 2 hooks?

If you are an operator, you have probably been trained to understand forces. A load in motion exerts greater forces than a static or non-moving load. Load position and hoisting speed affect the magnitude of these forces, which can be measured in excess of 200%. This alone should be sufficient to make us more cautious when using overhead lifting equipment.

But what if I told you the forces mentioned above are overshadowed by the force we see in the inter-link of our load chain?  The contact area where 2 links touch is only .006 inch. With a one ton static load on the hoist, pressure between links can be as high as 500,000 pounds per square inch. If this is not enough to open your eyes, think of a stage using (12) 1 ton hoists each performing a 40 foot lift. We have 6500 working links, each one subjected to 1/2 million PSI. Moving the load increases this pressure. Imagine the amount of friction and resulting heat.

Is lubrication on the load chain really necessary? Tell us what you think.