Custom Made Lifting Device

[Danlemak]

Hi
I’m currently designing a custom made lifting device to provide better attachment during the lifting operation of a truck body. I picked up an ASTM A514 to be the best choice for the built up element (welded plates with a hook like shape). I selected that steel because of its high strength/weight ratio and relatively good toughness and weldability. However I’m not 100% sure if this is the best option or even if there are major drawbacks for using this material in this particular application. I really appreciate any comments regarding my choice. Thanks

 

[MiketheEngineer]

Just do a stress analysis - put about a 5:1 SF on it and you should be good to go.

OR buy one!!!

 

[MJCronin]

Dont forget to test the new weldment before use. Sign and retain test records. Keep a copy of a picture with the new weldment undergoing a test on file.

Test it at 125% of the max design load.

Then paint the max design load on the weldment......

 

[sixteenOfive]

I worked for a company that designed custom overhead lifting devices for all sorts of industries. We typically used heat treated 8620 and 4130/4140 (bar & plate, small devices). But depending on the size of your device, heat treatment might not be feasible. Design for 3:1 minimum and if your still unsure of your design & calculations you can always send it to a company like Ashley Sling, Mazzella, Letellier, or Alloy Sling Chain Industries to get it proof tested and certified.

 

[dhengr]

Danlemak:
You haven’t done a very good job of describing your lifting device or how it is going to be used. Remember that drawing something with a CAD program is a lot different than doing a good job of designing it and knowing how to build it, and is far short of doing a good stress analysis on it. Good clean details and welding, without stress raisers, etc., is all important. And, higher strength material will not overcome a poor design, which is difficult to build. Also, a few extra pounds of material on something like this is usually not the end of the world. And, you picked up “an ASTM A514,” but you don’t say if that is a quart or a pound or a plate or a shape, but in any case that material does require some special attention to welding. All-in-all it sounds like you should talk with one of your senior engineers about what you are trying to do. They can help you, and they should know what you know and what you don’t know about this kind of design, so as to help keep your company out of trouble.