Rack toppling

[moon161]

I'm designing a rack for material handling, 5' high, casters, 3lb of parts hang from the top + self weight.

Is there a good reference for minimum moment/angle/displacement to topple it? I was thinking about 2' wide at base, like a hat rack or IV stand.

 

[flash3780]

My old engineering mechanics book (R.C. Hibbeler) discusses tipping in the chapter about friction. Start by drawing a free body diagram to determine what force will cause a moment large enough to exceed equilibrium.

 

[MiketheEngineer]

What always worries me about these types of things is "sudden stopping".

Say you were pushing it along and it hits a bump in the floor or better yet a 2x4. Then not only does the weight of the rack and material come into play - but you trying to stop yourself by psuing even more on the cart.

Just a thought

 

[flash3780]

Draw a free-body diagram something like the one I've attached and sum the forces and moments. You should be able to determine the maximum amount of weight that the rack can support without toppling by solving for it. Of course, you'll want to have a safety factor.

 

[drawoh]

moon161,

I asked this question in the structural engineering forum.

thread507-255357

JHG

 

[gruntguru]

Don't forget the casters will always work against you, ie design for worst case - wheels aligned toward the CG

Engineering is the art of creating things you need, from things you can get.

 

[TED7]

Also dont forget that it will be loaded at maximum unbalance fairly often - despite how you tell people to load it.

Will Walters
Sheffield UK
Designer of machine tools - user of modified screws