Building a Gantry Crane

Ken I was using the formulas on the link you posted for years, but now you have to pay a membership. Guess everyone has to make a living.
Glenn, for your trolley beam the design is usually based on deflection. If the beam bends too much you wouldn't be able to push the trolley up hill as you went to the side. Same as with a boring bar the strength of the material has no effect on that. Totally dependant on material (young modulus of elasticity) , cross section (specifically moment of inertia) and span.
Ran the numbers, for your 1800 pound load in the middle of an 8 foot beam you would get 0.011 inches deflection, not including the beam weight. Might get that much more from the weight of the beam. The calculations were from a new sight I found, was too lazy and its too early to check the numbers by had but that sounds about right for that size beam.

Greg
 
Greg,

On deflection, that's about right. And yes, you can't get around it, any material will deflect a certain amount based on Young's modulus. My question to you is, what was the stress level at this level of deflection?
 
You have to pay to get the calculator I found to give stress Ken. Wish the one you linked to was still free. With that deflection on an 8 inch beam you'd be no where close to the elastic limit.

Greg
 
Greg, Thanks much for doing that. Very good to know. Sounds like reasonable deflection for what I will be doing.

Bear, nice looking design. Can you advise the width between centers of your casters? This is the one dimension that seems the most variable with people I have talked to.

Glenn
 
No problem Glen, That deflection over 4 feet from centre would be unnoticeable when you tried to move the trolley.

Greg
 
The gantry crane dad had, legs were 4 foot apart, up rights about 8 foot, or put this way, the overall height was right at 10 foot.
 
My casters are 5 feet 9 inches apart... it is very stable at this width. I would think you could make it a good bit narrower and not have to worry about it being tippy.
 
Back
Top