Total Force Limit of a Simple Load Cell Configuration

[spggodd]

Hi,

I have a problem that I think had a fairly straight forward answer but I can't think of the correct forumla to calculate the value.

I have a two 10kN load cells in the configuration show below, the assembly is symetrical:

How do I calculate the total force that can be applied on the blue hub?

My guess was to just double it.. so 20kN but I'm not sure, can someone help?

Thanks
Steve

 

[spggodd]

Please check the attachement as the image fails to load.
Thanks
Steve

 

[rb1957]

the load cells are the brown things ?

your hunch seems reasonable to me ...

Quando Omni Flunkus Moritati

 

[MikeHalloran]

Yeah, the math seems correct, but you need another DOF (e.g. Hooke joints, not clevises) in the linkage to the jackscrews. Radial loads will surely screw up the load cell readings.



Mike Halloran
Pembroke Pines, FL, USA

 

[MikeHalloran]

You also need some kind of anti-rotation links on the thrust bearing assembly, so that bearing drag doesn't exert a radial force on the load cells.



Mike Halloran
Pembroke Pines, FL, USA

 

[BrianE22]

Is that a spline between the motor and center device? If so, the spline can produce an axial load and will rob (or add) to the load cell readings.

 

[MikeHalloran]

See, your first problem is that what you've drawn is NOT a 'simple' load cell configuration.


Mike Halloran
Pembroke Pines, FL, USA

 

[BrianE22]

Is that center object a thrust bearing? There then would be bearing friction and seal friction that will tend to rotate the support. I don't see anything to react that rotation.

Visually, it looks like a lot of mass connected to the two load cells. Have you looked at the natural frequencies?

 

[spggodd]

Very sorry about the lack of information, I thought It would have been a lot simpler.

The assembly is supported by two plumber bearings the location of which are shown as the shaded purple areas on the new attachment.
The central mass does include two thrust bearings. The assembly can twist but only very very slightly.

Yes the Load Cells are in brown.