off set bearing loads

[swcaddesigner]

Hello, Trying to size a bearing/s that can take an offset loads. Approximately 5000 lbs @ 131 inchs & 2500 lbs @ 9 in away from first bearing or pair. Bearings are mounted vertically.
I am allowed 1mm deflection and speed is very slow 5 rmp. Smallest bore the better.
We also might add counter weight on opp. side(lower) for safety,
I think this is a simple calc but would love assistance.

 

[Tmoose]

what is the spacing between the bearings?

 

[swcaddesigner]

Thanks for asking.

Spacing between the bearing is 80 in but can increase some if needed.

 

[dvd]

I would consider a slewing ring bearing, like Rotek, as an alternative to shaft and bearings.

http://www.rotek-inc.com/files/Rotek_84pgCat_FINAL_ViewOnly.pdf

Yours is a fairly serious application that really should have a responsible party in charge.

Caution about counterweight increasing the mass moment of inertia to the point where starting and stopping the load becomes an issue.

 

[tbuelna]

swcaddesigner,

If the direction your loads are applied is fixed with respect to rotation, then your bearing system must be able handle radial forces and moments. With your offset loading condition the bearings will be different sizes if you want to optimize the system.

As for maximizing mounting stiffness with minimum bearing diameters, your best bet is probably a pair of tapered roller bearings with preload.

Good luck.
Terry

 

[swcaddesigner]

Thanks. I have been checking out the Rotek Slewing Bearing and thier engineering assistance. I am doing a first rough pass but will employ a PE with Cosomos experience soon.
Thanks for the advise on counter weighting.