I am looking to use a needle bearing and a needle thrust bearing together.  The needle thrust bearing will use a .032" washer on both sides.  The shaft diameter is .75", the OD of the needle bearing is 1", the OD of the thrust bearing is 1.25".  So good portion of the washer will go unsupported due to the bore of the needle bearing.  My question is, how much of that washer can go unsupported?  This has to be a common setup how do people get around it?




 

The washer is too thin to go partially supported.
You could:
- Put a bulkhead or a heavy backup washer behind it... and move the radial bearing farther out.. maybe not so good.
- Use a thrust bearing that's a size or two larger, and put a step in the shaft to pilot its i.d... and make the shaft stronger and stiffer between the rotating mass and the radial bearing.
- Put the thrust bearing on the very end of the shaft, bearing on a plate bolted to the end of the shaft, allowing you to put the radial bearing closer to the radial load.
- Use a tapered roller bearing to replace both bearings.


 

Mike Halloran
Pembroke Pines, FL, USA

Use a combination bearing?

http://www.ikont.co.jp/eg/download/pdf_eg_catalog/cat5502dNAX.pdf

Russell Giuliano
 

I was looking at a thicker washer... they come .030, .060, .092, .123, and .154.  To put anything thicker than the .030 will require additional machining, that is the reason I started with .030.

All the other ideas are great if this was a clean sheet design, unfortunately I am stuck with the shaft, housing and radial bearing...just need a method to control the thrust.

I actually like the combination bearings a lot, I was looking at the Timken ones.  But for some reason they only come in metric.  

Thanks for the ideas!

What's your thrust loading estimate?

Pretty light, it is an idler gear, so there is no real thrust just a moment of ~133 ft lbs...I am thinking most of that will go into the radial needle bearings and very little will actually go into the thrust bearings depending on the clearances...  I have attached my chicken scratch if you can following it....

 

• http://lh4.ggpht.com/_RzOtO1BNhKo/SQ_UelxWjEI/AAAAAAAABy4/5DXg0Poo8MA/s800/