Large Bushing 1

[22west]

I am looking for some info on the design of large greased bushings. I have a 10 foot diameter, very low RPM shaft subject to a large bending moment.

Any reference design books or even a potential supplier would be a great help.

Thanks.

 

[MikeHalloran]

It's certainly possible to make a plain bearing that big, but Small Parts doesn't stock 'em.

One traditional solution is a piece of railroad rail, bent into a circle the hard way, and supported by a pair of double- flanged crane wheels, or for really heavy loads, several bogies equipped with crane wheels.

Another traditional solution is a circular band of thick steel, supported by bogies having slightly crowned but otherwise plain roller wheels.

Look for pictures of ready-mix trucks and cement kilns.



Mike Halloran
Pembroke Pines, FL, USA

 

[ornerynorsk]

Just what is meant by a large bending moment??? You must be talking 1000's of tons for a shaft that size. Can you live with a segmented plain bearing with pressurized lube? Of course, the housing or support structure for those bearing pads will be monstrous in size and weight.

 

[DesignerMike]

I have often seen (and used) the wheel and caster design that Mike refers to. Machining (or bending) the rail is the tricky part, and getting everything running straight is another challenge. Usually not designed to handle any moment load on the bearings without some additional carriers.

I have also had some good luck using a turntable bearing in an application similar to this (just not nearly this big). Kaydon has a 96" on their "standard" offering brochure which can handle 4,975,000 ft-lbs of moment load.

I'm sure they are pretty much made to order, and would be able to build any size you want. The bearing may cost a little more, but the machining costs are so much less.

 

[diamondjim]

Try Rotek, PSL, Kaydon, SKF, Timken

 

[minerk]

Try Excel Foundry or Pyramid parts, both supply huge bronze bushings for mining equipment. Not sure if Pyramid will do a custom bushing, but I'm pretty sure that Excel will.