Non-lubricated Large Bushing in Mining - Material and Design 4

[kkubo]

I am looking for a way to improve our pin connections used in large mining equipment. The pins diameters range from 3-10" with bearing pressure reaching 7500 psi. The velocities are very low with small osciallation. And of course the bushing/pin will see dirt and impact loads, and no p/m will ever be done (hence non-lubricated). Traditionally, manganese steel bushing with 4340 pins have been used with poor results. Is there better choice of materials? I also could use a good sources of design information (rule of thumb for hardness difference, design methodology, ect).

Thanks,

Ken

 

[unclesyd]

Same approcah but a different material.
Here is the one that I've always used. I don't know about the available diameters. They do go to 3". I would give them a call to see what is available.

http://www.rollpin.com/ProductInformation/TensionBushings/index.html

 

[Tmoose]

Thru what arc do the joints move?

What do Caterpillar and Komatsu do?

Boosting hardness can help some with pure abrasion, but running similar metals unlubricated can bring on BIG galling problems.

I have to think incorporating less-similar materials, , with highly finished round holes and shafts, EP dry lube at assembly, and rudimentary sealing (even at the expense of projected bearing area) would reap huge benefits.

 

[EdDanzer]

There have been several threads about plain bearing you should read. Most lubricants have a film strength below 7500 psi., so you will have dry metal running against dry metal. If the pin bends much you will see galling at the ends of the bushings, and this will destroy the bushing bore.

 

[dimjim]

I wonder if a higher nickel steel would
help like the aisi 8660 for the pins
would be a better choice. They are coating
a lot of shaper cutting tools to make them last
longer. I wonder if that would help in
this case.