Steel Plain Bearing 1

[lever57]

I have an application in which a .5 dia steel shaft carrying an 1800 pound radial load is supported by two steel bushings. Each bushing is .5 inch long. This bearing/shaft combination must operate at about 1 rev/sec with little or no lubrication. What should the shaft and bushing hardnesses be in order to have max bearing life? Will zinc plating on the shaft accelerate the wearing that takes place? Can any type of case hardening be used?

Tom P.

 

[Barry1961]

Sounds like a tough application. I would ask some plating people about teflon impregnated chrome or nickel. The stuff is really hard, slick and very corosion resistant. I used to have a place down near Orlando, Fla do parts for me but I can't recall the name. I was very cheap to get done and most of the time out qty of parts would not meet the min so we would make the volume up with "goverment" parts.

I want to say that a it was around $200 for a small basket of parts.

There are some very tough and thin plane bearing out there, Garlock makes some that may work for you. The DU series are self lube and good for around 50,000 psi-fpm. With you speed being so slow it might work.

Barry1961

 

[ccw]

Hi lever57,
The railroads used to call these type of bearings of (journals running with no lubrication) "hot boxes". The firemen would walk the length of the train when it was temporarily on a siding and pull the burning, smoking, packing out of the boxes, replace the packing and replinish the oil. Later the railroads replaced the journal bearings with anti-friction roller element bearings on all their rolling stock. Timken made a fortune and no more hot boxes. Practically any kind of roller element bearing would be better than a steel-on-steel journal running with "..no lubrication.." as you describe.

 

[sreid]

I agree with CC. Shell type needle roller bearings might be the solution.

 

[unclesyd]

If you have to use a steel bushing here is the type of bushing you need. These are the readily replaceable type

http://www.connexusa.com/HTML/principle.html

 

[lever57]

Thanks for all these helpful replies!
Tom P.

 

[Carburize]

Does it really have to be a steel bushing?
Could a high lead bronze be used?

 

[unclesyd]

ccw,
I maybe wrong but I don't think railroads ever used plain steel bearings unless it was very early on. I seen pictures of my grandfather taken in the early 1880's standing beside a railcar with brass or babbitt bearings. The bearings were essentiall a half bearing supported in the trucks and setting on top of the axle. The bearings had an arrangement where there was a reservoir on the outside that contained a wicking material Oakum that helped keep the bearing lubricated. I still have one of the very long neck oil cans that allowed the trainman to oil the bearing while he remained standing.
One of the oils they used in the 30's until the end of the bearing, was an oil made by Sharvannia. This was highly sulfurized, high temperature oil, that I ran into again in the late 50's as we used a Sharvania steam cylinder oil.

 

[ccw]

Hi unclesyd,
You are correct as far as I remember. I told the story to emphasize the result of metal on metal journal with "no lubrication" as was stated in lever57's original post and to recall the advantage of rolling element antifriction bearings which can continue to function with no lubrication. Most heavy loaded journals I have experience with do not work well without the lubrication film with some exceptions like graphite.

What was the purpose of the soft babbit or brass inserts vs. some other material?

 

[unclesyd]

The reason for the brass bearing it was an easily cast component that was easily machined to a correct diameter, for turned journals. There weren't too many other materials available during the early days of the RR. Bearing on wagons and coaches were still Oak. Brass had been around for awhile and babbitt came in around 1840 but at the time wasn't hard enough for use in RR bearings until the late 1890's. They were efforts to use roller bearings in the early 40's but testing was interrupted by the war and it wasn’t until Torrington improved the metallurgy and adapted the Tapered Roller Bearing around 1960 that they could get a successful test run out of train car.
The bearing essentially actually sat on top the axle journal restrained in a housing so that with a railroad jack two men could change the bearing in about 2 hrs by simply jacking up the trucks. In a shop you could pick up the car and put new set of wheels in few minutes.

An interesting note about the RR tapered roller bearing is in the early 80's NASA was able to get over 1,000,000 dN out of a heavily loaded standard RR bearing simply by drilling small radial holes in the outer race.

 

[aamoroso]

Look into an Oil Impregnated Bronze,I don't know if it will suit your situation but worth looking into.

If you are looking for plain bearings or teflon coated check out INAs permaglides, I have used them in the past under extreme loads and low RPM.

Fill what's empty. Empty what's full. And scratch where it itches.