Talk:Plain bearing/Archives/2014

Failing sleeve bearings - dry concentric walking?

I don't know if there's an existing engineering term for this, but it would seem useful in the article. This occasionally happens with consumer devices like vacuum cleaners, which may contain maintenance-free motor sleeve bearings. This seems to be different from "oil whip" as mentioned in the article.

This happens after several years when the shorter-chain thin volatile chemicals in lubricants evaporate away, leaving behind the thicker waxy lubricant components. It can also happen if the lubricant is contaminated with dust. In either case the lubricant becomes high viscosity (slimy/sticky).

Bearing surface friction increases until rather than the two surfaces sliding across each other, they actively stick together and the inner shaft starts to concentrically "walk" around the inner face of the fixed bearing surface. When this happens the inner shaft starts to emit a shrieking noise due to oscillating at great speed, as it very rapidly circularly walks the inner wall of the sleeve as it rotates.

Usually when this shrieking starts to occur, the bearing seems to rapidly be damaged beyond the point of relubrication, as the rapid oscillation generates heat and also etches the sliding surfaces with any fine dust debris trapped between the shaft and outer bearing.

The heat and friction of concentric walking can also cause bearing sleeve inserts around the shaft to become seized onto the shaft, and the sleeve insert itself begins to rotate within its mount in the device, destroying the fine tolerances of its mounting pocket, requiring full replacement of the shaft, sleeve, and mounting frame.

-- DMahalko (talk) 06:39, 10 October 2014 (UTC)

... And then they get to sell you another one. :-) Ha, ha, but in all seriousness, thanks for contributing this analysis. It is interesting. — ¾-10 23:54, 10 October 2014 (UTC)

Axleboxes, whoa

According to the reference, axleboxes contain a type of rolling-element bearing, see "The evolution of railway axlebox technology". Evolution online. Retrieved 18 September 2014.!. Not a plain bearing at all! Peter Horn User talk 21:24, 18 November 2014 (UTC)

That is re Plain bearing#Design Peter Horn User talk 21:41, 18 November 2014 (UTC)

This was implied by the past-tense wording "referred to the plain bearing once used at the ends of the axles" (emphasis mine). I added a sentence expressing that RR bogies today use rolling-element bearings. BTW, I vaguely remember reading an article or advertisement in a publication from circa 1900 to 1930 that bragged about the first locomotive built in America with Timken tapered roller bearings on all the wheels. It was clear from the tone that it was really a gee-whiz moment for railroad mechanics, like "can you believe we've arrived in an era when such things are the new normal? Amazing!" Same kind of tone used by people in the 1960s to write about IBM mainframes and rockets to the moon. — ¾-10 22:47, 18 November 2014 (UTC)

When I look at the first illustration (image) in the reference, I see an axlebox minus its cover and thus exposing cylindrical, longish, rollers on the circumference of the axle. I suppose that was the original arrangement within the axlebox and that things evolved from there, as the additional illustrations show. I guess that with adequate lubrication the original arrangement was as effective as any more modern arrangement. Peter Horn User talk 15:41, 19 November 2014 (UTC)

As discussed at Talk:List of railroad truck parts, the term "axle box" is not idiomatically restricted to only those boxes that contain roller bearings. More info there. — ¾-10 02:35, 20 November 2014 (UTC)