While reviewing some old photos in a book of SP steam in the 50’s, they talked about Friction bearings and Roller bearings on their rolling stock. Which of the two are better? The captions under some of the photos stated that Roller bearings were better but Friction bearings were cheaper. If you keep keep them greased, shouldn’t either one do the job? Could someone also explain what “wool waste” on Friction bearings is? Thanks
Larry
Friction bearings are like plain bearings. Think crankshaft bearings in your car’s engine.
Roller bearings are like the bearings in your car’s wheel hubs.
Roller bearings are far superior because they are smaller, lighter and can be lubricated with grease. plain bearings require oil lubrication. The wool waste works like a wick to bring lubricating oil from a small reservoir beneath the bearing up to the bearing surface. Plain bearings require more frequent inspection, mostly to ensure that the lubricating oil has not leaked out.
In its waning years, the Chicago, North Shore & Milwaukee was plagued by “hot boxes”, which result from friction bearing failure. An employee suggested to management that they replace the friction bearings on the cars with roller bearings, a couple of units at a time, to solve the problem. However, the CNS&M’s management was not interested in improving the line, so the plague continued.
Roller bearings also offered at least a partial solution to the problem of dynamic augment on steam locomotives.
IIRC, roller bearings are now required by Federal law on all rolling stock in interchange service.
Thanks fellas!
Larry
Thank you Mark, you beat me to the chase.
my buddys got friction bearings on his caboose he restored. I give him my waste oil from all my mowers (thats a lot, trust me). Without him, i would pay a million to “dispose” it.
Adrianspeeder
One of the problems with roller bearings and steam locomotives is that, as Mark said, there was a metalurgy problem. The thrust of the piston would create such dynamic forces that would change quickly that the bearings would fail rather quickly when used in the side rods. So, most of their use in steam was on axel bearings, but even there, steamers had dynamic force problems.
In later years, since wool waste was a bit flamable, an improvement was made called a lubricator pad that would lay in the bottom of the bearing box and act like wool waste. Much improved over waste.
As to how effecient rollers are, we had a rule of thumb on the SP for several years while the conversion was taking place to rollers, that - on a car equivelent basis, two roller equipped cars equaled one friction bearing car.
If I remember correctly one of the Northern Pacific’s Northerns was equipped with Timken roller bearings.
From an engineering standpoint roller element bearings are superior to friction bearings in that they don’t have to be inspected as frequently to ensure an adequate supply of lubricant. Add to that hot boxes rarely occur with rolling element bearings. Rolling element bearings’ signatures can be monitored to determine their condition so advance warning of failure is possible.
The ICC has required rolling element bearings on all interchange rolling stock since the mid 1960’s.
Used motor oil has corrosive combustion byproducts, it my not be a good idea to use that for a bearing.
I could be wrong, but steam locomotives have a lot of lateral play and loading in their driven axels, which could be less than ideal for roller type bearings, unless somehow tapered bearings were used to handle axial loads.
I had a thought since this last post. If a steam engine’s driven axels were allowed to move freely lateraly through the the bearing’s center, a roller type bearing would only be loaded in the vertical plane. Limiting the axels’ lateral motion would still be a problem though.
I read somewhere that it was attempted in recent times to convert an older steam loco to roller bearings unsuccesfully.
I could be wrong, but car trucks actually use tapered roller bearings? The axels are fixed lateraly in relation to the truck frame, or is it necessary to have end play in car truck axels?
I have read that steam locos have tapered blocks to locate the bearing journal blocks, the tapered blocks adjusting for wear. Are the blocks at either end of an axel used in conjunction to keep an axel square to the frame? How does this affect center to center distance between two driven axels? In a 4-8-4 for example, which axel is the “reference” for the other axels’ center to center distance?
Maybe these are obscure questions, If nobody knows, maybe point me in a direction, I have a genuine interest in this question.
Interesting that in the late '20s it was recognized that running resistance of roller vs. plain bearings was not that different. The reliability and ‘sealed maintenance’ characteristics of roller bearings imho are more significant than starting antifriction in many cases. I remember (I think) that the limiting lifetime of Timken freight-car bearings was limited by wheel wear, rather than anything about bearing metallurgy or tribology, as early as the 1970s.
With respect to steam roller bearings, the situation is a bit complex. The NP engine is, of course, the famous “Four Aces”, built for Timken as a demonstrator; a successful as well as good-looking locomotive. Many roads did not use roller bearings in the trailing truck, due to firebox heat and ash problems, if I remember rightly.
Rollers on the driving axles could get interesting. N&W, and perhaps other roads, had early versions that were incorporated in the hubs (Louis Newton has a rather good picture of one in his Rails Remembered volume 3). Something like this was my solution to the inside cranks on a Withuhn conjugated duplex locomotive, where the inner race diameter of the ‘main’ drivers is very large, greater than the crank circle; the hollow axles are of very great diameter, and external bridges between the bearings, outside the throw of the conjugating inside rods, provide the necessary lateral stiffness. Main drivers are not ideally provided with lateral motion, so there is less problem with designing suspension, frame, etc.
Later modern steam power used very substantial axlebox structure (IIRC called a ‘cannon box’ or something similar; I don’t have references nearby) to keep the bearings “perfectly” aligned; this lessened the requirement for tight and near-perfect adjustment of axle alignment in the frame (e.g. via Franklin self-adjusting wedges). Timken used tapered rollers, while SKF used a barrel-shaped roller (which had some of the lateral self-aligning and thrust geometry of a ball bearing wh
The oil isnt in there very long, and is diluted with other oil. By the way i am also runnin full synthetic for max cooling for the time i run these little air cooled motors.
Adrianspeeder
Adrian, you mention “the oil isn’t in there very long”…, isn’t this caboose static in location…What happens to the oil…? And another question…I’ve thought of using synthetic oil in my John Deere lawn tractor, have you had good luck using it in your mowing equipment…?
[quote]
QUOTE: Originally posted by Overmod
Interesting that in the late '20s it was recognized that running resistance of roller vs. plain bearings was not that different. The reliability and ‘sealed maintenance’ characteristics of roller bearings imho are more significant than starting antifriction in many cases. I remember (I think) that the limiting lifetime of Timken freight-car bearings was limited by wheel wear, rather than anything about bearing metallurgy or tribology, as early as the 1970s.
With respect to steam roller bearings, the situation is a bit complex. The NP engine is, of course, the famous “Four Aces”, built for Timken as a demonstrator; a successful as well as good-looking locomotive. Many roads did not use roller bearings in the trailing truck, due to firebox heat and ash problems, if I remember rightly.
Rollers on the driving axles could get interesting. N&W, and perhaps other roads, had early versions that were incorporated in the hubs (Louis Newton has a rather good picture of one in his Rails Remembered volume 3). Something like this was my solution to the inside cranks on a Withuhn conjugated duplex locomotive, where the inner race diameter of the ‘main’ drivers is very large, greater than the crank circle; the hollow axles are of very great diameter, and external bridges between the bearings, outside the throw of the conjugating inside rods, provide the necessary lateral stiffness. Main drivers are not ideally provided with lateral motion, so there is less problem with designing suspension, frame, etc.
Later modern steam power used very substantial axlebox structure (IIRC called a ‘cannon box’ or something similar; I don’t have references nearby) to keep the bearings “perfectly” aligned; this lessened the requirement for tight and near-perfect adjustment of axle alignment in the frame (e.g. via Franklin self-adjusting wedges). Timken used tapered rollers, while SKF used a barrel-shaped roller (which had some of the
I submitted a similar question here on roller bearings, see “Roller Bearings” 6 Apr 2004, but didn’t get an exact answer. There’s a magazine citation there also. It was different in that I wondered how much more efficient the locomotives became once they were pulling roller bearing freight and passenger cars. I guess it took something like the government to mandate roller bearing for rolling stock, much like air brakes were, because ownership was diffuse.
I do believe that friction bearings can also no longer go through interchange with other railroads.
I believe the famous photograph of Charles Atlas pulling the Broadway Limited train using a rope over his shoulder was meant to advertise the roller bearings on the trucks.
I have seen advertisements in 1960s era issues of Railway Age magazine for an oiled waste substitute for friction bearing trucks that looked like a chunk of shag carpeting.
Dave Nelson
Chet Huntley wrote a book eons ago where he described a locomotive in Montana that was used to demonstrate how well roller bearings worked. As I recall, the ladies of his hometown were all invited down to the station, issued gloves, and asked to pu***he locomotive. It moved… I kinda doubt we would be able to do the same with locomotives today, gloves or not…
Erik
The Four Aces (road number 1111) as I recall – she was a standard Northern with Timken supplied roller bearings everywhere, for testing.
The only down side to modern roller bearings that I know of is that when they fail (and they do – everything does, now and then) they give you less warning and a lot less time than friction bearings. The chaps watching and listening to the ‘hot box’ detectors have to be a lot more vigilant, as a bearing can go from no problem to ‘oops, d__n’ in a remarkably short time[xx(].