Plain or sleeve bearings are replacing rolling-element bearings in a wide range of products including pumps, wind turbines, and equipment for agriculture and construction. Once it was thought that complex parts required complex rolling-element bearings, but designers are learning that plain bearings’ design simplicity has its advantages.
http://machinedesign.com/article/plain-bearings-outperform-rolling-element-bearings-0407
No mention is made of rail car, nor locomotive axles. Could advances in material technology take us back to the future?
That would be amazing if the sometimes called "friction" (plain or sleeve) bearings made a comback. Back to the future indeed.
I would not conclude that this would amount to the return of the railroad axle journal box, however.
I read the report. It is really interesting but did you notice the applications mentioned? Other than "tractors" nothing was mentioned about HEAVY transport applications. When it comes to rail cars, we're talking solid tonnage that's subject to frequent pounding/jolting and lateral stresses. But if this new generation of friction bearings has been or will be engineered to withstand that type of punishment and have a service life that's comparable to or better than the typical Timken rollerbearing, then it's a safe thought that the Class 1s will take interest.
"I like my Pullman Standards & Budds in Stainless Steel flavors, thank you!"
plain bearings are used in high shock applications. For instance the EMD high emergency diesel generators on aircraft carriers use a ATI generator on both ends but they are provided by high pressure lube oil from the engine oil pump. EMD as sold some switchers with plain bearings for use on extremely rough track ( read high shock ) but they never went very far from the shop so the oil reservoir could be checked frequently. The point is that unless you can provide an oil circulating pump on each axle of every freight car you are stuck with the oil system and its "hot box" problem.
While there's maintenance with any mechanical device, there's a whole lot more maintenance on "friction bearings" than with the roller bearings in use today.
Gotta remember to fill up my can of journal oil...
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
creepycrank "...plain bearings are used in high shock applications. For instance the EMD high emergency diesel generators on aircraft carriers use a ATI generator on both ends but they are provided by high pressure lube oil from the engine oil pump. EMD as sold some switchers with plain bearings for use on extremely rough track ( read high shock ) but they never went very far from the shop so the oil reservoir could be checked frequently. The point is that unless you can provide an oil circulating pump on each axle of every freight car you are stuck with the oil system and its "hot box" problem..."
"...plain bearings are used in high shock applications. For instance the EMD high emergency diesel generators on aircraft carriers use a ATI generator on both ends but they are provided by high pressure lube oil from the engine oil pump. EMD as sold some switchers with plain bearings for use on extremely rough track ( read high shock ) but they never went very far from the shop so the oil reservoir could be checked frequently. The point is that unless you can provide an oil circulating pump on each axle of every freight car you are stuck with the oil system and its "hot box" problem..."
[quote user= "Antonio FP45"] "...by AntonioFP45 on Fri, Jan 4 2013 4:48 PM
"...Plain (friction) bearings were prohibited from cars in interchange effective January 1, 1994.
Converted side frames (plain to roller bearing) prohibited for tankcars carrying hazardous commodities effective January 1, 1992; all cars effective January 1, 1995.
Generally railroads adopt the interchange rule when accepting cars on intraline service.
There is nothing I know of in 49 CFR or AAR rules prohibiting the use of friction or plain bearings. However, there's no rule that MAKES the railroad have to accept equipment with plain bearings, either..."
RWM
and this post wold seem to make the subject of returning to a National Railcar interchane fleet equipped withfriction bearings, pretty much a moot point as, I suspect the shear costs of replacement and the maintainance/upkeep of such friction bearings would be a financial hemorage for the Industry:
dredmann said on Mon, Dec 31 2007 1:47 PM
(1) replace the trucks with trucks containing roller-bearing axles;(2) replace the axles with roller-bearing axles (if possible, which sometimes it is, IIRC typically at a cost of about $2000 each for used roller-bearing axles, plus labor);(3) put the whole thing on a flat car or (highway) truck to transport it;(4) ship it only to another point on the short-line railroad where it may have been operating; or(5) get a special waiver from the railroad(s).An organization with which I'm involved regularly runs into this issue. We have been scrounging roller-bearing axles that we can swap for friction-bearing axles on old passenger cars. The friction-bearing cars aren't allowed to move outside the yard. The roller-bearing cars have been taken a thousand miles from home, and have rolled on multiple Class I's. Work is ongoing to do this swap on two or three old passenger cars..."
The linked article is NOT about the friction bearings, hand oiled journal boxes, waste pads, and hotboxes of yesteryear. It is about replacing high cost roller bearings with sleeve bearings that can deliver the same performance at less cost.
I'd personally like to see plain brass bearings in GE traction motor armature supports....
Plain bearings on railroad freight car axles will NEVER happen. Too many of us old guys remember them well enough to know better. I have seen roller bearings fail but not as frequently as plain bearings.
Randy
Advances in solid lubricant technology may make plain bearings practical, though the increase in rolling resistance could outweigh the lower initial cost. I would suspect the solid lubricants would have a shorter life than the grease used on roller bearings, so maintenance costs could be higher even if they have as low a failure rate as roller bearings.
Note that roller bearings are very rare on the crankshafts of internal combustion engines.
- Erik
Anything that increases maintenance requirements for successful operation is a non-starter with today's railroads.
Never too old to have a happy childhood!
BaltACD Anything that increases maintenance requirements for successful operation is a non-starter with today's railroads.
Your basic premise makes complete sense to me, but I do have a couple of very general questions.
First question is if the railroads would be willing to use a shorter schedule for replacing bearings if the replacement bearings are substantially cheaper? (Note that "shorter" maybe be a period of several years for the new friction bearings.)
Second question is whether the railroads avoidance of "increased maintenance requirements" is more towards avoiding scheduled maintenance or unscheduled maintenance?
I'm far from convinced that the new friction bearings are ready to replace roller bearings on RR cars, but the advances in bearing technology are intriguing. First thing is to see a lot more data on longevity with the new bearings.
Proper maintenance and the way its treated and designed is the key for longevity. Our company (Sand and Gravel) tried the extended oil drains recommended by Caterpillar and Shell. We had gone from a 12,500 mile service interval to a 15, 000 mile interval on 10 out of 35 tractors. Bearing wear and isolated bearing failures was the result. Out of 25 heavy haul tractors going the 12,500 mile interval not one has needed a bearing roll in in 3/4 of a million miles plus. The 10 tractors we tried the extended drain interval saw 3 bearing and crankshaft failures, 3 bearing roll ins at less than 500,000 miles, broken rocker arms and a camshaft failure. Like the old Fram filter commercial said "Pay me now or pay me later"
Now when it comes to the tapered roller bearings in our trailer axles. We had started going from the oil bath hubs and covers to a new Synthetic grease. We have trailers that have well over a million miles without a bearing or seal failure. The oil bath hubs had failures with seals and bearing wear sometimes monthly. We have yet to have a failure of the greased bearings. They have shown to be maintenance free.
Transmission failures continue to happen. These failures are more to do with the driver then either the parts or lubricant.
Impact failures in our differentials is almost non existent since going to a Synthetic gear oil. Running mineral oil based lubricants saw sporadic failures usually when the truck was stuck and the driver bounced it out. Since going all synthetic there has been no failures even though they still get stuck.
Pete
I pray every day I break even, Cause I can really use the money!
I started with nothing and still have most of it left!
erikem First question is if the railroads would be willing to use a shorter schedule for replacing bearings if the replacement bearings are substantially cheaper? (Note that "shorter" maybe be a period of several years for the new friction bearings.)
Too many factors to give a definitive answer. If the cost of replacing the bearings on a regular basis in terms of labor and facilities, plus the cost of the bearings, is less than the cost of the status quo, then they might look at it favorably. MTBF (mean time between failures) will also be a factor. I don't have the numbers to make a call.
Both, actually.
I'm far from convinced that the new friction bearings are ready to replace roller bearings on RR cars, but the advances in bearing technology are intriguing. First thing is to see a lot more data on longevity with the new bearings. - Erik
Agreed. While there currently appears to be no reason to change from the status quo, technology has a way of progressing anyhow...
tree68 erikem First question is if the railroads would be willing to use a shorter schedule for replacing bearings if the replacement bearings are substantially cheaper? (Note that "shorter" maybe be a period of several years for the new friction bearings.) Too many factors to give a definitive answer. If the cost of replacing the bearings on a regular basis in terms of labor and facilities, plus the cost of the bearings, is less than the cost of the status quo, then they might look at it favorably. MTBF (mean time between failures) will also be a factor. I don't have the numbers to make a call.
By no means do I have the necessary information either, and I suspect relative costs can vary over time as well.
erikem tree68 erikem First question is if the railroads would be willing to use a shorter schedule for replacing bearings if the replacement bearings are substantially cheaper? (Note that "shorter" maybe be a period of several years for the new friction bearings.) Too many factors to give a definitive answer. If the cost of replacing the bearings on a regular basis in terms of labor and facilities, plus the cost of the bearings, is less than the cost of the status quo, then they might look at it favorably. MTBF (mean time between failures) will also be a factor. I don't have the numbers to make a call. By no means do I have the necessary information either, and I suspect relative costs can vary over time as well. - Erik
The expected bearing life on freight cars is until the wheel set needs changing because of wheel defects, high wear rate creating 'condemable' thin flange, severe flat spot (now-a-days found by Wheel Impact Detectors) or built up tread where brake shoe material builds up on the tread of the wheel diminishing the depth of the flange. Cracked and or broken wheels are also a reason for changing the wheel set.
Roller bearings are not serviced in the field - if there is a defective bearing, the wheel set is changed out. The defective wheel set would be returned to a 're-manufacturer' which could be a company's own shop or a 3rd party vendor.
That's kind of what I expected, a friction bearing would have to consistently outlast the wheels and not be subject to catastrophic failure before then. Bearings that don't consistently outlast the wheels would be a maintenance headache. The other issue is that the article implied that the sleeve bearings had more friction than roller bearings, which would discourage adoption.
BaltACD The expected bearing life on freight cars is until the wheel set needs changing because of wheel defects, ...
The expected bearing life on freight cars is until the wheel set needs changing because of wheel defects, ...
That's even easier to understand than sorting out the dollars and cents.
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