Roller thrust bearing question

I have asked bearing engineers about this in an e-mail with no response. Surely someone here can provide the correct answer. There
are three types of rolling element thrust bearings that I am very familiar with. The first uses balls. I understand how these work. The second type uses tapered rollers and conical races. I understand these too. But the third type uses flat races and straight cylindrical rollers. The load they can take is quite high. But the rollers must skid. Why doesn't this ruin the bearings? And why doesn't this skidding cause high friction? Thanks, ERS
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Eric R Snow wrote:

the ones I've seen have a slight taper on the roller.
John
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Eric They do skid but they can run along time at near rated load with no apreciable wear. I use this style bearing in some very large spinning machines and they have lasted multiple years. The best designs are the ones that torrington used, they use a 2 segment roller where one roller is longer than the other. Then each set of rollers is flipped so that the long one is alternated to top or bottom position. That way they track differently. Some of the ones I use have a 5" ID and a 7" OD with a load capacity of 135,000 pounds. They work their asses off in the machines we use to spin Taper aluminum extrusions into lightpoles and flagpoles. I've got these machine running 15 hours a day 6 days a week now and those bearings are the last thing I am worried about now. The most extreme setup runs with 100 Horsepower on the spindle and nearly 100,000 pounds of force on the the carriage. The machine uses a world war 2 gun boring lathe as the skeleton and everything else is unique. Some day i'll post a picture on the website www.pkpole.com part of the problem with getting information from the bearing manufacturers is that the industry is becoming two companys with all the buyouts. Don't even get me started on how pricing and availability has turned to crap.
Greg John wrote:

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Greg please post a picture and when you do let use know here. You must be very close to the Bridgeport ferry, there are many in this group from the area. I live in CT.

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Greg
Some day i'll post a picture on the website www.pkpole.com part of the problem with getting information from the bearing manufacturers is that
the industry is becoming two companys with all the buyouts. Don't even get me started on how pricing and availability has turned to crap.
I looked at your site. You must have a power bill that has no limit. Care to share? And some pictures would be interesting.
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wrote:

Greetings John, You are correct. The needles, which are 5mm long (.19685"), are .0002" smaller on the inside diameter. The washers (races) are thinner on the inside too. .0002" thinner to be exact. So that adds up to .0006". When I had measured these before I did it so quickly that I didn't notice the .0002" difference. I thought the difference would need to be much more than .0002". Guess that shows, once again, that before I assume something I need to be sure I have all the facts. Thanks, Eric
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