Why can't they use actual bearings?
09-28-2005, 01:00 PM
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Why can't they use actual bearings? Instead of the things they call bearings? I would think with all this technology that these moron engineers could come up with something? If I can come up with it in my head then these idiots should be able to do something? Or am I just some stupid punk who should shut his mouth? Cause my idea rocks!!!! I just wish I had the means to test it.
09-28-2005, 01:14 PM
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Originally Posted by snketr
Instead of the things they call bearings? I would think with all this technology that these moron engineers could come up with something? If I can come up with it in my head then these idiots should be able to do something? Or am I just some stupid punk who should shut his mouth? Cause my idea rocks!!!! I just wish I had the means to test it.
you nailed it!
09-28-2005, 01:20 PM
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There is a needle style cam bearing...
http://www.bopengineering.com/beltdr...c_topend.shtml
http://www.bopengineering.com/images..._bearing_s.jpg
http://www.bopengineering.com/beltdr...c_topend.shtml
http://www.bopengineering.com/images..._bearing_s.jpg
09-28-2005, 01:21 PM
#7
Originally Posted by snketr
Instead of the things they call bearings? I would think with all this technology that these moron engineers could come up with something? If I can come up with it in my head then these idiots should be able to do something? Or am I just some stupid punk who should shut his mouth? Cause my idea rocks!!!! I just wish I had the means to test it.
several reasons.
1. if you had a roller bearing, all of the pressure and force that the pistion is making, would be focused on the little line of contact that the roller has.
2. you dont want metal on metal contact.. that makes friction, and wear... instead, it floats on oil... that spreads the surface area out, and has less friction.
now on the cam bearings, where theres alot less force, yes, you can use roller bearings...and it has less friction
however, they create metal on metal contact, and eventually do wear out... keep in mind, if this big cam journal is spinning at 3500 RPM, then that tiny roller is spinning 35,000 RPM.... NASCAR, Indy, and other 'exotic' high dollar race motors use roller cam bearings..... they also use TINY main bearings... conventional style, but smaller dia.... this is because the smaller the circle is, the less distance around it... so its like its moving slower.. and slower = less friction.... but smaller also means higher wear potential.. once more, why it shouldnt be like that in your street motor...
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09-28-2005, 02:09 PM
#8
Like they all said. Main, rod, and cam bearings actually float the journal on a cushion of oil and because of the large surface area, it han handle enormous stresses. Needle, roller and ball bearings concentrate the pressure on a very small pection of roller that touches the race. Not to mention that roller, needle and ball bearings need a little more play in them, which you dont want in an engine. Id be willing to bet that the first engines were actually prototyped using roller type bearings, but they changed over to the current style cause they work better.
09-28-2005, 02:40 PM
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also the crank would have to be a press-together type. i disagree with the two reasons above, but only becuase motorcycle engines have used them for years (press together cranks). follow me? if the crank didn't come apart there would be no way of getting a roller bearing over the journal surface.
09-28-2005, 02:42 PM
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Two stroke engines use them due to the oil being mixed in with the gasoline and having to lubricate the lower end before getting burned. They cannot rely on an oil film to distribute the load as four strokes can.
Plus think about all of the rotating mass that a needle bearing setup would add to the big end of the connecting rod.
Plus think about all of the rotating mass that a needle bearing setup would add to the big end of the connecting rod.
09-28-2005, 02:51 PM
#14
Originally Posted by stevewix
also the crank would have to be a press-together type. i disagree with the two reasons above, but only becuase motorcycle engines have used them for years (press together cranks). follow me? if the crank didn't come apart there would be no way of getting a roller bearing over the journal surface.
09-28-2005, 04:14 PM
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I know it's a totally different animal but the Honda engines used on pressure cleaners little one cylinder deals ride on two bearings the crank has tapered ends and the case splits. Yeah I know less power and lower RPM's but those damn things run forever and are very efficient.
09-28-2005, 04:17 PM
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No late model motorcycle engines that I've torn apartor know of use roller bearings. All use journal or sleeve type bearings like a car. Some use them at the cams only. An older press together crank was generally welded up in performance uses since it made the crank stronger.
Bearing cost is a big reason sleeve bearings are used. Another is rpm and load. Most high speed industrial bearing applications are sleeve bearings.
Bearing cost is a big reason sleeve bearings are used. Another is rpm and load. Most high speed industrial bearing applications are sleeve bearings.
