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Tapered needles?

Tapered needles?

Tapered needles?

This isn't actually a driveline question, but it concerns roller-element bearings, so I'm guessing that members of this forum have the appropriate expertise. Nor is it a "need to know" question- just trying to learn something.

An ad for Crower's latest roller lifters mentions "polished and tapered needle bearings". Huh? As I see it, a PAIR of tapered-element bearings (complete with races) would be required for such a configuration- but with a roller wheel of no more than 3/8" width, I can't believe there's enough room. So... not being a bearing designer, I wonder if they are referring to nominally "straight" needles that are shaped with a tiny amount of taper near their ends?

RE: Tapered needles?


I believe they meant "crowned" rollers not "tapered".  The "taper" on a crowned roller would be a very slight lengthwise profile (usually a radius) on about the last 10 to 20 percent of each end.  This prevents roller edge loading under shaft misalignments.  Rollers with a large L/D aspect ratio, like needle rollers, tend to edge load and skew quite easily.

A crowned roller will have less capacity than an uncrowned roller, so the amount of crowning is a compromise between load capacity and misalignment tolerance.

Hope that helped.

RE: Tapered needles?

I am not aware of the bearings in question and roller bearings is not an area I know a lot about.

To my knowledge, Bruce Crower retired quite a few years ago. Bruce was a real racer and a gifted engineer who made excellent products and some insightful developments and built a business with a strong reputation for real and worthwhile innovation and quality.

When he retired, his daughter gained control. I think she has no engineering ability whatsoever and has a marketing or management degree. Since then, Crower has been more into spin and marketing hype than innovation, at least in my opinion.

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RE: Tapered needles?

I think part of your stated concern is axial loads, no matter how small. They must be guided, at the very least.

I suspect needles and rollers are always made with a subtle crown these days.  A carefully crowned profile can reduce the deadly edge loading to the point the bearing's load rating is better than a "straight" roller would be, even if perfect alignment was attainable.  

For a few decades Harley used cylindrical, square cut rollers.

Sometimes the crankpins would initiate spalling at the roller edges.

By the 70s Harley had moved to fewer (17 per row from 19?) crowned rollers in aluminum cages. I don't recall seeing any edge spalling, and fewer failures overall. No idea hat's inside the EVO and TC motors.

RE: Tapered needles?

Thanks guys. The consensus seems to be that Crower meant to say "crowned" needles.

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