In a message dated 6/26/2007 9:38:08 P.M. Mountain Daylight Time,
saltfever@comcast.net writes:
Otto: Can rollers really take the abuse in the tail shaft? Have you actually
seen them in there? At 8,000-9,000 rpm of the 2" diameter yoke can you
imagine the speed of the little rollers? Can they get enough lube? It might
work for an 8 second drag race but how about 2-3 minutes of LSR?
I have seen them in a tail housing but it was in a drag tranny. I have
rollers on the cam bearings in my engine but they of course spin at half
engine
rpm. I'm sure the engineers on the list could answer the rpm limits of needle
roller bearings. The trans has ball bearings that spin at engine rpm and they
hold up just fine.
Am I doing my math right? At 8,000 rpm the circumference on a 2" diameter
yoke is traveling 4,188 ft/min which is marginally acceptable. But the tiny
1/8" rollers have to go 16 times faster. (The ratio of the circumferences
between 1/8" and 2" diameters is 16:1) So 16 x 4,188 ft/min is 67,000
ft/min. for the rollers. Yikes!! Or put another way, the tiny rollers
pressing against a 2" diameter object spinning 8,000 rpm have to travel 16
times faster. 8,000 rpm x 16 = 128,000 rpm for the rollers. Holly cow!!
Can they really do that? That is an incredible rpm. -Elon
128,000 rpm for the rollers! I've told you a million times not to
exaggerate!!! LOL
Otto
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