Shazaam !!! Barry , you musta gaduated 3rd grade! I didn't, way over my head
Phil Smith
TR6
----- Original Message -----
From: Barry Schwartz <bschwart@pacbell.net>
To: Evans, Mark <Mark.Evans@Anheuser-Busch.com>
Cc: <triumphs@autox.team.net>
Sent: Wednesday, January 19, 2000 4:57 PM
Subject: Drive shaft phasing (sorta continued)
>
>
> > snip> When the shaft is at an angle, the slower spinning
> >yoke half on one end compensates for the faster spinning one on the
opposite
> >side of the other end of the shaft. Did I get that right?
> ***********************************
> Well, basically, yes, the two yokes cancel out the fluctuations if phased
> correctly. And yes I am a mechanical engineer (23 years now). But, the
> yokes at each end of the typical driveshaft don't really rotate at
> different rpm's. Two of the opposing "cup's" linear speed, in feet per
> minute on each yolk, (the ones that change their angle in relation to the
> centerline of the input shaft) do vary in a sine wave manner as it rotates
> for one full revolution, so that you don't have a smooth rotating
> intermediate shaft, but rather a pulsing one. It's still the same "rpm",
> but the velocity (in feet per minute) of each revelation is not constant.
> Constant velocity joints take care of this problem hence the name. I
> usually try to explain complex operations in simpler, easier to understand
> terms and sometimes I get it right, other times I miss the boat. If you
> ever see it in action it's really easy to understand, but it's VERY hard
to
> explain (for me anyway)! Maybe this would be easier to visualize - If
your
> familiar with the old phonograph record or the more modern CD's, when
> spinning at a constant rotational speed (RPM), the distance traveled at
the
> edge (larger radius) is far greater than the distance nearer the center
> (much smaller radius) for a single revolution. If you try to match the
> distance traveled using your finger, you'll find that you have to move
your
> finger at a much faster RATE (higher velocity) the farther away you get
> from the center. The arc drawn through the angled u-joint (cup) is much
> the same. That is to say, the arc traveled at the outer angled cup is
> greater than the arc travelled at the inner cup in relation to the input
> shaft centerline so in effect you actually have a sine wave fluctuation in
> velocity of the two shafts. The RPM or "revolutions per minute" is the
> same, but the RATE at which the two shafts revolve is not. The VELOCITY
> of the input shaft is constant, the VELOCITY of intermediate shaft
> fluctuates (speeds up slows down for each revolution). Stick another
> joint, on the other end of the intermediate shaft at the exact opposite
> angle and it fluctuates in exactly the opposite direction, and viola, the
> output rotational speed matches the input with no fluctuations! Granted
> these fluctuations are rather small in a typical driveshaft, but can and
do
> induce vibration in a driveshaft that can spin upwards of 6000 rpm. An
> axle shaft with a max rotational speed of maybe 1500 rpm isn't affected as
> much-
>
>
> Barry Schwartz (San Diego) bschwart@pacbell.net
>
> 72 PI, V6 Spitfire (daily driver)
> 70 GT6+ (when I don't drive the Spit)
> 70 Spitfire (long term project)
>
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