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Ron Ron is offline
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Default Flat belt mechanics

On 16/11/2011 13:24, Gareth Magennis wrote:
"Gareth wrote in message

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I don't remember seeing this before. Instead of baluster/bulbous pulley or
capstan, two angled faces with a thin ridge in the centre on the drive
pinion. So the belt must ride on the ridge but why does it not hunt
There is a limiting flange either side of the angled flats and the width
the rubber band is greater than the distance between a flange and the
central ridge, but still why no riding about?. Then what I thought was
construction is probably part of the dynamics. The capstan is 2 discs
together but one is 49.94mm diameter and the other 50.04mm so this step
change must make sure the band rides over the ridge but biased to one
lightly touching one angled face, but not touching a limiting flange.
When I
get the mechanism working again I will try viewing with a xenon strobe
. Anyone any input on this ? more or less prone to changes in rubber
restitution/stretch etc, more/less likely to come of when PTO is engaged,
greater/less accuracy in speed of drive with varying driven-side back

Thats just reminded me of the DAF Variomatic automatic gearbox.
Here's one working on Youtube.


Oops, wrong link. This one works:


At one time Philips washing machines used a very similar system.