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N_Cook N_Cook is offline
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Default Flat belt mechanics

Ron wrote in message
...
On 16/11/2011 15:05, Gareth Magennis wrote:
wrote in message
...
On 16/11/2011 13:24, Gareth Magennis wrote:
"Gareth wrote in message
...

wrote in message
...
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
about?
There is a limiting flange either side of the angled flats and the
width
of
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
crude
construction is probably part of the dynamics. The capstan is 2

discs
fitted
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
side,
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
light
. 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
torque
etc.




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


http://www.google.co.uk/search?hl=en...omatic+tra ns
mission&oq=daf+variomatic+transmission&aq=f&aqi=g1 &aql=&gs_sm=e&gs_upl=23719
l28672l0l28922l27l21l0l13l13l0l297l1359l2-5l5l0


Gareth.



Oops, wrong link. This one works:

http://www.youtube.com/watch?v=mEK4IVhLqL8


Gareth.



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

Ron



Well I'll go to the foot of our stairs!



Gareth.



Aye lad, they used a plastic[1] pulley containing three ball bearings
fert centrifugal whatnot. If the drum got jammed, the belt would slip,
the pulley would burn and emit the smell most horrible.


[1] Looked like Bakelite but probably wasn't

Ron



Dyson vacuum cleaners have a similar mechanism. An unnecessary football
rattle mechanism in the slip clutch so a disturbingly nasty noise on a jam.
Incidently anyone else find the phrase "No loss of suction" for a system
that forces air down draggy 10 foot of narrow piping, inside the machine,
unlike conventional ones- air in and out over 1 foot if that.