N Cook wrote:
b wrote in message
oups.com...
N Cook ha escrito:
b wrote in message
oups.com...
N Cook ha escrito:
Back to the original problem.
The belts had dropped off, obviously perished.
Now , sometimes, on using the power take off to slide up the head

both new bands and cleaned pulleys. moving from REW to play causes the
band
to fall off, presumably due to a snatching / breaking / imbalance
associated
with this double connection to the tape presumably at take up.
If I put in a guide then it can't fall off and will presumably self
centre
back up the vague hump on the periphery of the "reverse" flywheel.
On baluster/ bulbous motor pulleys they usually have a preventer disc
either
side of the bulging active part. This pulley has a larger pulley on one
side
but nothing on the other in the way of a preventer.
Hmmm....if thers no sign of there having being a preventer in the
past, i'd be inclined to think that the belt is not the correct
replacement - too slack?? It should be albe to withstand the change
of tension without slipping or wandering.
-B.


No signs of any preventers removed.
I think its the other way round. The one I replaced it with was a bit too
short/tight as you would normally do, it is probably highly critical. The
problem point is at moment of power switch on so the trailing pulley is
static, so inertial slack in the belt . The force in the belt to pull it
down the vague hump is higher than the differential force at the hump to
push it to the maximum part of the hump it would seem. If it rides down
initially to the axial paired larger pulley then no trouble but if it goes
the other way it falls off.


Have you checked for slight wear in the bearing of the shaft with the
barrel shaped pulley? Is the new belt the same width as the old one?

Ron(UK)