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HOWTO - FIX faulty Drive Belt with O-Ring.

 

THE PROBLEM

Projector etc, drive belt wears loose or snaps.

The case written about here is my Sankyo 800 Super-8mm projector. 

 

FIX IN BRIEF

Replace with O-Ring available from auto Brake repair parts suppliers, eg "Brake Service Centre".

The O-Ring needs to be THINNER than the original drive belt and of similar or slightly larger diameter to give a loose fit.

 

 

FIX IN DETAIL

Several friends suggested O-Ring replacements.  I asked at a hardware shop and got directions toan automotive supplier "Brake Service Centre".  This was the perfect setup with O-Rings of various diameters andthicknesses displayed on a self-service display rack.  They cost about $3.00 each and I had the good sense at the time to buy 4 slightly different ones of about the same size as the snapped drive belt which I had brought with me.

 

On getting home, the best-of-4 result was not the one I expected.

3 of my belts gave too much friction and slowed the motor down.

The best-result O-ring was thinner than the original and also quite loose fitting so when running it appears to billow out on one side. But that is the one that delivers smooth running at full speed.

 

The Sankyo 800 had me very puzzled at first as to how to get the O-Ring on because there seemed to be no way

to get it past a worm gear arrangement operating the frame counter. But closer inspection revealed ingenious design to allow for that.  On loosening mounting screws for the worm gears,their white nylon holder slides along and down slightly opening a gap for slipping in the O-Ring.