On Sat, 31 May 2008 13:05:52 +0100, "N_Cook"
wrote:

A picture of a random collection of pulleys
http://home.graffiti.net/diverse:gra...et/pulleys.jpg
plastic brass and aluminium for use with rubber drive bands in tape
recorders, VCRs etc. They all have a small groove at the root of the V
section of the pulley. Anyone know the function or reason for this groove?.
All I can think of is it may avoid an aquaplaning type possibility of air
getting trapped under the rubber band snd so wow/flutter possibiliy.

more likely a machining aid during manufacture.
a V point tool cutting on both sides of the V is pretty well a
machining nightmare.
far easier to make a slot then do a single face cut out from each side
to form the V.