Can someone explain to me how bulbous/baluster pulleys centralise a belt. And why the belt does not slip off parallel sided , ie non bulbous flywheels with usually no flange on one side. The chances of grime or shine on one side or the other of belt or pulley should easily lead to a belt comming off such flywheels , shouldn't it ?
-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on
It's the crown that is on the pulley. The belt will always climb to the highest point and stay there. It's the same concept that kept those big flapping belts on old equipment like you see on the Walton's saw mill.
- Tim -
When Mercedez change to a new body style in 1981, we were in a 380sel and popped off a couple v belts on a dirt road.
someone explain to me how bulbous/baluster pulleys centralise a belt.
The centre fattest part of the bulbousness travels faster, because its wider, thus pulls the belt more than at the ouer edges of the drive wheel. Hence the belt is pulled towards the fatter wider centre.
As for whats-it-called wheels, the slave ones, the belt position on them depends on the driving wheel, which feeds the relatively slack belt to the secondary wheel.
grime is distributed fairly evenly in practice. But there is normally no slippage occurring between belt and drivewheel, so friction level has no effect. You'd need a very dirty and very slack belt for this to occur.
NT
belt.
flywheels
off
I'm surprised they only seem to fall off if the belt is perished or someone meddling inside the mechanism or as a result of some fault or jam.
I worked on old belt driven VTR's. The speed of the heads was controlled by a magnetic brake. As the brake acted, the belt would creep off center of the pulleys to maintain the correct size ratio for the new speed.
The belt will go to the highest point is where the most tension is.... and the most grip.... the belt will not go where there is no tension or little grip.
most grip.... the belt will not go where there is no tension or little grip.
Why then not simply have two flat pulleys the correct distance apart for optimum tension. Edges would prevent the belt from slipping off. I've seen this in some audio tape decks that are fixed speed.
Edges would cause wear.
Lionel: If they were truely FLAT pullys with EDGES, the belt would bump the edges and immediately climb off the pully. If you look closely at the FLAT pully with EDGES on your audio tape deck that you mentioned, the motor pully surface that the belt rides on is CONVEX so the belt stays "high" centered and does not bump the edges..... I hope that this clarifies things for you.
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