Simple entirely mechanical speed controls

Sam Salvati

Sam Salvati

I wanted to start a thread bouncing ideas about simple mechanical speed controls, variable or step pulley switch type stuff for use on grinders and such.
 
Have you thought about a cone drive. Used to be some cone drive generators around on a few boats. About 5KW so I know they would run a grinder. As the cone was moved over on a drive wheel the speed was changed by the diameter of that part of the cone
 
I have a NWG with a step pulley set .Don't know if this is really what you mean but my motor mount is hinged so I just lift up the motor which gives me plenty of slack to swap the belt to the next step on the pulley
 
My Powermatic 1200 drill has a variable pulley system, my bandsaw also in a smaller form, not sure what they're called. Essentially it has a big thick belt run between a pair of two part pullies that squeeze or open up by the turn of a lever, raising or lowering the rpm. It's quick and responsive, very effective.

I'm guessing these systems were pretty common in the middle of the last century, before common vfd availability.

I can take a pic if what I'm saying doesn't make sense, I've got the cover off the drill already.
 
Here's the control on the front, it has speeds listed to correspond with three motor rpms, turning down slower puts pressure on the top front pully plate and squeezes the belt out to a wider radius, and contracts on the other side, which I think is just spring tensioned and driven off the motor. Turning up the opposite. The belt is a big thick V belt essentially, which geometry is necessary for this system to work.

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Here you can see it running at about half speed:

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It takes a little push to turn the rpm down, and practically turns itself when you turn it up, otherwise its basically as easy and responsive as a vfd.
 
I think some scooters have a CVT. I do not know how difficult it would be to set them up to manually change the speed.
 
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