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I'm looking for a solution to selectively engage and disengage a drive shaft with a number of output pulleys, one-at-a-time, like a clutch. Speed would be around 1000 RPM, and torque less than 20 inch-lbs (about 2 Nm). Clutching must happen when unpowered.

My first thought is to emulate how a manual transmission gear selection works (with a dog clutch and a yoke), but a quick google search doesn't turn up any packaged solutions that do this, which leads me to believe it may not be a popular solution to a common problem for a good reason.

How are these sorts of things usually done in mechanical systems? If you have one source of power and multiple powered devices which may be on or off, how are they engaged?

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Tight or loose belts is one possibility, used on shaft drive to drills and lathes for years.

Or consider the electromechanical clutch used on cars now to drive the ac compressors.

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  • $\begingroup$ I was thinking of belts too, but at 1000 rpm, I wonder if the residual friction on any loose-hanging belts would wear them too much. Regarding electromechanical, I'd rather avoid using electricity if possible. $\endgroup$
    – PProteus
    Sep 8, 2020 at 14:19
  • $\begingroup$ belt clutches like this use a pivoting arm to hold the disengaged belt away from the pulleys, so it won't rub the pulleys and get hot while clutched out. this is common on belt-driven riding lawn mowers. $\endgroup$ Sep 10, 2020 at 4:27
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A complicated solution would be an electromagnetic clutch; essentially a solenoid with a spring and a friction wheel. When it's powered, spring is compressed away from the friction wheel and desired pulley. Power is provided and the spring returns to it's unloaded position and engages friction wheel with the pulley. You would need a controller to manage which clutch is engaged.

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  • $\begingroup$ That's a bit complicated for what I'm trying to do, and I'd like to avoid electricity if possible. As mentioned, there must be common solutions for this, like in farm machinery. $\endgroup$
    – PProteus
    Sep 8, 2020 at 14:21
  • $\begingroup$ @PProteus farm machinery, yes hydraulic-electro-mechanical clutches... and they are used to change gears as well... BUT if you don't want complicated. $\endgroup$
    – Solar Mike
    Sep 8, 2020 at 15:12
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Way late, but if you're still interested, or maybe this can help others, look for "Line shaft" or "jack shaft" old factories, water power, etc.

Essentially all factories were driven by waterwheels back in the early industrial revolution. The rotational power from these waterwheels was harnessed throughout factories with line shafts, sheaves, pulleys and belts. Belts could slide off to disengaged sheaves or levers could move the sheave to reduce the axel distance to the line shaft, thus loosening the belt and disengaging a particular machine.

This has some good info, but look around for others. https://www.core77.com/posts/58982/How-Did-Factories-Get-Power-to-Their-Machines-Before-Electricity

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  • $\begingroup$ Isn't that what I referred to in my answer? shaft drive... $\endgroup$
    – Solar Mike
    Sep 22, 2022 at 10:31

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