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Unread 19-12-2013, 20:14
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Re: combined free speed of 3 motors

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Originally Posted by DuaneB View Post
Are the motors tied together in a gearbox
Yes.

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If so, there isn't really a free speed. Free speed means there's no load on the motor.
Free speed in this context means "no load on the output shaft of the gearbox" (and ignoring friction in the gearbox with no load on it).

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The maximum speed of the system, barring additional loads, will be somewhat less than the lowest free speed of the three.
False. It will be somewhere between the slowest and fastest.

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Whenever you're ganging motors together, you want their free speeds to be as closely matched as possible, taking into account any difference in gearing.
The equation shown works whether the individual free speeds are matched (with a speed reducing gearhead on the faster motors) or not. If speed reduction is used on any of the motors, then use the Free Speed and Stall Torque of the gear+motor for that motor.