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I know that for a typical dc permanant magnet motor, there is a quadratic relationship between the power and torque,the same goes for power and speed. The max power occur at 1/2 the stall torque,this is also true at 1/2 the no load speed.

Can someone please tell me what is the difference between a constant torque and a constant speed motor? While choosing the right motor for an application(in my case a motor powered screw jack), I only look at the motor's power rating,voltage,max current,stall load and no load speed, i did not see in catalogs for dc motor, whether it is a constant torque or a constant speed motor.

Thank you.

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# Electric motor question(torque and speed relationship)

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