Physics Forums (http://www.physicsforums.com/index.php)
-   Classical Physics (http://www.physicsforums.com/forumdisplay.php?f=61)
-   -   How Can A High-Torque Motor Have Low a low RPM (http://www.physicsforums.com/showthread.php?t=663395)

 012anonymousx Jan9-13 09:01 PM

How Can A High-Torque Motor Have Low a low RPM

Torque is the rotational force.
If there is more force, how can the motor be slow?

I'm building a DC motor and read that given a constant amount of coil, creating a very dense coil will increase torque but lower RPMs.
Conversely, making it looser (bigger radius) increases RPM but lowers torque.

 Simon Bridge Jan9-13 10:07 PM

Re: How Can A High-Torque Motor Have Low a low RPM

The torque gives you acceleration - but it is possible to accelerate to any speed... however slow.

For your motor - it will accelerate to a constant speed due to losses that are proportional to speed. This will be proportional to the amount of mass that has to be spun - and so is the torque.

 rcgldr Jan9-13 11:41 PM

Re: How Can A High-Torque Motor Have Low a low RPM

The increase in torque at lower rpm is offset by increase in back emf at higher rpm, which decreases the torque at higher rpm.

 russ_watters Jan10-13 05:23 AM

Re: How Can A High-Torque Motor Have Low a low RPM

Motors are connected to loads. The load determines the ratio between RPM and torque. If a "high torque" motor is not connected to a load and is just allowed to freewheel, it does not produce any torque.

 All times are GMT -5. The time now is 11:05 AM.