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

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    Motor Rpm
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Discussion Overview

The discussion revolves around the relationship between torque and RPM in DC motors, exploring how variations in coil density affect these parameters. Participants examine the implications of torque on acceleration and the influence of load on motor performance.

Discussion Character

  • Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant states that torque is the rotational force and questions how a motor can be slow if it has more force, referencing the relationship between coil density and motor performance.
  • Another participant suggests that while torque provides acceleration, a motor can reach any speed, albeit slowly, depending on losses proportional to speed and the mass being spun.
  • A different viewpoint indicates that the increase in torque at lower RPM is countered by an increase in back electromotive force (emf) at higher RPM, which reduces torque at those speeds.
  • One participant emphasizes that motors operate in conjunction with loads, which dictate the RPM-torque relationship, noting that a high torque motor will not produce torque when freewheeling without a load.

Areas of Agreement / Disagreement

Participants express differing views on the interplay between torque, RPM, and load, indicating that multiple competing perspectives exist without a consensus on the relationship dynamics.

Contextual Notes

The discussion does not resolve the assumptions regarding the definitions of torque and RPM, nor does it clarify the specific conditions under which these relationships hold true.

012anonymousx
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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.
 
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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.
 
The increase in torque at lower rpm is offset by increase in back emf at higher rpm, which decreases the torque at higher 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.
 

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