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I need to be able to generate constant torque and my first approach is using a DC motor. But, the problem is that I'll need to be able to apply this force in a stalled (static) state or even a reverse state where there is counter rotational torque which is greater than the motor torque being applied to the motor so it is turning against its own torque but just resisting the external torque.

I know that most DC motors would be prone to overheating in this condition. Is there a better option?

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  • \$\begingroup\$ Without forced air cooling you need a motor with >10x torque operated at <10% of the rated voltage which may be slightly less than rated current . Torque can also be increased with ratiometric pulley wheels . DCR controls stall current and is often 800% of rated current. Then you have the problem of commutator position and bridging arcs. A large stepper motor with gear belt pulley might be a better solution if you can control it correctly. \$\endgroup\$ May 6, 2017 at 0:50

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A motor that can provide torque continuously or for an extended period of time while stalled is, by definition, a torque motor. Torque motor designs can be implemented using various types of motors, both AC and DC. The design could result in a motor that is physically larger than a continuously rotating motor with the same torque capability. The design could include a separately powered cooling fan and other cooling enhancements.

If the motor needs to prevent the load from possible movement in either direction, speed and direction sensing would be required.

A servo motor and control system may be required, depending on the overall requirements. Servo motors can be provide performance similar to torque motors in addition to position control. Various types of AC and DC motors can be designed as servo motors.

To determine what is the best option, you need to consider every aspect of the requirement including detailed duty cycle, environment, speed range, accuracy requirements, actual torque and speed requirements, number of units required, available budget, expected useful life of the equipment, reliability requirements and probably other factors.

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It sounds like you want a torque motor. These can run indefinitely while stalled.

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  • \$\begingroup\$ These tend to be weak torque. \$\endgroup\$ May 6, 2017 at 0:53
  • \$\begingroup\$ Thanks.. Sorry the previous answer just beat you to it. \$\endgroup\$
    – mxc
    May 6, 2017 at 23:30

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