Does this type of motor exist?

Hi all,

I don’t know much about motors and am looking for a DC or AC motor for a project that does the following:

  • has a normal motor mode (ability to control direction and speed of rotation)
  • is able to switch into a free swivel/coast mode with low friction

The motor is for a simple mechanism that allows a pendulum (a rigid rod) to be remotely “swung” up to some angle (perhaps with Arduino) through a motor locking itself to the swivel point, then released (i.e. “unlocked”), allowing gravity to take over and the pendulum to swing freely. I imagine there would need to be some ball bearing involved to reduce the rotational friction in the unlocked state.

Any and all help is greatly appreciated. I do have a bit of a budget for this project so cost isn’t a huge deal.

Thanks so much!


As opposed to a particular kind of motor, it sounds like you just need a controllable clutch that you can add into your system. Unfortunately though, I do not have any suggestions for where you might find that.

Alternatively, you might be able to achieve what you want using a stepper motor along with a driver or controller
that you can use to deneergize the motor, allowing the rotor to spin freely. Going that route would simplify your mechanical setup, though I would expect the stepper motor rotor to add more rotational inertia to your pendulum than the clutch mechanism when the clutch is disengaged.

- Patrick

Do all Pololu stepper motors spin freely with low friction when not powered (i.e. there is no electromagnetic brake)?

Our stepper motors do not have electromagnetic brakes.

- Patrick