Gearmotor that freewheels when stopped?

Designing a specialized door mechanism that can be opened or closed via a manual crank or by motor power controlled via raspberry pi. I want the motor’s resistance on the manual operation to be at a minimum. The system is designed via a rope/pulley setup and the crank/motor pulls the ropes.

Options I’ve considered:

  1. A motor that applies just enough friction to run but can be overpowered by crank
  2. A motor with a solenoid…still looking for the right type/size and how to encorporate that into the system
  3. An electrical clutch like this one (a bit expensive and maybe overcomplicated)

I feel the ideal setup would be a gearmotor that just naturally has a neutral stop.

You can probably tell by now I’m a DIY maker and not an experienced engineer so any/all help much appreciated.


Hi alexezorsky,

Welcome to the Tech Forum.

There may be a better way, but have you looked for something like a car starter motor? It comes with the solenoid, gear engagement, and return spring mechanism already integrated, so the mechanics of that part are already taken care of.

Your option 1 is also plausible, but you may have to find a crank with a significant gear reduction to gain enough torque to do the job. The main drawback there is that it will take more turns to move the door than would be ideal. It would almost certainly be the simplest way to go.

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Thanks David!

I actually did think about a car starter! Those things are beasts though. I would also need to find a gear that meshes with the tooth properly. Was hoping for something more power-drill levels of beast-ness. thanks though!

Perhaps you might be able to go with a smaller one, such as might be used on a riding lawnmower or ATV. You’d still have to figure out the gear tooth issue, however.

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Adding to the starter motor options, add a straight piece of gear track on the door and you can buy a gear for the motor to run in the straight piece. I have a link here with the type of straight gear track in mind. MAtch the pitch to that of the starter gear and solid lifting/lowering option.

Boston Gear Rack, Steel, 20 Pitch L509-6 | Zoro

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HI alexezorsky,

You could also consider autodisconnect clutch, such as

(not sure if that works for both torque directions)

Also electric bicycle solutions may offer some ideas.

heke, AsamaLab

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