What's the name for a kind of gear that slips over the top of another gear and can drive/turn the gear it's surrounding?
I'm making a handcranked flashlight with my 7 year old. We're thinking of using a stepper motor with a gear on the end from an old printer, something like the one pictured. I've seen this kind of crank flashlight made with just a 'female' gear embedded in the crank handle, that slots right over the 'male' gear (as pictured here). That's the best way I can describe it. What's the name of this kind of gear? One that would slot right over the top of the gear in the picture below and be able to drive it? I can't seem to find what I am looking for anywhere, any ideas? If I knew it's name then I could search for it. Thank you!
Edit** What I looking for is kind of like this internal spur gear (the image below), but with that outer ring FITTING REALLY TIGHT around the inner spur gear, with the number of cogs matching exactly (not like this picture, where the outer ring is really big compared to the inner gear).