RC guys are smart, maybe powertool guys are smarter

[lepton]

So with the pins removed the transmission can happily transmit torque in either direction? If so, that's great news.

 

[John in CR]

The transmission does have "no back drive" pins, but they can easily be removed. I've used these transmissions before in hobby robot aplications.

Ted,

So what do you think, will they hold up, or prove to be something requiring replacement after 100hrs of use?

John

 

[Ted_Z]

I doubt any of the dewalt transmission installed in robots will ever see 100hrs of use. However they do see a lot of shock load, and rapid changes in direction. The transmission has 5 planet gears per stage and a steel ring gear (unlike cheap drills which use plastic or pot metal ring gears). I'd say you would be fine putting 500W continuous through these transmissions.

I was able to mate a #35 sprocket to the output by tapping the bore for a 1/2-20 thread and using the left-handed thread screw that holds the chuck on. In fact I think I've got 2 sprockets and one transmission assembly burried in my parts pile if anyone wants to experiment. Here's a old mid-build picture of a robot that used the dewalt motor to swing a hammer.
http://img171.imageshack.us/img171/8063/hshv4.jpg

 

[lepton]

Does anyone know exactly how noisy these things are? If it's gonna sound like a loud power drill running all the time, that might be a big downside...

 

[John in CR]

Does anyone know exactly how noisy these things are? If it's gonna sound like a loud power drill running all the time, that might be a big downside...

Any very high speed motor is going to make some noise, and almost any gearbox mated to it will add to the noise. If you want the silence of a hub motor, you're left only with hub motors or lower speed motors with belt drives. To me silence is a double edged sword, because it increases your accident risk since they can't hear you coming.

I do have some wheelchair gearboxes that are virtually silent, but they aren't rated to very high rpms like most wormgear boxes aren't. They don't turn very freely either, so I expect there's a lot of losses in them. I have one mated to a 17krpm powerpack motor that I've yet to install, so the wheelchair geardown of 24:1 is almost perfect for a bike size tire. The whine of the powerpack motor is impressive though. We'll see how they both hold up, powerful but unlikely to be durable or efficient.

John