FIRST Climb for 237

[Ted Boucher]

Originally Posted by MetalJacket

Wow, that looked awesome! Would you guys mind sharing how your arms are powered (motors, reduction, etc.)? My team has a similar design but we've been having issues with our gears skipping (I may post more info/pics in a separate thread later if we can't solve it).

Sure.

On each grabber we have 2 - AndyMark 3 Stage GEM Gearboxes (am-0401) each powered by a large CIM motor. Each GEM drives a 20t output gear (am-0186) and both drive a 45t gear (am-0185) between the GEMs. Outside of the gearbox, we have a hex broached 17t #35 sprocket that drives the 30t #35 sprocket on the grabber. This last sprocket section allows us to adjust the ratio and keep within the space limits. If I remember correctly.. thats a total reduction of 195:1.

We had an issue with chain slip and we ended up designing beefy chain tensioners. These tensioners serve a dual purpose of holding the gearboxes in place and eliminating chain slack. A 1/2"-13 threaded rod pushes a "U" shaped aluminum block into the chain path. This is not the best thing for the chain, but we would rather change chain then fix a fallen robot. I will post a picture later today of this system.