pic: 303 Prototype Sheet Metal Drivebase

Honestly, the gear setup of this drive reminds me a bit of the one my team built this year. This is a slight variation on that design, which I’ve been working on in the off season…

http://s11.postimg.org/brxj9hi1b/Arc_Drive_Base_12_WD_V1.jpg](http://s11.postimg.org/jko71go0j/Arc_Drive_Base_12_WD_V1.png)

This is our second time we’ve built a gear-drive system and we’ve been quite happy with it, even more-so since VexPro has made building them so easy. Here’s a few things we’ve liked about gear-drives from our experience:

  • Durability
  • Unlike chain drives we’ve built, this years robot had zero failures in the drive system. After 3 competitions and a little cleaning the gears on our robot this year still look brand new. Maybe we’re just bad with chains, but we’ve yet to build a chain-drive robot that can claim such durability.
  • Size
  • Gear-drives can be made to be much more compact then chain or belt drives since all the force can be transferred on one line of gears (unlike with sprockets or belts which require 2 sets of sprockets in most configurations on >4 WD robots)
  • Pushing Power
  • I can’t speak for all gear-drives of course, but in our experience we have yet to find a robot that could not be pushed by our gear-drive robots (Though part of this we believe stems from the wheel positioning, not just the gears).
  • Ease of Maintenance
  • Unlike a chain or belt drive which requires taking apart the drive module or de-tensioning the drive. Wheels on our gear-drive can be removed by simply pulling out the clevis pin axle and dropping the wheel out the bottom of the drive. Assuming there’s a replacement ready, a wheel swap can be done in less than 30 seconds (not counting the direct-drive wheels of course which require a bit more work). That said, the only time we’ve needed to change wheels was due to tread wear.
  • Efficiency
  • I’m not qualified to speak to the science of this, but based on our experience we’ve found that our gear-drive robots seem to have far less friction in the drive system. I suspect this may be due to the lack of tension in a gear-drive system (or, again, we could just be bad at making efficient chain-drive systems).

Now, of course, the big downside to gear-drives is cost, it’s certainly much cheaper to build a 6 wheel chain drive than a 8+ wheel gear drive. Recently VexPro has made it substantially cheaper and reduced build times compared to when we had to either build or buy all of our components custom made.

All that said, unless the next game challenge prohibits it (or makes it undesirable) we plan on using a gear-drive again next season.