[sanelss]

It's a holonomic setup where we have one transmission in each corner of the robot. that part of the design isn't new and had great success with it the past few years. But as you stated could use it on two opposite corners for tank drive or with a straight plate can use it for any other drive as well.

You are correct about the retaining clip, but we've used this same axle configuration last year and never had a single problem with it so as far as i'm concerned it's not an issue. We have a bolt on one side for easy dissasembly(which is a maintenance item and even though we used lock washers we did need to keep checking that they are tight so wheels didn't fall off) but it's worth the ease of access.

While we could reduce the weight a marginal bit by pocketing the plate or making the blocks smaller I don't think it's worth it. The plates provide most of the rigidity of our chasis so pocketing them could compromise structure too much. As it is currently with all the changes(compared to last year), this complete drive chasis(with wheels) should weigh around 20-25lbs which is almost half of what ours weighed last year and most of that weight is the cims.

I mean once you take into consideration what we have here(a 10:1 transmission) ready to be bolted onto the chassis with wheel already attached, it's one of the lightest setups you can have when you take mounting and other interfacing hardware into account of other drive systems.