pic: Offseason 8W Tank Drive

[Knufire]

Here's the current revision of the drive. The only main differences are the lightened bellypan and less aggressive pocketing on the front/back rail. Any last tips? I've debated elongating the top end rail flanges and possibly putting another flange down the back as 971 does.

Another change (not shown) is changing the outer gearbox bearings from round to hex. This allows the intermediate shafts to be pulled out without having to disassemble the outer drive rail.

[JesseK]

Hmm, 971's bellypan extends to the outer rails. They also have plates on the top of the rails for added strength. Have you considered doing this with your design, at least in the middle of the rails?

I'm no ME, but the proximity of the 4 rivets without any other support raises an eyebrow. The likelyhood of the sheet metal shearing or holes elongating (making the drive not square) seems pretty high.

[Knufire]

Originally Posted by JesseK

Hmm, 971's bellypan extends to the outer rails. They also have plates on the top of the rails for added strength. Have you considered doing this with your design, at least in the middle of the rails?

I'm no ME, but the proximity of the 4 rivets without any other support raises an eyebrow. The likelyhood of the sheet metal shearing or holes elongating (making the drive not square) seems pretty high.

I had a version where the bellypan extended to the frame perimeter. Since the wheels pairs are so close together and the chain hangs below the button of the frame, by the time you have wheel and chain clearance cutouts, you only have the middle section underneath the gearbox left, which makes it significantly harder to access the gearbox.



I've often done two rivets on a diagonal in a 1" square, but not 4. That I pretty much copied from the VexPro Drive in a Day, which I believe is bolted together. I'll definitely consider that.

The dead axles and gearbox shafts should help transfer the load from the outside drive rail to the inside drive rail on a hard side impact. Also, the plan for superstructure mounting is a 2"x1" box crossbar, which should help as well. I'm thinking about ways to mount the bumper that would increase the strength of the frame, as 33 does.