pic: 1918 pneumatic hub concept

[Wayne TenBrink]

The model shown here uses nuts and washers as standoffs. I built a prototype using standoffs between the wheel flange and sprocket that were made of 3/4" OD aluminum bar with a hole bored in the middle. They were about an inch long. It also used a nut between the hub flange and the wheel flanges, and the bolt heads are on the sprocket end of the assembly.

The sprocket shown here is about 27 teeth. The real thing would probably have 36 teeth and be driven by a single stage gearbox (AM CIMple). We would bore out the center hole to pilot the OD of the hub. That would center it and carry the radial chain loads. The four 5/16 bolts and standoffs would only carry the torsional loads.

Another thing - The axle is 3/4" aluminum with 3/8" shoulder bolts at each end. The shoulder bolts tightly connect the axles to the frame rails, which are basically parallel plates (inboard and outboard) with 3/8 holes, spaced and located as needed for ground clearance, quantity, etc. In order to control and adjust center wheel drop, we are thinking of putting the holes at each end of the mid-frame axles off center by about 1/8". By rotating the axle, we could have about 1/4 total adjustment range.

We hope to try 8 wheel drive (4 per side) tank drive, with the pneumatics in the center and skyway or plactions at the corners to improve turning and reduce bounce. We could fit this arrangement into either a long or wide axis.

Of course, the 2011 game could make this all a moot exercise...