Thanks to SARE for making this project happen.
CAD modeling by Paul Trieu.
Build by Andy Mazur, David Brustlin, Scott Gallant, Jean Donohue, and Grant Schultz
Illustrated CAD plan should be most valuable...get your hands on a bunch of 2x8 and 4x4 lumber and lots of quality carriage bolts. Critical pieces detailed below.
First, let's begin the shopping list...
56C 40:1 right angle gear reducer (speed reducer) with either one or two output shafts.
56C describes the motor and gear reducer combo you'll be putting together. A '56' Frame electric motor has a 5/8" output shaft, and the 'C' designation means it has a machined face tapped with bolt holes for mounting to a gear reducer. You'll only use one output shaft, but dual-output gear reducers are common and this flexibility will aid in ease of sourcing. Gear reducers are near-bulletproof and would be expensive to purchase at retail, so eBay is a great source. NOS (new original stock) industrial components often end up on eBay after languishing in a warehouse for awhile. Expect to pay $75-150 for a good condition gear reducer. One reason to seek out NOS instead of used is that the oil seals on output shafts are likely in better condition. We don't want oil leaking on our produce, do we?
56C 1/4-1HP electric motor
Anything in this range will work, just make sure the gear reducer can handle the input HP. All motors and gear reducers have an information plate on them. Purchasing a pre-assembled motor+gear reducer on eBay or elsewhere is an easy way to achieve compatibility.
A length of double-walled plastic drain culvert. 30", 32", or 36"
You'll need at least three pieces, at least two of which are 3 ribs or more long. (one channel for bolts, the other for unencumbered wheels) Have some 30+" old tractor rims? That may work too. Hiring a good fabrication shop to bend and drill some C-channel into hoops is another alternative. Start talking to excavators, drain tile installers, etc. One trades trash is another trades treasure.
'2050' style roller chain has widely spaced links and does best riding over the long bolts of central drum guide.
Pedal Power Root Washer