Jerry, thanks for your help brainstorming on this one! I think the Wooldridge power unit should be good for 2 esc, 1 rx, some sub-C nimh, pilot light, driver. Then the attachment can carry servos and actuators as needed.
Blender, thank you! Planning to keep it all fairly simple. The vintage stuff usually speaks louder to me. I keep reading about people saying Wooldridge equipment was ugly, but i think it's distinctive.
The biggest challenge on this is finding axles/trans, I need seperate control on each side because drive & steer. These are an "Overslung" machine so think like a Tractor minus the front axle, and only steering using cutting brakes. A computer TX can mix the drive & steer channels tank-style with offsets -100% / +100%, and be all happy happy, but that's for later. I didn't like the idea of massive servo trying to wrestle it around corners since they didn't use hydro-steering yet.
I started this project assuming i'd use a Heiliner power unit, it has a narrower frame width than the Wooldridge.
I picked up a pair of "jsx-370" gearboxes in "90 rpm" to test out. Good form factor, bad setup. Reordered those around "23 rpm" and did motor swap below.
Shaft couplers to adapt D-shaft to Wheel
https://www.amazon.com/gp/product/B0..._title_o00_s00
Gearmotors
https://www.amazon.com/gp/product/B0...0?ie=UTF8&th=1
Jungle website sells those 370 gearboxes in several flavors: 3, 6, 10, 18, 23, 30, 40, 66, 90,160, 210 RPM
Then there's a questionable review for those with chart they posted as stolen from ebay, claims gear ratios:
40, 65, 160, 200, 260, 340, 600,1000 (xx to 1)
Sketchy chart says 90rpm = 65:1
Started thinking something 200:1 (30), 260:1 (23), or 340:1 (18) sounded much more likely numbers for dragging 10+ lbs of truck, some dirt, maybe another truck
I also remembered the Redcat Everest-16 rock crawler that was a donor for my Structo Dump originally had a 280 / 370 motor. So ordered pair of Redcat 'RC370' 28026N motors.
Redcat motors are a direct swap into those jsx-370 series gearboxes.
Mount screws in the first set were originally installed with "very much" red locktite, assume the need for heatgun or soldering iron to break hardware loose.
Brass worm gears are a press fit on rotors, but you can lever them off the original motors with some Diagonal cutters.
I had looked at some of the 6v versions of these gearboxes, and wasn't very impressed with the specs provided using their supplied Silver-can motors!
https://nfpshop.com/product/6v-12v-2...el-nfp-dwg-370
Their 6v 260:1 ratio box coming in at 17 rpm. Then those pushing 4" tires at 1 foot per rpm, i can't really see being satisfied with this equipment moving at 18 feet per minute empty, downhill, with a tailwind. Yeah. The rc hobby can build WAY better motors than that.
4" diameter tire has 2" radius = 5.08cm. Gearbox spec sheet lists Max rated Torque at 25 kg-cm. So i think that's like 5.08kg at tire tread.
My RC motor swap in the 260:1 boxes got enough torque that a 4" wheel doesn't want to ponybrake by hand, and got a reasonable top speed of around a slow walk. Because large 1940s off highway equipment suspension was sidewall flex, and they aren't paying my driver to get beaten up or break stuff on the machine.