somewhere on this site, possible before it was hacked (which means long gone) I described the thing..
I have actually built two of these, in similar fashion. The blue one is faster, quieter. The other one has diesel engine and is slower, but runs cheaper.
Splitter are heavy and have a engine, why not make them self propelled? So, old blue was created from available parts 10 or 12 years ago. It has been changed a few times over the years, 16gpm pump to 22 gpm, bigger engine, larger hoses, bigger return filter, and recently the upgrade oil tank and feed line to pump.
Axle was a isuzu rear end (chevy luv) and a cobbled front end. No suspension, which is why I built a trike. drive valve is hooked into the return line after the splitter valve. This is a incorrect way to do it but it has worked well for years now. I see no reason to change it. Cylinder is a 5" bore 24" stroke, but with a custom kick out set at 18". My beam is a touch flimsy even after adding steel to the web. It still bends some when loaded heavy.
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