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I have almost completed a little ZTR rider mower design project with 3D illustrations to find design errors. I may soon build a prototype version. I enjoy 2-cycle Lawn-Boy engines, even though they can no longer comply with EPA rules. I think a 2-cycle Lawn-Boy engine might be a fun and durable prototype engine if a version was produced with a suitably-strong self-propel PTO drive.

I ask those of you who have experience with all Lawn-Boy self-propel drive systems, which do you think would endure slowly pushing a much heavier load? Think of the proposed PTO load to the prototype wheels as being equivalent to a self-propelled Lawn-Boy pushing itself up an infinitely-long very steep bank. If its PTO drive could endure that load, it would push my prototype's wheel driving load. Some Lawn-Boys had what appears to be a worm-drive shaft, driven by their crankshaft. Others had a belt-drive pulley below their engine but above their lower engine mount. Maybe they produced other configurations. I don't know.

I'd mount my prototype's blade directly to the engine crank, just as standard Lawn-Boys do. I'd use Power Take Off (PTO) power to control speed and direction. I just want to know which Lawn-Boy PTO output configuration you guys think would be the toughest and most dependable. I doubt that it's load would ever exceed about 1/3 horsepower peaks. Driving mower wheels, if done efficiently, requires only a tiny fraction of power required to drive the blade(s). Hydrostatic drives are incredibly inefficient! Often over 95% of hydrostatic system input energy is converted to waste heat. So don't be mislead by correct statements about power allocations within hydrostatic transmission driven mowers. That correct information does not apply to this project. If vehicle wheels are not tiny which can cause high rolling resistance, even 1/10 horsepower can push a 250 pound rubber tired vehicle through level lawns at about 3 mph. Maintaining mower blade tip speeds around 1700 feet per minute often becomes a very power-hungry load at those same ground speeds.
Thanks for your help,
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