Re: Timing belt drives

"Clare Snyder"  wrote in message news:90c5djpacm2j9ob6qjt6dhthcnvqab1e87@4ax.com...
Any of you guys have experience with timing belt drives? I need as
compact as possible 1 1/2:1 reduction from a 600 rpm  2.5HP engine
(3600 crankshaft RPM with 6:1 reduction) then another 1 1/2:1 after
that (so lower speed higher torque) ( total reduction 13.5:1).This
will be driving a 20 inch diameter 2 inch wide tire/wheel.
How wide and how large do I need the small sprocket? For simplicity I
would likely like both stages identical. This simplifies everything
including tensioning
Small sprocket on output shaft  driving large sprocket on jackshaft
turning small sprocket driving large sprocket spinning on output shaft
of the engine/gearbox  with wheel attached to that sprocket. Distance
from center of small sprocket to outside of large sprocket cannot
excede 7 inches.
Is this possible/feasible???
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I've designed only vee belt drives. Drive belt manufacturers provide detailed design information on line, which I studied after my guesses with parts already on hand failed. I hadn't adequately accounted for the high peak to average torque ratio of a one cylinder 4-stroke gas engine.
Vee belts have the advantage of being able to slip by engaging the idler clutch pulley gradually, to accelerate from rest. On my bandsaw mill the ex- motorcycle wheels need several seconds to get up to 60MPH. The $99 HF engine may stall during engagement unless running about half speed.
On an old Maytag washer the vee belt slips for quite a while as the drum spins up to speed in the rinse cycle. It's a special belt, a standard one with exposed rubber grips too tightly. The motor slides against springs to let the position of the separately driven water pump control the drum belt tension. Pushing the motor inward to loosen the belts reduces its starting current surge to let a 3KW generator run it.