Mechanos
Veteran Member
...The problem with 5v or 8v is achieving the right ratio with the shaft sizes I am dealing with. This is also a problem with chain.
Adding a full compliment (up to 10), of 3v's is not cheap either. That would only yeild 28.8-~30 HP.....similar to the #80 chain.
This engine has a 2" dia. output shaft. That limits the selection of the small pulley due to it needing a 2" bore. This 2" shaft requirement causes the sprocket/sheave, in the higher HP stuff, to become larger. The bigger the driver ....the bigger the driven needs to be to get the ratio. The smallest #80 I could locate is 13 teeth, and A 36 tooth or larger #80 or #100 or whatever, is not cheap although I did find one in #80 with 38 teeth and the 1-3/8" bore that will fit the 1-3/8" PTO shaft.
A 10 groove 3v in 10.6" is also hard to find cheap...
Is there any reason why you can't obtain your reduction using multiple steps instead of trying to do it all in one step? You could run a 2:1 reduction to an intermediate shaft that drives a 1.5:1 reduction to final drive at the pump. That would give you the 3:1 reduction you're looking for at the pump and might be easier to find those ratios in the sizes you need. Just throwing out another option.