[mbenard]

Toolin,
How fortunate I was to find your thread. I am adapting the MDT #OEM-190-032 42" blower to my Bolens. Because my PTO is a drive shaft I have been trying to calculate the speed to run it at (18hp with motor speed 3600rpm, PTO output speed 2000rpm). I did not have all thee pullies of the original drive system and removed the angle drive box to connect directly to the impeller shaft. Using the parts manual, without information on the starting PTO drive I came up with a .53 ratio equating 1908rpm @3600 on the engine, close to the 2000rpm of my PTO output. 100rpms I don't think would be a problem but if the .41 is correct I'm now at a 500rpm difference, maybe or maybe not a problem. And using your formula above (same impeller radius) the 2000rpm equals 6280 ft/min, snow may end up in the next county.

I have also Frankenstiened the front of my tractor to make a John Deere like quick-Tach system with hydraulic lift (hydraulic circuit diverter on the dash). I am also making the chute direction control electric with the motor out of a 96 Silverado door window regulator and a toothed ring from the Bolens single stage blower chute (perfect match to the gear on the window motor). I'm having parts plasma cut at a fabricator now (all worked out in AutoCad). Unfortunately I won't have it ready to finish out this season, but look out next year!

 

[mbenard]

Tudor,
That's what I was afraid of because of the direct connection. To bring down the tip speed to 4500ft/min would require throttling down almost of third of my motor rpms, a reduction in power I don't think I can live with. So, I will machine a new larger pulley for the PTO shaft to a speed that will give me the 1450rpms required to make 4500ft/min at full power. Since this tractor is only used for plowing and blowing snow, I don't have to worry affecting any other attachments. The old Bolens single stage blower is just not up to the volume of snow (especially wet) and the mounds the county plows leave at the end of my drive way, hence the move to a two stage blower. It worked fine for the snow load we had in Oakland County (Detroit metro area), but up here next to the lake, and the fact that it is just plain worn out, it needs to be retired.


Mark

 

[mbenard]

Just as a FYI, in checking the new clutch for the PTO, the pulley on it is 4" vs. the 4.5" on the original clutch, which is failing (hope it makes it to end of season). The pulley on the PTO shaft is 8.5" which would have required to be upsized to 11" to work, it would have been tight but would work. With the new clutch, the pulley on the PTO shaft only needs to be 10" for an output speed of 1440rpms at full motor speed, much more workable. Problem solved!

I love it when a plan comes together!
Mark