Any guesses?

[KenSandyEggo]

"What is your output torque requirement? What is your average RPM requirement?"

I was asked this question while inquiring about a part for the prerotator. Of course they don't know what it's for, but does anyone have a good guesstimate of the torque on the inner cable and the average rpm? I turn 2,000 rpm at 220 rrpm, but I don't know what the small pulley-wheel/inner cable is turning.

[StanFoster]

Ken: Divide the driving pulley..(engine) by the driven pulley..(prerotator) and multiply this times the rpm's of the driving pulley.

Anyway...just compare the diameter of the driver pulley..(engine) to the diameter of the driven pulley. The circumference is a direct function of pi...and pi can thus be not considered. Just the ratio of the diameters of the driving and driven pulleys.

Just picking figures out of the air.....if the engine driving pulley is 12 inches in diameter....and the prerotator pulley which is the driven ..is 4 inches....then divide 12 by 4..and you will have the prerotator pulley spin 3 times faster than the engine pulley considering there is no slippage. Just to take it to the other extreme....reverse the above pulleys making the engine 4 inches,,,and the prerotator 12 inches,,,divide 4 by 12...and then your prerotator will spin one third the engine pulleys rpm's.


You of course need to know what your drive reduction ratio is off your engine rpm's ....then you can compute your driving pulley rpm's.

If your engine is running at 2000 rpms'...and your reduction ratio is 2:1....then your driven pulley is running 1000 rpm's. From this driven pulley rpm figure...you can go ahead and derive your final prerotator rpm's.

Note...I am not good at putting into english some of this stuff....so.....interject lots of hand jestures etc..in the above post to extract more info. :D

Stan

[KenSandyEggo]

Thanks, Stan. The info you just posted is a wealth of info that I was totally in the dark about. I mean I knew that a smaller puilley driven by a larger one turns faster, but that's about it. Thanks, and I'll put into practice your info today and see what I come up with. Anyone have any ideas about the torque applied to that prerotator cable? I'm making a WAG of about 30-50 pounds if you ease it in very gently. Sound reasonable?

[Harry_S.]

Sorry Ken.

No help from this corner.