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paull

changeing pulley size mower to make blades faster

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paull
-->jackl here-I have noticed that the mower blades on the newer tractors seem to turn some what faster and apear to cut even better. I realize the newer Simplicitys have more horse power but would it be possible to change the pulley size to increase blade speed. If so which one? And how much larger? Has anyone ever done this? If so what were the results? Would a 10 or 12 horse be able to handle the extra load? Just call me curious. Thanks for any input that you might have-->jackl-->:)

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Guest
Jack yes you cna change the pulleys to inclrease the blade speed. On some of the commercial units the blade speeds are higher. This allows for faster ground speed when mowing. Deck blade speed is regulated by OHSA at 19000 FT per minute. In order to keep the tip speed below this the manifactures keep the spindle speeds down for legal purposes. To modify the speed could result in legal problems should someone get hurt. One of the problems of higher blade speeds is they tend to throw material harder and futher. I suppose you could change the pulleys to make the thing turn faster but you are taking a chance that should someone get hurt you would be liable. I am not a lawyer but know that if you modify a unit then you become liable as a manifacturer. My advise is leave it alone. It was designed to work at a certian speed and should do a good job at that speed.

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Guest
When considering blade speed, is it governed by RPMs? If so, can we assume that the blades on a 48" and 60" deck, say running on a Sunstar w/engine speed at 3600 RPMs, rotate at the same RPM? If that is the case, then the tip speed of the 60" blade, if all else is equal, would be faster than the 48" blade, thereby giving a better cut. Where am I wrong? Should we be buying 60" decks for logical reasons rather than "they make it, therefore I MUST have one!!!!!"

Bill

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Fred
Bill,
It's all done with mirrors, or in this case, pulleys. The three different mower gearboxes on any SunStar deck all have the same ratio, a 3:2 overdrive. And the drive pulleys on them are all the same. But the arbor pulleys are different diameters for all three decks, 42", 48" and 60". It all relates to the OPEI/CPSC blade-tip speed rule. "Thou shalt not exceed 19,000 feet per minute." Want to sling a blade through your neighbor's window? Just put arbor pulleys from a 42" on a 60"! Your deck will REALLY 'hum'! (If you can find a belt to fit.) Of course, a bigger deck is like 'more power', gotta have it! Ooh, ooh, ooh!
Now if I can just figure out how to hook up another 60" as a wing mower ...
"One-pass-and-I'm-done Fred"

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dlcentral
I've got a 7' gang mower assy. for you to pull if your "Spot" can tow it. Then you can be called:"One Pass and I'm Done gangmaster Fred!!" dlc PS. Kent is right- too long on titles son! :><><

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Fred
Shrt nf 4 U? Jst ansd Bll & gv lttl hmr bsds! Dv jst lks t pll m chn. K, tgh gy, lts hng chn frm Spt t 5211 & se wh plls wh! Jst lt m nstll ag trs & dbl wts frst. Lw rng, hydr & dff lck wll kck yr btt!
& U Jck, Ur jst bg nstgtr! ;<)

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Fred
Whas a matta t gy afraid yr spt wont pu a mans size load?? m 5211 mignt pl a lod bu it didn cost me $9k either haha, Hows dat hjack?? brg tha overgn LAWN trc on brudda!! as always dlc

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Guest
Hey dlc, now you wentt and ddone itt yoou gott oooolllllld ffrreiy madd.

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Guest
-->jackl here--> how would it be then if I were to increase the pto drive pulley 1" and decrease the mower deck pulley size 1"? Would this cancel out the increase in blade speed or keep it the same. Or could I just increase the pto pulley a 1/2" and still be safe as I don't beleive the pto pulley is the write size. I measured it and it is a 2and 1/2"dia. pulley. What do you guys think? -->jackl-happyjack<-->

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Fred
Jack old friend, No that would speed up the mower blades significantly. You may turn your tractor into a hover craft. Increasing the PTO by a 1/2" would speed it up a little. Tim

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