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Brettw

Front PTO pulley, new question

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Brettw
Does anyone know the diameter of the pulley on the front crankshaft PTO setup? This would be to run a snow blower on a 7100 series. There is a belt listed under the hood for a front PTO blower belt, but the belt that was on the tractor and the Simplicity belt are different lengths. I want to start by making sure I have the proper diameter drive pulley. Thanks in advance.

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RickS
Brett, Are you sure of the tractor series. It was my understanding the 7100 series used the mid PTO. The 7000 series used the front PTO. That said I don't have the length with me at work. Rick........

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larry8200
Both my 3416H and 7013S have mechanical forward PTO's for running snowblowers. (they have a second PTO handle across from the center PTO handle) My 7100 uses the middle PTO, but I think you could use the mechanical PTO if you had a Briggs single, and there was a electric front PTO too... I'd be happy to measure them if that would help.

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RayS
1690356 is the front mechanical PTO kit for the 900 & 7100 series tractors. Although most used the mid PTO there was a front available. Mine I believe is 6" but would have to check to make sure. It is on page 24 and 50 of the manual below. I am thinking of putting an electric one on like Bill Engle has to run my EZ Rake. http://bsintek.basco.com/BriggsDocumentDisplay/default.aspx?filename=jgEDGP_byN1tG_Exj7mRgtLvBCd6 http://bsintek.basco.com/BriggsDocumentDisplay/default.aspx?filename=jgEBGP_etO7tG5EPa7mRgtLvBCd6

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PhanDad
The outside diameter of the electric PTO pulley on both my Homelite T-12 (factory) and the newer style I installed on my GTHL is about 5 3/4". If you do a complete wrap of the pulley with the HA belt, the length of belt used is 16 1/8", which calculates to a 5.133" effective diameter. The belt rides down in the pulley a bit, the top of the belt is NOT flush with the OD of the pulley. On the GTHL, with the newer style blower with a stock 7" or 6 1/2" driven pulley I used a 66.1" HA belt, part #174224. The hitch used was the 7000 series double idler pulley setup without clutch (not FDT hitch, it has shorter "ears").

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Brettw
Thanks so far. The PO had used a shaft mounted drive pulley and the blower has the required setup for that function. I am working on a way to clutch this setup. Regardless of model or how it is set up, if the shaft at WOT is turning at 3600 rpm, it should be the same diameter pulley as any front pto drive to turn the blower at the proper rpm, should it not?

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PhanDad
Brett, yes the pulley ratio should be kept the same to keep the same blower speed. The Simplicity snowblower (Driven Pulley Diameter)/(Driver Pulley Diameter) design ratio is about 1.17. This is true for both the FDT tractors (5.25"/4.5") and the RBT tractors (7"/6"). Decreasing the blower pulley diameter or increasing the drive pulley diameter will increase the blower speed. There is a fairly recent post about speeding up the blower.

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hotrodtractor
I just bought a front electric pto for my command have not installed yet but went for largest Al Eden could find me think it was 7" more later

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Brettw
Eventually, I will likely end up getting an electric PTO for the Magnum, if available. Sounds like Uncle Al, the Club Members Pal is in store for a call from me. As far as diameter, a 5" pulley with an effective use of say 4-3/4" would amount to a circumference of approximately 14.9", about half of which is used by the belt. A 6" pulley would be about 18" so half again would be used by the belt. This would explain why the Simplicity belt was longer than the belt that is being used in the PO's setup. The pulley difference alone accounts for about an 1-1/2". Combine that with a relatively long throw of adjustment on the idler pulley, and the Simplicity belt would likely work exactly as designed. Now the dilemma. It actually threw snow very well with the (Now Ryan's) K 301 12 horse. Powered now with the 18 it should be unstoppable. So, do you still increase blower speed to the correct WOT RPM, or do you let sleeping dogs lie? Hmmmmm....

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BLT
I have a 1690547 36" blower with the front PTO and I had all I could do to get a 70" belt on. Time will tell. I have one notch left to adjust spring tension if I have to. As far as hitch and idler pulleys go the are correct.

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PhanDad
I'm not sure how the position of front crank diameter step on the Kohler twins compares to the Briggs or Kohler singles. The distance from the step on the crank to the pulley centerline is about 3" for the Briggs. I have drawings of the new style (one piece) electric PTOs from Warner. They are part numbers 5215-142 for the 1" diameter Briggs crank and 5215-140 for the 1 1/8"" diameter Kohler crank. I only have personal experience with the Briggs. Warner gave me info about the Kohler when I talked to them about Simplicity/Homelite electric PTOs several years ago.

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Brettw
OK. So now I'm curious. What is the ratio of the BGB? Is it 1 to 1 as I thought it was? If so, why does the proper front PTO drive pulley seem to be a 6" by what I am reading here, but the center PTO pulley appears to be a 5" or slightly smaller? Wouldn't the drive pulley, regardless of location be the same to drive the blower? If I understand this correctly, a center driven blower would turn slower than a front driven blower, and this does not make sense to me, unless the BGB ratio is not 1 to 1.

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larry8200
The BGB is 1:1, I think you will find the blowers made to run off the center PTO have a smaller pulley than the ones that run off the front PTO.

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PhanDad
I did a belt wrap on the center PTO pulley on my 7117. The belt rides basically flush with the top of the pulley. The wrap is 15", so the effective diameter is 4.75", slightly less than the front electric PTO effective diameter of 5.13". So it appears Brett's statement "a center driven blower would turn slower than a front driven blower" is true, blower speed has been decreasing slightly with time: FDT setup the blower runs at 87% of engine speed. RBT with front PTO the blower runs at 80% of engine speed. RBT with center PTO the blower runs at 74% of engine speed. The above are based on belt wrap lengths, not outside pulley diameters.

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hotrodtractor
got the electric clutch hooked up late last night. Had to pull engine to get it on. Works great and clears hood, frame... Only issue is I went with larger dia so pully hit muffler bottom, a little hammering of the muffler case and fits like a glove. Used a regular 15a switch. will gets some pics up soon. Have not powered anything yet but will use the brush cutter this summer with it. Have thought about running the blower off this (have the double pulley hitch also from my old 7010) but Al's opinion was that I would have less issues just using the bgb pulley as the oem did.

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DanD
I just looked up the parts list on Jack's web site. The driven pulley on a model 1690032 blower made for the front pto drive is listed as 7" OD, Simplicity part #2171248. I then downloaded from Simplicity several copies of the parts list for the 1691522 snowblower made for the large frame tractors to be driven from the center PTO and the driven pulley is still the same part number. This concerns me a little bit since this year I just changed my snowblower from an old Sovereign with the front PTO to a new Sovereign with the center drive. It was obvious to me that the pulley on the front PTO was larger than the pulley on the center PTO, but I assumed the pulley on the BGB probably ran a little faster than engine speed. Now I hear that it's the same. I hope the blower will perform OK on the new tractor. Anyone else ever gome from an old Sovereign to a new for a blower tractor?

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