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OT, (a little) Ground-Driven PTO |
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Gatz in NE
Orange Level Joined: 11 Sep 2009 Location: Lincoln, NE Points: 1037 |
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Posted: 28 Nov 2009 at 9:11am |
May be a dumb question... Some Allis, Ford & MF tractors (others, I'm sure) have a Ground-Driven PTO option or selection.
What was this used for? Raking? Tedding?
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Gerald J.
Orange Level Joined: 12 Sep 2009 Location: Hamilton Co, IA Points: 5636 |
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Those are the most logical uses. I suppose it could be use to drive a three point planter or drill too. My MF-135 manual says, "This feature is very desireable when operating implements which require operating speed proportional to the tractor forward speed, i.e., PTO driven Side Delivery Rake, Lister Planter, etc." It goes on to note that it better be shifted out of gear when backing the tractor in case the implement won't survive reversing the PTO shaft. But that also hints it might be a handy way to reverse the PTO to cough out a clog in some processing implement.
I have seen such a PTO driven MF rake but not anything else that I noticed. I used a PTO driven planter a few years, but it was driving a fan and needed constant engine drive, not ground speed proportional. Gerald J. |
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CTuckerNWIL
Orange Level Joined: 11 Sep 2009 Location: NW Illinois Points: 22823 |
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That might be what is needed for the Dearborn rake my great uncle had. I used it once on the 8N and ran in third at an idle and it still beat all the leaves off the hay and twisted it into a rope.
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http://www.ae-ta.com
Lena 1935 WC12xxx, Willie 1951 CA6xx Dad bought new, 1954WD45 PS, 1960 D17 NF |
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FRANKO
Bronze Level Joined: 13 Sep 2009 Points: 26 |
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I think "ground driven" is a term left over from the animal power days because horses or oxen did not have a rotating shaft sticking out the back end! Any power needed to rotate something such as a side delivery rake needed to be taken from a wheel touching the ground. For tractors the PTO speed is proportional to engine speed, and ground speed is proportioal to engine speed, therefore PTO speed is always proportional to ground speed. You can change the proportionality constant by changing transmission gear ratios. If the PTO shaft is driven from a connection on the output side of the transmission, then only one ratio is available and it would allow the PTO to turn backwards when the tractor reversed. That must be the new definition of ground driven!
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TomSEOH
Silver Level Joined: 13 Sep 2009 Location: SE Ohio Points: 170 |
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Ground driven PTO is exactly what is says it is, PTO is directly proportionate to wheel speed and yes, if the tractor is placed in reverse it will turn the PTO in the opposite direction. I have owned several tractors with the option and about all i ever used it for was to unplug a haybine or an old type (closed throat round baler) Tom
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Dusty MI
Orange Level Joined: 13 Sep 2009 Location: Charlotte, Mi Points: 5058 |
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What different make of tractors was that available?
Dusty
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917 H, '48 G, '65 D-10 series III "Allis Express"
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CTuckerNWIL
Orange Level Joined: 11 Sep 2009 Location: NW Illinois Points: 22823 |
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My BIL has a Massey with it. I don't remember the model number but it is probably like late 60's or early 70's built.
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http://www.ae-ta.com
Lena 1935 WC12xxx, Willie 1951 CA6xx Dad bought new, 1954WD45 PS, 1960 D17 NF |
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StanInLowerAL
Orange Level Joined: 13 Sep 2009 Location: South Alabama Points: 222 |
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I have a MF 135 with this feature.
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Gerald J.
Orange Level Joined: 12 Sep 2009 Location: Hamilton Co, IA Points: 5636 |
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But Franko, in a modern tractor with say a dozen speeds forward (like my 1968 MF-135) there are that dozen ratios from ground speed to PTO and the standard PTO speed is defined to be 540 in this case with the engine at 1850 RPM which is indicated on the tachometer as PTO speed. The MF-135 regular PTO is not driven by the transmission, but has its own clutch, shafts, and gears totally independent of the transmission but often concentric with transmission parts like the input shaft and the cluster shaft. That's true whether the two stage clutch on the clutch pedal for "live" PTO or with its own hydraulic clutch for "independent" PTO.
The ground speed gear position is driven by a gear on the differential pinion shaft and is defined to turn approximately one revolution per 20" of forward motion. That will be affected by the choice of rear tires, whether 14.9x24 or 12.4x28. I had a couple city boys on the hay rack one day and they shouted to slow down because I was putting bales on the rack faster than they could stack (comfortably). So I held the engine speed constant and shifted down a gear. They still weren't happy so I shifted down another and another. When I was down to 1.5 mph at PTO speed and they were still grumbling, I paused and had a little chat pointing out that the baler needed PTO speed but that I had cut ground speed by a factor of 3 so surely they weren't being overloaded by bales. They hadn't checked ground speed and bale frequency, they just listened to engine speed. We baled successfully that time and several more without doing them harm. I paid them a buck over minimum wage too. Gerald J. |
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Gatz in NE
Orange Level Joined: 11 Sep 2009 Location: Lincoln, NE Points: 1037 |
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I don't quite understand the 1st & 2nd sentences... esp. "If the PTO shaft is driven from a connection on the output side of the transmission..."
Does this imply there is some other connection for Ground-Driven PTO that is NOT on the output side (bevel pinion gear shaft) and thus would be proportional to the transmission gear selected......or ?
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Dusty MI
Orange Level Joined: 13 Sep 2009 Location: Charlotte, Mi Points: 5058 |
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As we al know the standard PTO speed is 535 RPM. Some MF models added a second gear for the PTO. Which is related to the ground speed. If you change the ground speed by shifting the transmission gear then the speed of the PTO changes.
I think MF is the only manufacture that had this. That's why I asked in the earlier post.
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917 H, '48 G, '65 D-10 series III "Allis Express"
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Gerald J.
Orange Level Joined: 12 Sep 2009 Location: Hamilton Co, IA Points: 5636 |
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Gatz, some PTO were driven directly off the second shaft of the transmission. Ford N series for example. That second shaft always turns at a fixed ratio from engine speed, but ground speed depends on which gear is connected to the differential. So that in Frankos mind allows different ground ratios depending on the drive gear. But at what sensitivity. Say at PTO speed in 1st gear (like an 8N) at 2 mph, that is about 10,500 feet per hour, 32,400 revolutions of the PTO shaft (540 x 60) so that is about 3 revolutions per foot of travel. In road gear at 12 mph, it would be about a revolution per foot of travel, not far from the MF-135 standard.
Gerald J. |
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Dave King
Silver Level Joined: 24 Sep 2009 Location: OK Points: 97 |
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My uncle's AA8610 has an "economy" setting that seems to be ground driven in some fashion, but I have never seen it used to know what sort of speed differences could be attained.
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DreaminGA
Silver Level Joined: 20 Oct 2009 Location: Elberton, GA Points: 84 |
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Just to mix things up a bit, Kubota and other import tractors do have PTOs that are affected by transmission gear selection. I'm not sure about the newer ones, but the older Kubotas and Yanmars seem to have this. Some of those have multiple speed selectable PTOs to help match PTO speed with ground speed. Really affects performance and horsepower with flail mowers and other high load implements. Dream.
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It wasn't me! It was a short, fat, tall, skinny guy that looked like me!
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Gatz in NE
Orange Level Joined: 11 Sep 2009 Location: Lincoln, NE Points: 1037 |
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thanks for all the answers...it makes a lot more sense now. All this discussion just reminded me of an incident many years ago when I was a young kid combining oats for a neighbor with his WD45 and 60.
He had told me to use the hand clutch if there was a need to stop, and of course I knew this as we had a D17.
Musta got real nervous when coming through a ditch and pushed in the foot clutch to slow down....totally forgot the hand clutch.
Man, I caught hell for doing that....although to this day, I don't know why he got so PO'd
This was my introduction to "ground-driven PTO" lol
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