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KenSc
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2002-02-23          35825

I have an tentative agreement to buy a John Deere 950. I plan to use it for snow removal and lawn mowing with a 3pt finish mower. I went to check all the fine details of the tractor today and was shocked to find out it doesn't have a live pto! The dealer told me that only a 1050 and up have a live pto. Is this for real? Is there any compact tractor that has a live PTO? The dealer also has a small FORD compact with a loader and he says it also does not have a live PTO. I see a lot of discussion on this board about the use of 3pt mowers and find it hard to believe that nobody has a live PTO. I have read about 2-stage clutches. Is that an option on compact tractors? The dealer wasn't really checked out on the compacts and wasn't aware of a differential lock that I read about on this board so just maybe there is somethng he missed about the missing live PTO. Otherwise the 950 seems to be ideal.

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Mrwurm
Join Date: Feb 2002
Posts: 184 South East Michigan
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2002-02-23          35826

ken, I have the original product brochure for the 50 series tractors in front of me as I type. The book lists the 650 and 750 as having a transmission-driven pto with single stage clutch. 850, 950, 1050, 1250, have continuos-running pto with dual-stage clutch. 1450, 1650 have independent pto. I can't gaurantee what your tractor has, but that is what is in my product brochure. Brochure also states that 850/950 have " continuous pto for stop-and-go operation without disengaging the pto"
Jerry
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Todd Wilson
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2002-02-23          35830

Its my understanding the first few years the 950 was made they didnt have the 2 stage clutch. I have a 1982 JD 950 and it doesnt have it. You push the clutch in and the PTO stops being driven by the engine. If you want to run a PTO Generator or something like that you put the gear selector in 2nd and the HI/LOW range in nuetral and engage the PTO and run. The gear being in 2nd allows for PTO lubrication.
My 950 is sometimes a pain if you want to back up the bushhog into a tight spot the blades will slow down as you stop and shift to reverse and then speed up as you back up. Sometimes the blades are not up to speed and it doesnt cut as well as it should. Once you get a feel for how it all works you can get it to cut.

Todd

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TomG
Join Date: Feb 2002
Posts: 5406 Upper Ottawa Valley
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2002-02-24          35837

My Ford 1710 has the optional synchromesh 12 x 4 TX. The optional TX provides live PTO by a 2-stage clutch. The standard non-synchromesh TX uses a TX driven PTO and has a built in over-running clutch. I guess there's a chance that live PTO came with optional transmissions on some JD's.

People certainly were able to use PTO implements OK before the days of live PTO's--before the days of over running clutches and live hydraulics for that matter. It can be done. It's just not very convenient. I guess that the slowing of a mower when clutching a tractor could be minimized by shifting to neutral with the clutch out to bring the blades back up to speed before shifting to reverse. Doing that doesn't sound like a great joy though.

I don't have a mower, but my aggravation would be my snow blower. Without live PTO, the chute would clog even in moderately wet snows most times the tractor is clutched.
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Todd Wilson
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2002-02-24          35849

I just looked in my tech manual for my 950. If the serial # is greater then 20001 it has the 2 stage clutch. This would make life a little easier when running a mower via PTO.


Todd

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TomG
Join Date: Feb 2002
Posts: 5406 Upper Ottawa Valley
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2002-02-25          35852

Todd: I've been thinking about your comment of having to put the TX in 2nd and the range in neutral to lubricate the PTO. I have a curiosity about how things work and I’ve been wondering about this one.

I believe TX driven PTO’s take their inputs off the TX input or counter shaft. There may be inadequate oil sling to lubricate the PTO drive gears unless the gears on the output shaft also are rotating. For a non-synchromesh TX, that would mean that the TX has to be in gear and the range in neutral. It shouldn't make any difference with a synchromesh TX since the gears are in constant mesh. However, I’ve never thought about how high the normal oil level in the sump is. I’ve always assumed that the gears are partially in the oil bath. The idea of oil sling would be nonsensical if the gears are completely submerged.

The notion of why second gear specifically is a bit of a mystery, and I don't know if the TX is synchromesh. Guess I might learn something here.
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Todd Wilson
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2002-02-25          35869

You have to stop my 950 to change gears. Would that be a collar shift? I figured the 2nd gear deal was to sling oil myself. I'll look in my tech manual and see if I can find a schematic of the internals of that area.


Todd
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TomG
Join Date: Feb 2002
Posts: 5406 Upper Ottawa Valley
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2002-02-26          35880

Todd: 'Collar shift' could be the term, but I've always just called them sliding gears. The shift forks slide gears along splined shafts, and the gears have to find their own meshes. If you're supposed to stop before shifting, then the TX isn't synchromesh. I say supposed to stop, because old time transport trucks didn't have synchromesh. They were shifted by double clutching, which is a technique that might be adapted for tractor use when the foot throttle rather than hand throttle is used.

I noticed in my Ford 1710 manual that the schematic for the non-synchromesh TX that the PTO drive gear is on the end of the front counter shaft and followed by 1st gear and then second. The diameter of the PTO and 2nd gears are similar while 1st is smaller. If the TX gears are partially in an oil bath, then the PTO gear is as well. Since 2nd gear is located a greater distance from the PTO gear than 1st, there is a possibility that oil sling from 2nd is needed for the PTO shaft rather than the PTO gear. All speculation on my part of course, and your TX may not be constructed the same.
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Todd Wilson
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2002-02-26          35888

I looked at my JD 950 tech manual and could not find anything specific to oiling so I would assume it must get it from the gears slinging oil about. The more I think about it the more I wonder if running in 1st low while rototilling or going extra slow while mowing is actually bad or not as good for the insides as you are running the PTO and you arent in 2nd gear.


Todd
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Murf
Join Date: Dec 1999
Posts: 7249 Toronto Area, Ontario, Canada
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2002-02-26          35889

It's likely more to do with the physical layout of the different gears in the transmission case. Second gear probably hangs the lowest of all of them, therefore would sling oil the best, or else it is in line with the PTO gear (or very close to it) and therefore slings the oil directly onto it. As for lubrication while working, I wouldn't fret over it, the simple motion of the tractor as it moves will cause enough sloshing around of the oil for it to come into contact with the gears and cause adequate slinging action. Best of luck. ....

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TomG
Join Date: Feb 2002
Posts: 5406 Upper Ottawa Valley
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2002-02-27          35902

Interesting side-discussion, and I'm always ready for an excuse to dive into my repair manual. As with Murf, I think the 2nd gear idea just helps lubrication a bit while the tractor is stationary. I wonder how many owners follow the manual?

Of course, I got my typical reaction of brain fogging when I referred to my manual. Seems like my eyes go around in circles every time I look at a TX diagram and it affects my thinking. I still remember doing a minor rebuild on my old Econoline TX (a 3-speed synchromesh). Before putting the cover back on, I turned the input shaft by hand and operated the shift levers. 'CLICK' goes something, and I could see the main (output) shaft speed change. I put the TX back on the van thinking: 'Well, I've had it apart and touched everything with my own hands. I can see that it shifts, but danged if I can figure exactly what happens.' I suppose I could have concocted an intellectual explanation involving blocking and synchronizing rings and locking dogs etc., but in my heat I knew it was magic. Every time I look in a manual, it's still magic. Doesn't mean that I couldn't fix one though.
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Mrwurm
Join Date: Feb 2002
Posts: 184 South East Michigan
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2002-02-27          35904

My owners manual for my 650 also recommends that stationary pto operations be done in neutral range with gearshift in 2nd gear. My manual does not say anything about this action lubricating the pto. But, it does say to do this to "prevent transmission damage." ....

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Peters
Join Date: Feb 2002
Posts: 3034 Northern AL
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2002-02-27          35916

Tractors in general do not have syncro transmissions. In the shuttle shift equipment I have seen the syncro is just between the forward and reverse cogs. You still need to stop before you switch gears. The only tractor that I have seen literature on that may have a syncro for the gears is Kioti, most others use the hydro.
The old truck and car transmission, non syncro, I believe were of a different construction than a tractors. Shifting into neutral and clutching brought the gears to speed so that they could mesh. I think you could double clutch all day with a tractor and only get the gears to mess if you were lucky. Roll the dice, I am not sure what the odds are.
I can not say what the differences are in the transmissions design is exactly, for the older non syncro and tractor. I have only rebuilt syncro, tractors and marine. With the emphasis on marine. ....

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Roger L.
Join Date: Jun 1999
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2002-02-27          35930

Some of the shuttle shifts have internal clutch packs right where you would expect the syncros to be. Instead of shifting the cogs, the shuttle lever actuates one or the other of the internal clutches. Larger tractors use that system and call it "power shift".
I've experienced Tom's mental fog when looking at transmissions myself. A trick that helps me is to remember that whenever you have two gears on one shaft driving two gears on another shaft then one of those shafts is not solid clear through. The two piece shaft is typically joined by a bearing somewhere in its length between its two gears so that each end can rotate at a different speed.
In designing transmissions a lot of attention is paid to "spin down rate". That determines how long a shaft and gear will go on spinning when it is no longer driven, and has a large effect of how the tranny shifts. ....

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TomG
Join Date: Feb 2002
Posts: 5406 Upper Ottawa Valley
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2002-02-28          35939

Yes it's entirely possible that truck and tractor TX's are different and double clutching wouldn't work on tractors. I seem to recall a discussion about power shift being too slow. It's possible that tractor TX's have the long spin down rates Roger mentioned and that adds to synchronization problems even with power shift.

Rather than recommend that somebody else try double clutching, I guess I could give it a test with my ranges. On my Ford 1710, an optional 12 x 4 synchro TX with live PTO was offered, which is the one I'm fortunate to have. Three forward speeds plus reverse are synchro but the four ranges aren't.

Did I say 'In my heat?' that must have been just after I busted my knuckles. I meant 'In my heart.' Dang spell checker dependence again. Well, it was just my brain fog. Must have still been thinking about transmission diagrams. Yesterday I got a new cause of brain fog. My long awaited NH parts manual was delivered. Now I have a whole bunch of diagrams that are much more detailed than the repair manual drawings.
....

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