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Transmission versus Live PTO

E

EmeradKondo

New User
Would someone explain to me the difference between a transmission drive PTO and a live PTO. Does the PTO stop when the tractor stops in a transmission drive. And keeps running in a Live PTO setup?

If that is true, what RPM does the PTO run in a transmission drive setup? I'm guessing from zero up to 540 RPM - something must govern the top RPM.

Thanks,
Rich
Maple Valley, WA
1948 Farmall Cub
1967 Ford 3000
2008 Kubota BX24
 

540 or 1000 is the rated speed of the PTO. It will turn faster than that if the engine speed is above the RPM to obtain that rated speed. It will turn slower if the engine RPM is lower than the PTO rated speed. PTO speed is all governed by the placement of the throttle by the operator.

There are actually three different types of PTO; transmission, live and independent.

You have guessed properly on the transmission PTO. It stops when the transmission does or when the tractor stops moving. All Ford tractors used this type PTO until 1955. Thereafter an example would be an 840 or 850.

The live PTO uses a 2 stage clutch. If the clutch pedal is pushed part way down, it disengages the transmission while the PTO remains engaged. Pushed on down to the running board, both are disengaged. An early example of this system would be an 860 Ford.

Independent PTO utilizes its own separate hydraulic clutch pack and can be engaged/disengaged without using the machine clutch pedal. Ford's early one was contained in the Select-O-Speed transmission. And example would be an 871 or 881,
 
Larry gave an excellent explanation. I just want to add a safety note. With transmission driven PTO in Ford tractors, the PTO is directly coupled to the transmission so if there is a heavy implement that has a lot of rotational momentum, when you push in the clutch the transmission is disengaged from the engine, but the large rotational momentum of the implement is still connected to the transmission and can continue to drive the transmission and rear wheels forward and can overpower the brakes. That is why it is recommended to have an external Over Running Clutch (ORC) on the PTO shaft on the back of the tractor when running a heavy implement with a trans driven PTO. An ORC acts like a ratchet so that the tractor PTO shaft can provide power to turn the implement but when you push in the clutch and apply the brakes the implements rotational momentum will not be transferred back into the transmission.
 
If it helps to visualize...
Photo shows the dual transmission inputs on a 3000.
The inner splined shaft drives the tractor. Outer splined tube drives the pto.
There are two clutch discs on a live pto model. Front one drives the shaft. Rear one drives the tube.
A non-live or transmission pto tractor only has one input shaft which drives both the tractor and pto.
Though both clutches are operated with one pedal, when starting up, the pto engages first and gets your mower up to speed. Then as you continue to let up on the pedal the tractor begins to move. Live also pto lets you push your pedal halfway down to stop the tractor and keep the mower turning. Say if you are bush hogging and the engine starts to lug down in some real thick stuff you can stop the tractor and let the mower catch up.

cvphoto10223.jpg
 
This question was bugging me a while ago also...I got the basic idea but I still don't really know what our backhoe has.

You have to push the clutch pedal in to turn the PTO on that has the hoe pump bolted to it. While sitting in neutral with the tractor running, to use the backhoe. If you drive off, and dont turn the PTO off the hoe pump will keep on running until you push the clutch in, and turn the PTO off.

The clutch pedal has a short travel, not a long one like the manual shows for a 2 stage clutch.... so I'm assuming its a single clutch but what the PTO is, live independent or trans driven... I have no idea.

On this tractor, the only thing the PTO drives is the PTO shaft pump.

Good thread... I might learn something.

(as you can tell... never owned a tractor before this one, don't really know much about them)
 
I played around with the tractor a bit today and learned the PTO turns at a steady 540 rpm, so even though it is driven directly from the transmission, its speed is governed somehow. There is a lever to turn the PTO on and off. If it is on, the clutch will allow the PTO to coast to a stop (not immediate). My interest at the moment is for a brush hog and possibly a tiller, so I can't imagine a scenario in which I would be disappointed in not having a LIVE PTO. I like the fact that if I am brush hogging, the PTO stops when I stop the tractor. I did not know about the PTO Overrun Clutch, but I think I will get one (not very expensive).

Rich
Maple Valley, WA
 
I played around with the tractor a bit today and learned the PTO turns at a steady 540 rpm, so even though it is driven directly from the transmission, its speed is governed somehow.
Click to expand...

Transmission driven PTO is driven off of a counter shaft that is driven off of the main input shaft of the transmission, so the speed of the PTO is determined by the engine rpm's and is not affected by what gear the transmission is in. It even spins in the proper direction when the transmission is in reverse.
 
If you have live pto I recommend you don't use an ORC. My first 3 cylinder Ford was a plain Jane 2000 with non-live pto. I had to use an orc to run a brush mower. Orc meant I had to cut my mower drive line shorter. So I did. I cut the one on my finish mower too just to keep both mowers the same. When I got a 3000 with live pto and didn't need an orc both of my drive shafts were too short. Had to keep using the orc just to hook up. Grrr!
Post the serial and model numbers that are stamped onto your bell housing. We'll tell you if you have live or non-live pto.
PS.
The pto speed is governed by your engine speed. 540 rpms is not an exact number.
At 800 rpms your pto may only be turning 200 rpms. At 1400 maybe 460.
I think 540 pto speed on a 3000 is about 1850 engine rpms. Varies with what transmission you have. Won't hurt to run your mower at 490 rpms or 590 rpms. The magical 540 is just a guideline.
 
(quoted from post at 22:40:09 03/31/20) I played around with the tractor a bit today and learned the PTO turns at a steady 540 rpm, so even though it is driven directly from the transmission, its speed is governed somehow.

Rich
Maple Valley, WA
Click to expand...

Sorry! I think you need to retake that test. You get an F on that learning. As others have said, PTO speed is governed by engine RPMs and does not maintain a magical 540 RPM no matter what everything else is doing..
 
Larry - I plead mea culpa 🤓. Thank you for the education. So a 540/1000 PTO has 2-speed gearing?
That?s more a rhetorical question. Since retiring I?ve learned a lot about tractors, but obviously have a
long way to go. My old HOA neighbors don?t know what they are missing.

Rich
Maple Valley, WA
 
(quoted from post at 11:42:28 04/01/20) Larry - I plead mea culpa . Thank you for the education. So a 540/1000 PTO has 2-speed gearing?
That?s more a rhetorical question. Since retiring I?ve learned a lot about tractors, but obviously have a
long way to go. My old HOA neighbors don?t know what they are missing.

Rich
Maple Valley, WA
Click to expand...
They are two different pto standards. The 1000rpm pto is a bigger pto shaft with different splines. Your 3000 only has 540. 1000 is what you would see on a bigger tractor. The tractor could have two different pto s out the back so it could run either.
 
(quoted from post at 13:08:57 04/01/20)
(quoted from post at 11:42:28 04/01/20) Larry - I plead mea culpa . Thank you for the education. So a 540/1000 PTO has 2-speed gearing?
That?s more a rhetorical question. Since retiring I?ve learned a lot about tractors, but obviously have a
long way to go. My old HOA neighbors don?t know what they are missing.

Rich
Maple Valley, WA
Click to expand...
They are two different pto standards. The 1000rpm pto is a bigger pto shaft with different splines. Your 3000 only has 540. 1000 is what you would see on a bigger tractor. The tractor could have two different pto s out the back so it could run either.
Click to expand...
ight as well throw another one into the mix, the Ground Speed PTO. Speed proportional to ground speed, regardless of transmissionn gear or of engine speed. Pto shaft even reverses direction of rotation if tractor is traveling backwards. I have this on one of my tractors, but don't know of any Ford tractors with Ground Speed PTO, although I can't say whether such might be out there somewhere?
 
(quoted from post at 12:08:57 04/01/20)
(quoted from post at 11:42:28 04/01/20) They are two different pto standards. The 1000rpm pto is a bigger pto shaft with different splines. Your 3000 only has 540. 1000 is what you would see on a bigger tractor. The tractor could have two different pto s out the back so it could run either.
Click to expand...

I don't think you aced it either! There actually 2 different size 1000 speed shafts.

The standard 540 (after about '56 or so on a Ford) is 1 3/8 inch. The small or more common 1000 is also 1 3/8 inch. Granted, the splines are different (6 versus 21), but the two shafts are the same diameter.

The large 1000 is 1 3/4 inch and is splined similar to the small 1000. I don't recall the number of splines off the top of my head on the large 1000.
Click to expand...
 
(quoted from post at 13:12:10 04/01/20) I have this on one of my tractors, but don't know of any Ford tractors with Ground Speed PTO, although I can't say whether such might be out there somewhere?
Click to expand...

Ultra is correct! in *01 series all the *81s were 540/1000/ground speed PTO equipped. The early*000 series also had that option available in the deluxe SOS transmission.
 
(quoted from post at 20:35:53 04/01/20)
(quoted from post at 13:12:10 04/01/20) I have this on one of my tractors, but don't know of any Ford tractors with Ground Speed PTO, although I can't say whether such might be out there somewhere?
Click to expand...

Ultra is correct! in *01 series all the *81s were 540/1000/ground speed PTO equipped. The early*000 series also had that option available in the deluxe SOS transmission.
Click to expand...
ood for all to know & good for the archives!
 
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