PTO types clarification??

[Brambleberry]

I'm about to go pick up a 97 Kubota L4850 EC (hydraulic shuttle shift).

One last thing I'm wanting to figure out before making the long trip and purchase is to know more details of the PTO setup that I'm purchasing.

I'm a little confused about terminology, and just want some clarification...

Here's what I think is going on and I want to know whether it's correct or not:

Live PTO is a 2 stage clutch that lets you shift gears without disengaging the PTO by pressing down halfway. Pressing to the floor will open the clutch for both transmission and pto.

Independent (hydraulic?) PTO: PTO engagement is controlled by a switch or a mechanical lever (hyd valve??) That has nothing to do with the transmission clutch. Typically (always??) has a hydraulic brake that stops the PTO immediately upon disengagement. I've heard some issues with this brake getting ruined by too much impact and wear, and that it's best to keep an overrunning coupler on the shaft to let the implement freewheel down to a stop instead of slamming to a stop.

"Non-Live" (no idea what is supposed to be called) PTO is what my Pasquali 988 has and it's incredibly frustrating, I love this tractor but absolutely cannot keep living with a "dead" PTO. This PTO cannot be continuous when shifting gears and the implement winds down, losing momentum every time you clutch to shift or stop. Terribly slow work mowing brush, slopes etc. PTO can be run without tractor moving by engaging PTO with transmission in neutral.

So I'm wondering what type this L4850 hydraulic shuttle shift has, partly out of curiosity and partly so I can check that the PTO brake (if it has one) is not broken (requires splitting the tractor to fix, as I understand it).

Thanks for any help and insight into this, I'm hoping it can also help clarify the terminology for other folks shopping for the ideal tractor.

 

[rScotty]

Yes, the terminology is all over the place.

Most will agree that there are three main classes of PTO from simplest to most complex.

1. transmission driven - this is your "non-live" PTO on the Pasqualli and many other early tractors. It works just as you describe. PTO turns whenever transmission clutch is engaged whether in gear or not. A big problem was that you can't bring the implement up to operating speed with the PTO before the tractor starts moving.
You hardly ever see this PTO anymore except on very basic models and of course vintage tractors maybe pre- 1955.

2. Live PTO - This is like #1, except that it had a two stage foot clutch. A person with a well-educated clutch foot could separate the PTO from the motion of the tractor. Basically you could stop and change gears while the PTO was still turning. It also allowed you to get the PTO implement up to speed before starting off.
It's not a style of PTO much seen today...although that may be because foot clutch & gear transmissions aren't so popular.
You still see this PTO sometimes today, but becoming rare.

3. Today most PTOs are variations on what is called a "Fully Independent PTO". Some are more independent than others. All will have the PTO engaged by a lever or solenoid switch so that the PTO is totally independent of the tractor's forward motion. The very best PTOs will have an additional manual clutch just for the PTO. With that clutch, engagement/disengagement of heavy PTO loads can be regulated to protect the PTO drive system.
This Independent PTO is also the class of PTO where you see other variations like the inertial brake you mentioned.

Regardless of type, ALL PTOs need an over-running clutch.

YMMV, hope this helps.
rScotty

 

[5030]

If it's a hydraulic shuttle, the pto clutch will be a multi plate wet pack and the pto will be a 6 spline 540. With a hydraulic shuttle, the is no dry clutch in the bellhousing at all, just a damper plate. The main clutch is also a wet multi plate pack and all the 'clutch' pedal does is act on the proportioning valve that controls the lock up pressure to the wet pack.

What I have and the only way to fly in my opinion because all dry clutches will fail at some point and all will require a split to replace.

Kubota's especially require an over running clutch on any implement that don't have one because the wet pack clutch brake on a Kubota is notoriously weak and any implement that don't have a built in over running clutch will destroy the internal clutch brake in short order. Once the internal clutch brake is destroyed, the pto stub will constantly free wheel.

Something you need to check when buying a used Kubota with a hydraulic shuttle. Grab the stub and turn it (engine off pto disengaged). If it turns freely, the clutch brake is shot. If it turns about 1/2 turn and stops, the clutch brake is ok. Renewing a clutch brake on a hydraulic shuttle tractor entails splitting the unit as the wet pack is in front of the final drive ring and pinion and is only accessable from the front of the gearcase.

If the pto stub rotates freely, pass on the unit. Not a cheap fix by a long shot. The 'fix' is easy, replacing the brake discs, but the access is costly.

 

[mo1]

Yes, the terminology is all over the place.

Most will agree that there are three main classes of PTO from simplest to most complex.

1. transmission driven - this is your "non-live" PTO on the Pasqualli and many other early tractors. It works just as you describe. PTO turns whenever transmission clutch is engaged whether in gear or not. A big problem was that you can't bring the implement up to operating speed with the PTO before the tractor starts moving.
You hardly ever see this PTO anymore except on very basic models and of course vintage tractors maybe pre- 1955.

2. Live PTO - This is like #1, except that it had a two stage foot clutch. A person with a well-educated clutch foot could separate the PTO from the motion of the tractor. Basically you could stop and change gears while the PTO was still turning. It also allowed you to get the PTO implement up to speed before starting off.
It's not a style of PTO much seen today...although that may be because foot clutch & gear transmissions aren't so popular.
You still see this PTO sometimes today, but becoming rare.

3. Today most PTOs are variations on what is called a "Fully Independent PTO". Some are more independent than others. All will have the PTO engaged by a lever or solenoid switch so that the PTO is totally independent of the tractor's forward motion. The very best PTOs will have an additional manual clutch just for the PTO. With that clutch, engagement/disengagement of heavy PTO loads can be regulated to protect the PTO drive system.
This Independent PTO is also the class of PTO where you see other variations like the inertial brake you mentioned.

Regardless of type, ALL PTOs need an over-running clutch.

YMMV, hope this helps.
rScotty

Kubota doesn't put access to their manuals online for free, so I can't look to see what kind of engagement it has. I looked at their parts list to get an idea and there are apparently three different types of clutch setups for the L4850. All are dry clutches. One had a single plate and the other two were dual-plate. A single clutch plate would suggest a transmission-driven PTO as there was no diagram showing a wet clutch pack or any other mechanism to drive the PTO. The two-plate setups would be either a live or independent setup. The PTO engagement is mechanical via a lever but the diagram didn't show where this attached to, so no idea if this is independent or live. Kubota still makes both types today, so anybody's guess without a manual or sitting on the tractor.

Essentially all tractors made in the last several decades will have overrunning clutches in the tractor PTO setup. You have to go a long ways back to not have this. However, this will only prevent the implement from overrunning the transmission when the PTO is engaged. An overrunning PTO clutch is smart on a high inertia implement on a PTO with a PTO brake as the clutch will let the PTO brake stop only the PTO shaft and let the implement overrun the brake and coast to a stop rather than roast the PTO brake trying to stop the implement. It will also let you turn the PTO shaft to line up the splines on an implement rather than turn the implement's PTO driveline. (Try turning the driveline on a multiple gearbox bush hog or baler and getting it to line up, it's fiddly and not fun.) Often electrohydraulically-operated independent PTOs have a brake but not always, and often mechanically-operated PTOs do not have a brake. Electrohydraulic PTO clutches often abruptly engage as well, while you can feather a mechanical one. I much prefer the brake-less mechanical independent clutches myself, which is why my tractor has one. Unfortunately they are much less common today than they used to be. You essentially only see them on basic 50-75 HP utility tractors as anything with a wet clutch hydraulic reverser transmission or a hydrostatic unit will have an electrohydraulic PTO clutch.

 

[Sawyer Rob]

Yes, the terminology is all over the place.

Most will agree that there are three main classes of PTO from simplest to most complex.

1. transmission driven - this is your "non-live" PTO on the Pasqualli and many other early tractors. It works just as you describe. PTO turns whenever transmission clutch is engaged whether in gear or not. A big problem was that you can't bring the implement up to operating speed with the PTO before the tractor starts moving.
You hardly ever see this PTO anymore except on very basic models and of course vintage tractors maybe pre- 1955.

2. Live PTO - This is like #1, except that it had a two stage foot clutch. A person with a well-educated clutch foot could separate the PTO from the motion of the tractor. Basically you could stop and change gears while the PTO was still turning. It also allowed you to get the PTO implement up to speed before starting off.
It's not a style of PTO much seen today...although that may be because foot clutch & gear transmissions aren't so popular.
You still see this PTO sometimes today, but becoming rare.

3. Today most PTOs are variations on what is called a "Fully Independent PTO". Some are more independent than others. All will have the PTO engaged by a lever or solenoid switch so that the PTO is totally independent of the tractor's forward motion. The very best PTOs will have an additional manual clutch just for the PTO. With that clutch, engagement/disengagement of heavy PTO loads can be regulated to protect the PTO drive system.
This Independent PTO is also the class of PTO where you see other variations like the inertial brake you mentioned.

Regardless of type, ALL PTOs need an over-running clutch.

YMMV, hope this helps.
rScotty

Hey, you forgot to explain how an Allis Chalmers WD has a "transmission" driven PTO, but it's still live.

SR

 

[JC-jetro]

Just to add to what everyone said. My Ford 1700 does have , transmission driven PTO on Not Live with an internal overrunning clutch. The PTO can only run if tractor is in motion or if the PTO lever is engaged, gear in neutral, clutch pedal depressed and tractor turned on and once I let the clutch engage than PTO is running. It is a bit of pain but doable. With the PTO running I slowly back in to a vegetation, clutch and put the gear in neutral in low rpm and then let go of the clutch and PTO starts turning and picking up speed while tractor is stationary. To move forward then I lower the rpm , put the tractor in gear while stationary,let go of clutch and start moving with the PTO turning. It is pain but doable. Just to add I do not not have Synchromesh transmission and have to come to full stop to change gear.

on my kubota I have a fully independent PTO. I have a single stage dry disk for the transmission. With independent or live PTO , you will have two input shafts, one hollow and on solid inside of the hollow. In the flavor my my kubota MX series,The inner shaft is directly coupled and splined to flywheel. Anytime the engine is on the PTO input shaft turns . The input shaft then has a set of wet clutch disk that will be activated by hydraulic pressure to transfer the torque to final PTO shaft. I have not seen an overrunning internal clutch in the parts break down. There is another flavor of the independent PTO that on a single clutch friction disk is coupled to the inside solid PTO shaft that connects to flywheel with a pilot bearing. The PTO outer shaft is splined to the pressure plate splines and anytime the tractor is running the flywheel is turning whether tractor is stationary or in motion and in turn PTO input shaft . This PTO input shaft then is coupled to final PTO shaft in the diffy area mechanically or hydraulically.

Now my question to the group. I have a 5 foot , tiller and brush hog that is a perfect match with my Ford. I yet to use my Kubota PTO as I mainly use it for loader work and moving stuff. What is the consensus of the group on using an external overrunning clutch with the independent PTO with set of wet clutch? That is for future if I decided to get a larger brush hog. Obviously any rotating equipment and tractor is and will be protected by a shear pin or slip clutch.

 

[ericm979]

On an independent PTO with brake you should throttle down to idle while the PTO is engaged to let the engine slow the implement before turning the PTO off. That reduces wear on the PTO brake. And throttle down to idle before turning it on as well, to reduce wear on the PTO clutch. For my tractor both of those work well even with a chipper that has a 200lb flywheel that's geared up 2:1. When I chop the throttle the engine slows down about as quickly as it does with no load, and it has no problem starting the chipper turning at idle. I think that by following these procedures the wear on the brake and clutch will be low.

There might be a time where you want to stop the implement ASAP, so the PTO brake is a good idea. The overrunning clutch will eliminate the brake, eliminating that safety feature. I think I have wanted that once in the last four years so it's not a common thing, but I'm also pretty safety concious and rarely need any of the safety features in my equipment (i.e. saw chaps and chain brake). They're there in case I make a mistake, not for everyday use.

 

[JC-jetro]

On an independent PTO with brake you should throttle down to idle while the PTO is engaged to let the engine slow the implement before turning the PTO off. That reduces wear on the PTO brake. And throttle down to idle before turning it on as well, to reduce wear on the PTO clutch.

Yup, that's exactly how I do it and try to never be in a hurry with my tractor. On top of that I always use the lightest shear pin I can buy from TSC by the lbs. Much easier to change a busted shear pin than the alternative. Overall, wet clutches for engagement beats dry clutch in longevity and performance but anything can be abused.

 

[Texasmark]

Yes, the terminology is all over the place.

Most will agree that there are three main classes of PTO from simplest to most complex.

1. transmission driven - this is your "non-live" PTO on the Pasqualli and many other early tractors. It works just as you describe. PTO turns whenever transmission clutch is engaged whether in gear or not. A big problem was that you can't bring the implement up to operating speed with the PTO before the tractor starts moving.
You hardly ever see this PTO anymore except on very basic models and of course vintage tractors maybe pre- 1955.

2. Live PTO - This is like #1, except that it had a two stage foot clutch. A person with a well-educated clutch foot could separate the PTO from the motion of the tractor. Basically you could stop and change gears while the PTO was still turning. It also allowed you to get the PTO implement up to speed before starting off.
It's not a style of PTO much seen today...although that may be because foot clutch & gear transmissions aren't so popular.
You still see this PTO sometimes today, but becoming rare.

3. Today most PTOs are variations on what is called a "Fully Independent PTO". Some are more independent than others. All will have the PTO engaged by a lever or solenoid switch so that the PTO is totally independent of the tractor's forward motion. The very best PTOs will have an additional manual clutch just for the PTO. With that clutch, engagement/disengagement of heavy PTO loads can be regulated to protect the PTO drive system.
This Independent PTO is also the class of PTO where you see other variations like the inertial brake you mentioned.

Regardless of type, ALL PTOs need an over-running clutch.

YMMV, hope this helps.
rScotty

My Branson 2007 6530 has the shuttle shift tranny. The 3 speed selectable PTO is Independent but has a "Live" position on the switch. As mentioned above, in this PTO position, pushing in the clutch will disengage the PTO. Difference in this "Live" and the ones on my vintage Ford tractors is that there is a 2 stage clutch performing the operation on them....the other stage drives the tractor, foot operated. This one is merely a switch that is activated by the clutch pedal and disengages the electrically activated, Independent PTO.

 

[Hay Dude]

I’ll never forget making a big mistake of turning on a PTO while hooked to a spreader one cold morning. The material in the spreader froze, despite no freeze warnings on my weather forecast. I didn’t realize it was frozen and burned up my pto clutch packs.

warped & burnt