The Meaning Of Live

[Harv]

Thought I'd move the discussion of "live" PTO to it's own thread, especially since "Shopping Advice" is no longer appropriate to this poster. /w3tcompact/icons/laugh.gif

When I first started looking into the L2500, owners of the same model claimed that it's PTO was non-live, yet when I asked the dealer, he said it absolutely had live PTO. That sure cleared it up for me. /w3tcompact/icons/tongue.gif

When I saw the dealer in person, I mentioned this to him, and he said, yes, there is a lot of symantic confusion about PTO's. He gave me a detailed and credible explanation of all the variations but unfortunately my head was already swimming with all the input from all the other aspects of the tractor, so I didn't retain all that he said. (That's cop-out talk for "I'm getting old and can't remember so good.")

Anyway, I do remember he started with the history of tractors and PTO's and broke it into several classifications:

1. Non-Live (nobody likes calling this one "dead")
2. Live
3. Live-continuous
4. Live-independent

Non-live is a term that was never used until live PTO's came along.

His definition of "live" had to do with the transmission itself and how power made its way to the PTO. (This was the key part -- sorry I can't dredge up the details). According to him, your basic "live" PTO coasts to a stop when you push in the clutch.

Live-continuous is pretty descriptive -- the PTO keeps going whether you engage the main clutch or not.

Live-independent has a whole separate transmission which can be engaged or disengaged "independent" of the main clutch.

The L2500 is supposed to be last year's L2600, so I consulted the L2600 brochure I picked up a while ago. It avoids the whole issue by listing the PTO as "transmission driven with overrunning clutch".

The owner's manual which I (ahem) have in my hands right now, avoids market-speak altogether and just tells you what happens when you step on the clutch.

Has anybody seen an authoritative definition of all these types? I suppose it doesn't really matter once you've got your tractor and you're used to how it works, but if you're shopping for your next one, it would sure make things simpler if everybody was speaking the same language.

 

[WVBill]

Harv:
I'm sure you'll get a lot of good descriptions here but I found a pretty cogent discussion of PTOs at tractorsmart.com under "technical info".

Bill

 

[DVerbarg]

Harv,

The typically accepted definition of a "live" PTO (at least in this area of the country) is a PTO that will not stop when the clutch is used to disengage the power from the wheels. If you have an "transmission driven with overrunning clutch" my locals would not consider it a live PTO but the overrunning PTO clutch works great for rotary mowing (have one on my old 9N). Without an overrunning clutch the PTO is directly linked to the same gearing that applies power to the wheels.

Without the overrunning clutch you would be faced with the following scenario: picture yourself using the rotary mower (nice picture, huh!) which has quite a bit of momentum in the heavy spinning blades. You approach a fence and press in the clutch to stop. Without the overrunning clutch the momentum of the mower blades will continue to drive the tractor forward until the blades stop, thus propelling yourself through the fence (ouch!). This was the situation that I found myself in with my old 9N until I added the overrunning clutch.

The overrunning clutch can be pictured like a ratchet for a socket set. Power is only able to be applied in one direction. The socket can be turned manually in the same direction without having to move the ratchet. Is this clear as mud, or what? Try it with a ratchet and socket and see if it makes sense then.

DaveV

<P ID="edit"><FONT SIZE=-1>Edited by DVerbarg on 9/22/00 05:32 PM.</FONT></P>

 

[W5FL]

Harv, I don't like your dealer's definitions.

My M6800 has a seperate lever actuated clutch and brake for the pto. It does not matter what you do to the clutch, the pto is completely independent in its operation of everything except engine speed.

My Massey 245 had a dual clutch. The first position ran the hydraulic pump (stupid decision) and started the pto. The second postion when you let it out started the tractor. This was typical of live pto's.

The less expensive way is what the manual says. Your pto is tied directly to the clutch shaft and the clutch operates the tractor and pto. The overrunning clutch is simply a one way device that allows you to apply power to the pto but not to allow the pto to drive your tractor (as the last post stated) through a fence with the inertial of a mower on the pto.

My massey also had a lever to engage and disengage the pto (which I am sure yours has also). One position was at engine speed and the other was at ground speed.

It will make little difference where you are mowing large areas and most pto implements will make no difference to them. Although my Massey had a 2 position clutch, it was seldom (if ever) used except all the way in or out.

Marketing types come up with all of this dumb terminology. Fortunately they don't know how to write manuals, so the manuals usually are easier to understand.

P.s. I thought you had come up with the meaning of life!

 

[Harv]

Wen -

I have come up with the meaning of life --

Mine should be delivered sometime this weekend. /w3tcompact/icons/laugh.gif

 

[Harv]

Wen -

The page that WVBill referenced does, in fact, give an excellent explanation of all this PTO jargon and its history, and I think it supports what my dealer was telling me.

HOWEVER, what this seems to come down to is the common usage of the terms and the technically-correct-if-not-a-little-esoteric definitions. In other words, you are right and so is my dealer, but in different realities.

Uh-oh! Did I just sound like Fox Mulder? /w3tcompact/icons/blush.gif

So, like you say, if we just ignore all the market-speak buzz-words we'll all be better off. Anybody shopping for a tractor and wants to know if it has a livePTO or not, just ask him what happens when you push in the clutch.

 

[Thomas]

Harv,
After reading all your recent post you must be bouncing of the wall,/w3tcompact/icons/smile.gifand your wife I'm sure having a good time watching all your emotions. /w3tcompact/icons/wink.gif

Ahhh it wasn't all that many post ago when you wrote something like,"might wait a while before buying a Kubota"/w3tcompact/icons/shocked.gifand now that you have been bitten there no cure for you as the rest of us./w3tcompact/icons/wink.gif

Try and have a relaxing weekend.

Thomas..NH

 

[Harv]

Thomas -

Funny you should mention my wife and me bouncing off the walls. When I first heard about this L2500 being available I wasn't particularly excited 'cuz although it seemed like a very good bang for the buck, it was clearly beyond the budget we had agreed upon. Much to my surprise, my wife said, "The sooner you buy something, the sooner we can get back to our normal lives." We then sat down to review our financial situation and she summed it up with, "... the time you're spending obsessing over this thing is costing us money, so we'd be better off spending the extra money now so you can get your mind back on work." She was serious. /w3tcompact/icons/shocked.gif

All in all my wife has been quite supportive of getting a tractor, but for all you would-be tractor shoppers out there, take note of this episode in planning your strategy. /w3tcompact/icons/wink.gif

 

[Bird]

Harv, it's too bad about your wife miscalculating. She thought when you got your mind off shopping for a tractor, you'd get back to work, when in reality, now you'll be preoccupied with thinking about using the tractor instead of shopping for one./w3tcompact/icons/wink.gif

Bird

 

[gerard]

Did she also forget about how much time you'll now be shopping for implements????? The fun has just begun......../w3tcompact/icons/smile.gif