What is a "live" PTO?

Hi Brandon    (Brandon isn't asking me these questions because HE doesn't know the answers. He is checking up on me to make sure that I know.)
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Hi Meli,
    Ever thought about explaining "Why my PTO stops" on the "Tip of the Week"?

Okay Brandon,
    That's a good idea! I'll use the Model B as an example. There is a little lever near your right foot that engages the PTO. This connects it to the gears of the transmission. But still, it won't turn unless you engage the clutch of the tractor. Try it. Engage the lever, put the transmission lever in neutral, and engage the clutch. See? The PTO turns. Of course, it will also turn whenever the transmission is in gear and the tractor is moving, but it will stop when you disengage the clutch. If you want it to keep turning, you must quickly shift the transmission to neutral and quickly engage the clutch again.

    Now, can you explain a Live and Non Live PTO?

Pay Attention!!!     That's a good idea, TOO! The trouble is, the newest tractor we have ever had on this farm is a 1950 Model B. We have never used a live PTO and don't know exactly how it is set up. I DO know that there is another train of gears and another clutch, but I don't even know WHERE the clutch is located and what it LOOKS like!! If you are familiar with the live PTO, would you tell us a little bit about it?

    Okay... Some live PTOs may be set up different, but I will describe my JD 80, which has a live PTO. The controls will also be different from tractor to tractor. There is a shaft that runs from the crankshaft to the rear of the tractor (Of course it turns all the time) Between this shaft and the PTO is a clutch that can be engaged and disengaged to start and stop the PTO when needed, which is controlled by a lever by the hand clutch. It is totally independent from the main tractor clutch. Some JDs were able to completely disengage the live PTO from the engine if you weren't going to use it. My 80 can't do that. The main advantage of Live PTO is that you can stop and start moving the tractor, without stopping the PTO. You probably noticed that when you stop your B, the sickle mower stops. Live PTOs are great for balers when they start to overload! Stop the tractor, let the baler run the hay through, then start again.

Go slow     Yes, many times with the mower, when you get into a heavy cut, you wish you could "ride the clutch" on the tractor, to slow down and let the mower catch up, but unfortunately this slows down the blades on the MOWER, too!!

    And why shouldn't you brushhog near trees with a non live PTO?

    Okay, tell me about THIS too! We mow with the No.5 sicklebar and we have several trees we have to go around. There is never a problem. Is there something WORSE about brushhogs?? If you haven't guessed it, we don't have one of THOSE, either.

    Well, the brushhog has blades like a lawn mower, and most brushhogs are about 5 feet wide. Those long blades take quite a while to stop after they get going (momentum)! With a non live PTO, the PTO is driven from the transmission gears. While using a brushhog, if you try to stop by pulling back on the clutch (or stepping on the pedal), you will stop and disengage the engine from the transmission, BUT!! the brushhog will continue driving the tractor forward (the brakes won't do much to help)!!! And if you have an obstacle in the way, that might be a problem! The only way to stop moving is to disengage the PTO, or slip the tractor out of gear. With live PTOs, this is not a problem, since it is not driven from the transmission.

    Oh, I see. Since the PTO is still connected to the transmission and ultimately to the wheels, the brushhog continues to turn the transmission. I suppose if you had the presence of mind to disengage the PTO lever at the same instant that you disengage the clutch, you WOULD be able to stop. But WHO can think that fast!!

    Here is a drawing of a live PTO out of a model 50, if you'd like to show it to everybody. It is set up totally different from my 80!

Here it is....

Pay Attention!!!

    Yes, I can see that the powertrain to the PTO is completely independent of the powertrain from the engine to the wheels. This was one of the big selling points of the "First Numbered Series" that replaced the "Letter Series" in 1952.
   THANKS Brandon!!

    You're welcome, Meli.

Hi Brandon     You can see Brandon's Industrial John Deere web site by clicking HERE.

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"Poetry in Motion"
Johnny Tillotson, 1960