Dear Ole Mechanic;
You have covered tractor problems in the past and you seem to know a lot about tractors. I need for you to settle an argument between my friend and me. I am not going to tell you what either one of us believes, as we are looking for an unbiased definition. There is a steak dinner riding on this, so--What is a “live" PTO?
Dear International Harvester Fan;
A "live" Power Take Off (PTO) is one that can operate independently from all other tractor functions, as long as the engine is running. The engine speed does effect PTO speed, and there is normally a separate clutch to engage and disengage the PTO.
I will give you an example of a non-live PTO. The best known non-live PTO would be the 1939 through 1952 Ford N-Series of tractors. The ‘N’ tractors have the PTO driven off of the transmission. If you step on the clutch, then the transmission gears will stop turning. If the transmission gears stop turning, then the PTO stops turning. The best example of how this could be a problem would be if the tractor was pulling a PTO-driven hay baler. If you were moving through a hay field and came upon a large bunch of hay in the windrow, you could not slow down to keep the hay from plugging up the baler. If you slow down the engine, the transmission and PTO also slow down, making it more likely that the baler would plug up. What you would need to do is push in the clutch, wait for the transmission, PTO, and baler to stop. Then you could select a lower gear. As you let out the clutch the transmission would start along with the PTO and baler. Once you got past the large bunch of hay, then you would step on the clutch, wait for things to stop, select a higher gear, and then let out the clutch to start baling again. With a live PTO--which is what most newer tractors have--you could get close to the big bunch of hay and then step on the clutch to slow the forward speed of the tractor and baler. Since the PTO speed would not depend on anything but engine speed, the baler would stay at operating speed while the forward speed slowed down. Simply by slipping the clutch you could ease into the big bunch of hay slowly, so that it didn’t plug up the baler.
While a tractor that could pull and also power the pulled piece of equipment was a major advancement in farming, the further development of the “live" PTO really made the tractor much more useful. As I stated right up front the “live" PTO will operate independently of all other tractor functions except engine speed. I hope that you and your friend enjoy the steak dinner no matter who buys.
Herr Professor Nuzanbolts