PTO newbie question

[GeauxLSU]

OK, since I've yet to get an decipherable answer, can somebody please spell out in newbie terms (meaning 'ignernt') the difference in the types of PTOs? Meaning Indepent vs. Live and the various sub categories?
What are the advantages disadvatages of each and what would you get and why?
Thanks in advance.

 

[mchasal]

I started to type a whole explanation, but just read this: http://www.tractorsmart.com/main/Tractor Power Take Off Types.htm

Mike

 

[Soundguy]

OK, since I've yet to get an decipherable answer, can somebody please spell out in newbie terms (meaning 'ignernt') the difference in the types of PTOs? Meaning Indepent vs. Live and the various sub categories?
What are the advantages disadvatages of each and what would you get and why?
Thanks in advance.

Transmission pto: A non live pto. When you step on the single stage, single plate clutch, your drive train and pto stop. In neutral, you still have pto. When in gear, the pto is tied to the drivetrain thus rotary inertia from a mower can push you ahead with the clutch pushed.. so you need an over running coupler ( 1-way ratcheting device ) to prevent backfeed.

Ground speed pto: Another non live pto that is tied to the drive train. As the wheels spin, so does the pto. many farmimg applications used this. Some MF tractors had this option. It matches the pto speed to a gear and ground speed. Thus.. you wheels must be turning for the pto to spin... No stationary pto apps.

Live pto: Generic term. It means you can keep the pto spinning while stopping the drivetrain. Can be accomplished several ways:

2-stage clutch. Cheapest. Clutch has 2 sections.. stepping onthe clutch partway disengages the drivetrain but leaves the pto coupled.

Independent: A tractor with an independent pto usually has a single stage clutch that clutches the drivetrain*, and the pto section is either electrically(electric over hydraulic ) or hydraulicly engaged with a lever, using it's own clutch. Because of this seperate clutch, the pto can be engaged / disengaged 'independent' of the drivetrain.. thus you can engage pto on the fly.. whereas a 2 stage clutch design must be fully clutched to engage the pto. (* HST trannies are an example of an independent pto where a single stage clutch may not be present. )

Lastly.. Full hydraulic pto... this would also be considered live, and independent depending on how it was plumbed. In this setup, the pto is nothing more than a hyd motor with an output shaft that is the tractor's pto stub. The tractors' engine runs a hyd pump that supplies the pto motor with oil.. etc. I believe 'power-trak' equipment are all hyd.. that is.. the 4wd is powered by 4 hyd motors, and the pto is fully hyd as well.

Any other questions.. i think i hit the high points.

Most pto's only spin 1 direction. There are a few exceptions.. that is.. some machines can spin the pto backwards.. etc.

Soundguy

 

[N80]

Excellent summary. Now a somewhat unrelated question:

One of my B-I-L's bigger JD tractors has two PTO shafts, but one of them sticks out towards the right side of the tractor in the same axis as the rear axle. The 'normal' has typical looking splines and sticks out towards the rear. The sideways one has more and smaller splines. When I asked him what the second one was he just shrugged his shoulders and said he thought it was just a holder for a different type of PTO shaft that could be exchanged for the normal one. But he didn't sound sure...he's only had this tractor for 25 years!

He might be right, but it sure looked like the sideways one was sealed where it entered the housing. He said it does not turn when the other one does.

 

[Soundguy]

If you would post the tractor model number it would help.

My 2 guess's.

1, Your BIL was right.. it is the 1000 rpm pto shaft.. which does have more splines.. and JD made a convienient place to store it. Many large tractors usually category 2+ have a 2 speed pto option that is changed over by removing the pto shaft and installing a different shaft that runs on a different gear set int he opening. Usually the pto shaft has it's own seal, and perhaps bearing, and the assembly slides in.. perhaps with a split ring holding it in. My NH 7610s has a 2nd shaft that can be swapped in to let me use 1000rpm pto implements.

2nd guess is that it is for a side belt pulley.

Soundguy

 

[GeauxLSU]

Thanks for the summaries guys. I think I understand it enough to be dangerous.

what would you get and why?

 

[N80]

The second PTO shaft definitely looks like the 1000 rpm PTO shafts I've seen pictures of so I guess you (and he) are right.