Some info on different clutches and types of pto - pics

Ultradog MN

Well-known Member
Location
Twin Cities
A couple of questions get asked from time to time about the different types of PTO.
So while I was working on a tractor here I thought I would snap a couple of photos and give some info on how they work.
We are all familiar with a tractor with transmission pto so I wont go into that type here.
There are two types of "live" pto.
Both are accomplished by means of dual input shafts into the transmission.

100_1537.jpg



The outer, larger splined shaft is the pto input shaft.
The smaller one drives the transmission and rear wheels.
This is the same on both "live" and "independent" ptos.
The difference is in the clutch. (And what lies behind the tranny which I wont go into here.)
This photo is of an independent pto clutch.
Notice the splined hub in the center.
This hub is rivited directly to the back of the pressure plate. So any time the engine is turning it is transmitting power to the outer input shaft, through the tranny to the pto.

100_1539.jpg


Here is the back side of that same clutch.

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On a "Live" PTO machine the dual input shafts are about the same. But the pressure plate contains TWO clutch discs. When you press the pedal down half way the main drive clutch disc is disconnected and the tractor stops forward motion.
But the pto continues to turn.
Then when you push the pedal all the way down the pto clutch disc is released and the pto also stops turning.
Here is a photo of a Live pto clutch with the two discs.
It is much more complicated than either transmission or independent pto clutches and thus considerably more expensive.
You can see the large hub in the pto disc.

100_1542.jpg


Here is a photo of both types of clutches side by side.

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A lot of times people get these two types confused or maybe don't understand how they work so while I had the parts here I thought I'd make a post about it.
 
Good info. Thanks. I had kind of a vague idea of the differences between the two. Your post shed some light.
 
Good idea UD, A few pictures really help.

Here are some from a hundred series double clutch. A bit different.

Clutch with two sets of forks, each set at a different height.



Input Shaft



Input Shaft taken apart

 
Sure did replace the seals Ultradog. That and the destroyed clutch, throw-out bearing, fork and TO bearing housing. Fun split. Had to cut off the fork and make a new pin.

BTW, the seal was leaking badly. What a mess.
 
Bill, your 861 clutch should be exactly like my photos above. Might be minor differences in the clutch but very similar.

Actually replacing this clutch is straightforward. Just expensive
 
Looking at your clutch again this AM it is very revealing how it works with the two sets of fingers. It is much easier to understand than the one I posted which is all done internally.
 

I don't know what good it will ever do me... If I remove a known good unit I make tools to measure it bolted to the flywheel for finger height reference later on down the road...
 
I was thinking the same thing Ultradog. The way yours work is not obvious. In fact I can't see the smaller splined hub in either one of your clutches. Mine is there behind the larger one, but hard to see.
 
You can't see them cause they aren't there :)
I just snapped photos of the PPs
I figured everyone understood how the drive clutch works and focused on the secondary/pto output.
By the way, those sure are pretty pink springs on yours. I'm jealous.
 

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