1970 4020 synchro PTO doesn't stop

[lka]

Hi folks. Just picked up a 1970 4020 synchro serial 223XXX. Previous owner put a new clutch in it a few months ago. Tractor runs and drives fine, all gears work. Has a few other issues though. Biggest one is that once engaged, PTO will keep spinning even when the (hydraulic) PTO lever is pulled all the way back. It still spins at full speed.

I am told that (1) it worked fine before the new clutch was installed and (2) that the PTO will stop properly if connected to a decent load. I have not tested this latter point yet but I do recall the PTO was not spinning when I went to look at the machine before sale so it can be stopped somehow. The new clutch was installed by a fairly competent heavy equipment mechanic with a few specialty tools borrowed from the local JD dealer.

The PTO shaft *cannot* be spun by hand with the tractor off and the PTO disengaged.

Finally, I'm not certain how the PTO lever is supposed to work. I have an owners manual but it is for an older machine and describes a lever that comes out of the left side of the cowling -- mine is the hydraulic style facing you and located just left of the steering wheel where the SCV controls used to be. It only has two positions at which the lever will stay in place, all the way rearward at full travel (brake engaged?) and all the way forward (PTO engaged). Is there supposed to be a middle position which is PTO disengaged but without PTO brake applied?

Is there a chance that this is just a linkage issue? I do not yet have a shop manual but am in the process of finding one. Thank you kindly!

 

[lka]

I got the shop manual today and went ahead with adjusting the linkage to the PTO valve. Unless I am missing parts or something came assembled wrong with my linkage, there is no way to maintain the lever into the "neutral" position or even a good way to know where neutral is supposed to be -- it ether over-centers forward into engaged or is pulled all the way rearward with spring pressure into "brake". On my setup (1970 year) there are only two springs, one long thick and one thin nested inside it, both running from the linkage on the adjustment rod near at the valve end, to the adjustable eyebolt in the slot near the top bracket.

I did these adjustments with the tractor off. Does hydraulic pressure play a role into maintaining the lever at neutral? With the tractor off the valve itself moves freely without resistance from a hard stop at full extension (piston off) to a stop at the bottom, though you can apply additional pressure against what feels like a compensator spring to sink it down another 15mm or so and at this is where it is adjusted. It could be there are issues elsewhere and the linkage is fine...

 

[Tx Jim]

Shown in photo below is info related to operation of 4020 pto lever.

 

[lka]

Thank you. This is complicated somewhat by the fact that this linkage seems to have changed 3-4 times over the course of 4020 production. Later console units (250XXX+) have a dedicated brake return spring. Mine only has a spring loaded pin, and my interpretation of the the technical manual (see below) is that when adjusted in full brake position the spring will only be compressed 1/8" which doesn't allow a lot of travel for brake operation nor does the spring return the lever very far forward. I'm not sure how that doesn't just result in the brake being continuously applied. There are no obvious detents in the valve travel to tell me where neutral or brake are supposed to be.

 

[fdt860]

Have you checked for free play between pto.clutch fingers and clutch release stop? (Trough opening under clutch housing)?

 

[lka]

With the tractor off, nothing is contacting any of the transmission or PTO fingers on the clutch. It is a little harder to tell when the tractor is running. The two PTO pistons are completely retracted with the PTO lever off. I couldn't find the PTO brake piston but I wasn't exactly sure where to look or if its on the transmission side.

Related note, the clutch inspection cover was missing entirely when I received the tractor and the clutch pack and everything in there are amazingly filthy with grime and road dust, and the pressure plate is rusty -- its clear they at some point forgot to replace the cover after doing the clutch work which doesn't inspire confidence in how well the work was done to begin with. The pedal was also way out of adjustment. The drive clutch at least does work well and the transmission is tight.

I also have a very slow oil leak from the engine side somewhere but I don't have the angle to see from where. Main seal perhaps?

 

[fdt860]

(quoted from post at 21:15:51 10/04/23) Have you checked for free play between pto.clutch fingers and clutch release stop? (Trough opening under clutch housing)?

If pto does not spin with engine off and fingers are released you have to inspect the clutch first.

 

[lka]

(quoted from post at 22:12:40 10/04/23)

(quoted from post at 21:15:51 10/04/23) Have you checked for free play between pto.clutch fingers and clutch release stop? (Trough opening under clutch housing)?

Thank you. PTO shaft is locked in place with the engine off. I'm going to have to split it at the clutch I guess. Never split a tractor before. I watched a video. I think this is doable.