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Reliability and capabilities of 86 series closed center PFC hydraulic system


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On a 1086 with the closed center pfc hydraulic system how reliable and capable is the hydraulic system?

How reliable is the pump and system?

How about running a hydraulic spray pump?

how about my late jd750 no till drill?

How about a modern hydraulic double rake?


I am  very familiar with the 06 - 86 open center hydraulic system but have never been around the pfc system. Down here people are afraid of the pfc system and TAs.

 friend has a good 1086 with the pfc system with the hydraulic pump out. The tractor is in good condition otherwise and have considered trading him out of it. If get it i would use her for tillage, hay, and general use.

Thx-Ace 

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Our 186 has been very good with the hydro department. It has had the pump replaced once, but has overall very responsive and fast hydraulics. We have a 1086 that has the pfc, and it can be a little finiky in colder weather however. 

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All of the 86 series pfc reliability problems can be traced to lack of a charge pump. The axial piston pump relies on spring pressure to pull pistons out of bores to pull oil. That limits vacuum it can pull. To aleviate the problem they used a thermal bypass valve in the filter. That means that when starting cold. Not only is it starving for oil but the oil it is getting is largely unfiltered. A brake failure, pto clutch failure or ta clutch failure usually will precipitate a pump failure. Just like a hydro. Clean oil and filters are manditory. The hydro has charge pump but is still susceptable to cold but tolerates it better.

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The was a service bulletin. I don't remember the date. CIH offered a conversion kit to replace the pfc pump in tractors that are used for heavy pto work. Before the aftermarket did. I sold quite a few. The bulletin specifically mentions forage harvesters, stalk choppers and grinders. The problem was what IH called "torsional deflection of the driveline" Nearly every pfc pump we replaced had either a broken off gear or when you shook the pump you heard broken stuff inside it. Every one had been doing heavy pto work. 

I think for general use those pumps are ok. Like loader work. Just don't use the pto.

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I have been looking at my service manual and other stuff. I think it has the gear pump conversion. 

The return line from the auxiliary valves is a tee Instead of an elbow. I didn't think to look at the pump housing while I was there but I stood beside the tractor to look to see how many hydraulic levers it had and then looked at the valves under the cab and the plumbing. I noticed the tee and thought it was odd. I think there were two big and one small lines going to it.

Thx-Ace 

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Your better off with  the the PFC system for high demand and modern hydraulic needs of the newer equipment the older gear pump still would be hard pressed to meet the challenge 

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20 hours ago, cedar farm said:

The was a service bulletin. I don't remember the date. CIH offered a conversion kit to replace the pfc pump in tractors that are used for heavy pto work. Before the aftermarket did. I sold quite a few. The bulletin specifically mentions forage harvesters, stalk choppers and grinders. The problem was what IH called "torsional deflection of the driveline" Nearly every pfc pump we replaced had either a broken off gear or when you shook the pump you heard broken stuff inside it. Every one had been doing heavy pto work. 

I think for general use those pumps are ok. Like loader work. Just don't use the pto.

What exactly did the pto work do to the pump itself? Did the ipto gear push on the driven gear of the pump and shear the shaft off??

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2 hours ago, MinnesotaFarmall said:

What exactly did the pto work do to the pump itself? Did the ipto gear push on the driven gear of the pump and shear the shaft off??

The shaft for the PFC pump would snap off right between the drive gear and the front of the pump. Used to happen on hay grinder tractors around here…especially 14 & 1586s. Under heavy PTO loads, the drive shaft going back to the PTO unit would flex, breaking off the gear. Evidently the tolerances between the PTO shaft and PFC pump were closer than the old gear pump used on the open center systems as I’ve never seen that problem on them. 

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7 hours ago, SDman said:

The shaft for the PFC pump would snap off right between the drive gear and the front of the pump. Used to happen on hay grinder tractors around here…especially 14 & 1586s. Under heavy PTO loads, the drive shaft going back to the PTO unit would flex, breaking off the gear. Evidently the tolerances between the PTO shaft and PFC pump were closer than the old gear pump used on the open center systems as I’ve never seen that problem on them. 

I had that happen tube grinding hay and also chopping feeding with a field cutter it would break the shaft and then damage the teeth on the IPTO drive gear had to be very careful after that I decided it wasn't worth the agony and went to using a 4440 JD for high torque pto work

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Well that takes up a question I was always thinking about. A neighbor had a 1066 that would always busy the hydraulic pumps up if he used it on the mixer. I told him that it shouldn't matter because the pto pump and the hydro pump are two completely different pumps but driven off the same gear. He said it would usually happen when turning and it would really lug down the tractor. I told him he must have a bearing out on the mixer or a bad u joint. He replaced the joints and had no bearings out on the pto. Now, knowing what I know, I bet it would bind the PTO shaft a little bit and make it flex a bit and would send the hitch pump out. 

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So, if you avoid heavy pto work they work well. I expect a good hydraulic fluid helps too.

What about capabilities?

Hydraulic spray pump, jd 750 no till drill, hydraulic bar rake?

Thx-Ace 

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You didn’t specify what kind of bar rake you intend to use, I’m going to assume something like a Vermeer Twin Rake. I don’t know why you would have any trouble at all running something like that with an ‘86 PFC pump. The hydraulic requirements are pretty modest on the Vermeer rakes, 8 gpm and 2000 psi will get the job done. We ran an R23 and R2300 with a 686 and now a 766 for more than 20 years. If they can do it I sure think a PFC 86 will work fine. 

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Our 3588 got the conversion kit when we fixed it up right after we got it . Glad we did as we used it for a mixing tractor, HARD on the PTO

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Here is the verbage of the bulletin that Cedar Farm referenced. Explains it pretty well. As far as comparing the capacity/ability of the PPH system to the hydraulic capacity/capabilities of today's tractors....don't get your expectations too high. Its really comparing apples to oranges. Back then, most hydraulic motors were simple gear motor setups that didn't need a lot of pressure to operate...didn't take much power and didn't create a lot of heat. Today's hydraulic motors are usually of axial-piston design which take more pressure to operate and create more heat...although their overall efficiency is much higher. The hydraulic cooling capacity on tractors with PPH systems was much less capacity that what today's tractors offer. The PPH system allowed a transition away from open center hydraulics to modern closed-center hydraulics, but closed-center load-sensing hydraulics were still in their infancy at that time...we've come a long way since then.

To give you an idea about this, a Cyclo planter hydraulic motor took 7-8 GPM to operate the blower fan. IH(and later CaseIH) did NOT recommend using a PPH-equipped tractor to run the Cyclo system directly off the tractor's hydraulics due to limitations of the PPH system.

PPH conversion.PNG

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Here's a question. If the ipto shaft flexing would cause the pump shaft to break because the tolerances were so close could a person possibly cut a gasket for between the pump flange and the rear case out of a thicker material to add a little more gear lash?

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