Help ordering hydraulic fittings (for rear remote)

[rswyan]

The goal remains ..... To put QCs on the the middle valve, that it may be used.

Absolutely nothing wrong with that.

In fact I am still wondering what is the REAL effect that will be made - by adding the PB circuit. I hear "its better", it's the "correct way" to do hydraulics (nowadays). I would like to know, what is the specific detriment to leaving it "as-is".

That question has been asked and answered ... repeatedly ...

Is it clear to you now ?

Or are you still wondering ?

Sorry I just have to know these things, it helps me to understand.

Knowing something implies certainty.

In that respect, you have a difficult "row to hoe" so to speak - owing to a (previous) unfamiliarity and lack of knowledge about hydraulics ... and your own natural skepticism ...

Nothing wrong with a some degree of skepticism - it's natural and healthy.

But it can be taken to extremes.

 

[Sodo]

OK I'm back out in the mountains and here's whats inside the "OUT" port.

Down at the bottom of the hole there is a thread that's about 1/2" diameter, they are barely visible in the picture. (Not referring to the reflection image on the oil surface).

From this pic, can anybody tell me is this port likely configured for a PB adapter? If you think so I will start chasing Dinoil for one.

That question has been asked and answered ... repeatedly … Is it clear to you now ? Or are you still wondering ? Knowing something implies certainty. In that respect, you have a difficult "row to hoe" so to speak - owing to a (previous) unfamiliarity and lack of knowledge about hydraulics ... and your own natural skepticism ...
Nothing wrong with a some degree of skepticism - it's natural and healthy.
But it can be taken to extremes.

Well skepticism of wht you read on the internet is essential, in my mind. Forums are not really the best way to learn stuff, you don't see threads quoted in user manuals, for example. But I sure learn lots on forums (when able to drill down to the truth).

Regarding the "discussion" whether it's "acceptable" to have hi-pressure in a return circuit, here's a pic of the seal on the "OUT" port. It makes sense that this seal arrangement (where there's an o-ring pressed down by a washer) is intended only for a low pressure "return to tank". I don't know what other reasons there are but this has to be one of them.

 

[BukitCase]

The good news - I can see no other reason for internal threads lined up with the outer ones EXCEPT for a PB adapter - the (sorta) shiny circle just ABOVE the inner threads would be the sealing area for the inner O-ring. I'm about 97.5% sure you need to bug Dinoil now

But - "It makes sense that this seal arrangement (where there's an o-ring pressed down by a washer) is intended only for a low pressure "return to tank". -

NOT so - That's a standard SAE O-ring Boss fitting, got bigger ones just like that all over my Case, runs @ 2300 psi. One advantage of those is that, unlike TAPERED threads, you can aim the other end of the 90 ANY direction you want, then just tighten the locking nut/washer and make your seal.

Didja ever find a part # on your valve anywhere? If not, it's probably gonna be about as much fun as a poke in the eye with a semi-sharp stick Then again, you might get lucky and find the one person at Dinoil that WON'T ask you (in Italian) "Would you like fries with that??!?"

BTW, I'm guessing that the OTHER, blocked, port NEXT to the one in the pic DIRECTLY connects to that sideways hole I see ABOVE the inner threads - if so, that'd be your new "Tank" port once you find the adapter.

BTW, I just retired a couple years ago from working Instrumentation and Control in heavy industry for the last 35 years, ran a full maintenance crew for the last 10 - If that ain't enough "non-internet" creds for ya, figger it out for yourself ... Steve

 

[Sodo]

Well those SAE O-ring Boss fittings are handy. Makes a guy wonder why there's any other type in use.

,,,with the PB adapter in place, if you don't move any levers in the valve body, flow ONLY goes thru the PB adapter and on to the next valve in line, and finally to tank. (still at high pressure, but ONLY if you're actuating a valve (to a toplink, for example) -

In a typical open center system, when you actuate ANY cylinder from ANY valve, flow is re-directed - either to the "A" or "B" WORK port - whichever port (A or B) is pressurized, the OTHER work port gets routed to the Tank gallery to relieve pressure on the other side of the cylinder's piston - otherwise, the cylinder can't move.

Without a PB adapter in a control valve, ALL the pump flow just goes IN the Pressure port and OUT the Tank port UNTIL you move a lever, and a gauge placed ANYWHERE in that path will only read as much pressure as would be caused by various restrictions in tubing, hoses, open valves, etc.

WITH a PB adapter installed, the TANK port only feeds back to tank when a spool on THAT valve is moved - otherwise, ALL fluid continues on thru the circuit thru the PB adapter.

Not sure I cleared up ALL your questions, but hopefully it's a start... Steve

Still trying to digest this, but I think I need a diagram or schematic before I'll actually get it. Or someone waving their arms and pointing at my tractor hydraulic system.

Disadvantage of leaving it like it is - maybe nothing, but it's more likely that (if your system is NOT plumbed to the correct ports) the tank seals just haven't blown YET.

-----IF that output is going ANYWHERE but back to Tank, you should have a PB adapter there - otherwise, odds are REALLY good you will eventually (if not already) have messed up seals in the valve.

----follow the basic rules - high pressure lines should ALWAYS go from Pump to Inlet, Tank ports ONLY go to tank (and may be teed), Outlets to the NEXT device ALWAYS come from PB ports EXCEPT for the last device in the path, which can/should be a Tank port which ONLY returns to Tank.

What are "tank seals"? There's the filler cap, dipstick & drain plug, and all at zero pressure.

What seals in the valve get messed up? I can imagine full pressure between the spools, and a leakage gallery between the spool & outside seal. If this leakage gallery rises to full pressure due to a downstream component the seal experiences full pressure, and you're saying these seals are designed for return level pressures only (0-500). So,,, my 3-pt hitch being downstream,,,, maybe there's been no problems because the 3-pt hasn't lifted full capacity?

Sorry until I can find a cutaway valve & open center flow diagram I think I'm just going to remain a little mixed up.

Found a good thread where a guy (eventually) plumbed his remotes like mine (no PB). Different explanations of the same subject was useful to me..

 

[BukitCase]

OK, I think we're getting closer - gonna see if I can clear up/re-state a couple things...

First off, I probably shouldn't have referred to "Tank seals" - they are really the seals that keep LOW pressure fluid from finding a "sneak" path out the ends of the valve where the spools move back and forth - And, as mentioned earlier these seals are only intended for lower (under 500 psi typically) pressures, cost being the (probably) main factor.

Please download this http://www.princehyd.com/portals/0/techFAQ/OpenCenterPbDA.pdf for reference -

So, in a power beyond circuit with nothing activated (first diagram), you have essentially no high pressure in the circuit except for unknowns which are ISOLATED from everything else by spools being in neutral position (no flow to or from any WORK ports)

The pump is moving fluid, and technically NOTHING is at ZERO pressure, because any time you have FLOW you will have pressure DROPS across every resistance, no matter how slight. However, the pressure under these conditions is very low compared to a work port being opened (valve lever being moved)

Under these conditions, NO PART of the valve other than WORK ports (if that) will see high pressure.

Second diagram - One work port actuated, pump develops pressure out the work port and into the cylinder - this diagram ***-U-ME's full actuation of the valve so ALL pump flow/pressure is directed to the cylinder - that's why the Power Beyond path is shown in WHITE, with no flow.

Third diagram - This shows using the Tank port of the first valve for Power beyond, conditions being that the SECOND valve is being actuated to drive a cylinder - this puts the FIRST valve's IN and TANK ports both at high pressure - you can see from the little blue "tear drops" WHERE the leakage may happen - here's why...

Hydraulic spool valves are made with REALLY tight tolerances so they don't need INTERNAL O-ring seals - typically less than a thousanth, some only 2-3 TEN thousanths of an inch clearance between the spool and its bore - under typical usage (no power beyond), the relatively low tank gallery pressures can be contained by O-rings at the OUTER ends of the spool pieces, and spent fluid can just take the path of least resistance back to tank -

BUT - if internal tank gallery pressures exceed the relatively low levels needed to return spent fluid back to the tank, these O-ring seals will start to seep (or worse) -

So, what the Power beyond adapter does is to MAINTAIN the higher pressure capability of everything in the valve EXCEPT the two outer ends of each of the spools (where the TANK gallery is) - this allows high pressures to build up downstream of the first (power beyond equipped) valve so the NEXT valve in the circuit can operate at high pressure WITHOUT blowing out the outer spool O-ring seals of the PREVIOUS valve.

Until you've had one of these valves apart, it's not very intuitive how they work (or, schematically, what those little squares with "X"s or straight lines between the lines shown coming INTO the outsides of the boxes mean) - keep in mind that those "spools" are not just a straight rod that's all the same diameter - different sections of a spool will have portions turned down on a lathe - when that spool is in its neutral position, the smaller diameter sections will be lined up with in and out ports so fluid just passes thru to the Tank port and back to tank -

When you MOVE the valve, the full diameter sections block off some flows and re-direct others to the Work ports, while re-directing the OTHER work port to the Tank gallery (and back to tank) -

Schematically, when you see a line going into a block and there's only a T on the end of that line with nothing drawn across the block to the other side, it means that the spool is NOT allowing flow thru that line in that position.

An "X" shown inside the block shows what the flow will be when the spool is moved to that position. Typically the OTHER position of that valve will show two PARALLEL lines, but not always - depends on the function of the valve.

I've probably missed a few dozen points here, but it's tired and I'm late Gotta hit it again manana, got brush forks to modify and a Samurai to finish plumbing... Steve

 

[J_J]

Sodo,

There no reason for this post to go on as we have told you what is wrong and how to fix the problem.

Do you not believe what we have told you?

There is no logical reason for not using the PB port with adapter.

Tank ports just simply go to tank.

Just because someone connected things up wrong doesn't make it right, and any day, a new valve may be in your future.

 

[Discount Hydraulic Hose]

SAE Straight Thread O-Ring fittings (aka O-Ring Boss or ORB) are actually designed to prevent leaks at HIGHER pressures than tapered pipe threads in most sizes. They are also preferred in many situations, because the threads are not deformed and can disassembled and re-assembled without any degradation in the integrity of the seal. Someone already mentioned that the elbows and tees are adjustable so they be positioned in any direction or rotated 360 degrees and tightened in place. This fitting is so common in hydraulics that many people simply refer to it as "SAE"

SAE Straight Thread O-Ring (ORB) Hydraulic Fittings

 

[rswyan]

OK I'm back out in the mountains and here's whats inside the "OUT" port.

Down at the bottom of the hole there is a thread that's about 1/2" diameter, they are barely visible in the picture. (Not referring to the reflection image on the oil surface).

From this pic, can anybody tell me is this port likely configured for a PB adapter? If you think so I will start chasing Dinoil for one.

I'd concur with BukItCase ... given the number of holes for ports on that end, and the machining inside the one, it looks like the valve is power beyond capable with an adapter.

Well skepticism of wht you read on the internet is essential, in my mind. Forums are not really the best way to learn stuff, you don't see threads quoted in user manuals, for example. But I sure learn lots on forums (when able to drill down to the truth).

Like I said previously: there's nothing wrong with a healthy dose of skepticism.

All things in moderation however

What is really important, is that one gains an increased understanding of whatever subject is being addressed.

Regarding the "discussion" whether it's "acceptable" to have hi-epressure in a return circuit, here's a pic of the seal on the "OUT" port. It makes sense that this seal arrangement (where there's an o-ring pressed down by a washer) is intended only for a low pressure "return to tank". I don't know what other reasons there are but this has to be one of them.

Covered by others already ...

 

[Sodo]

There no reason for this post to go on as we have told you what is wrong and how to fix the problem.
Do you not believe what we have told you?

J_J ( & RS & Bukit ), I think this discussion drug on due to the lack of diagrams.

I have a desire to actually understand this (perhaps common) tractor problem, and appreciate your patience. I'm sorry if it appears I just don't believe. Sorry - I gotta KNOW.

I have worked "very close" to hydraulic design circa 1990. We were studying sedimentation (sediment packing into that 2-3 tenths and jamming servo-operated spool valves - and linkage operated too!) so I do have an understanding, just took awhile for my memory to dredge up the proper files .

I honestly appreciate that this thread has gone on,,,,and on,,,,and on,,,, Because I GOT IT NOW. :cool2:

<<< Sodo >>> What seals in the valve get messed up? I can imagine full pressure between the spools, and a leakage gallery between the spool & outside seal. If this leakage gallery rises to full pressure due to a downstream component the seal experiences full pressure, and you're saying these seals are designed for return level pressures only (0-500). So,,, my 3-pt hitch being downstream,,,, maybe there's been no problems because the 3-pt hasn't lifted full capacity?

Steve here you are explaining what I tried to imagine (above).

<<< Bukitcase >>>>Hydraulic spool valves are made with REALLY tight tolerances so they don't need INTERNAL O-ring seals - typically less than a thousanth, some only 2-3 TEN thousanths of an inch clearance between the spool and its bore - under typical usage (no power beyond), the relatively low tank gallery pressures can be contained by O-rings at the OUTER ends of the spool pieces, and spent fluid can just take the path of least resistance back to tank -

I've got it. High pressure diverting happens with 'metal seals', which don't really 'seal' but the leakage is managed. A device down the line, if used (to stalling loads) will pressurize this 'leakage' gallery to full pressure, and it's intended to just bleed this (managed) leakage to return. The reason systems configured like this "haven't failed" (yet) is because:

1) The device down the line (often 3-pt) may just be used to lift items far below it's full capacity, and rarely stalled. And thus doesn't often pressurize upstream to the "OUT" to 2300psi.

2) If the middle valve (the one in danger) by chance (or luck) is not operated often during this offense your seals may last longer. If you operated the valve lever (sliding the spool) under while the 3-pt was using all 2300psi you would be 'working' these seals while they are energized under full pressure, they could be damaged more each time these two implement events overlap. If you have a combination of implements that never overlap these 'offenses' your 2nd valve MAY survive awhile. If your combination of implements cause you to operate the '2nd valve' often (while the 3-pt is at 2300psi) your 2nd valve EXTERNAL seals may fail shortly.

Here is a textbook example of an attachment that could pressurize the 3-pt hitch to its max pressure. A heavy weight is on the forklift attachment - which being supported by the 3-pt hitch - subjecting the external o-rings of the upstream valve to 2300psi. Then the operator slides the spool back to raise the forks while it's o-ring seals are subjected to 2300psi! The valve is being slid thru seals that are energized FAR beyond their design capacity. This is why all valves upstream of the 3-pt need PB. Valves downstream of the 3-pt are not considered because the 3-pt valve is often internal to the rear tractor case thus nobody ever adds a valve downstream of the 3-pt.

============

I've modified the 3rd pdf of the Prince diagram (linked to by Bukitcase) but the TBN image uploader is having its own Power Beyond problems at the moment. Will add it later.

 

[BukitCase]

Worked on/with a few linear servo valves myself, being used to run a smallish hydraulic motor which ran a ball and lead screw drive which raised/lowered a titanium or zirconium electrode (weighing around 10 tons) into a vacuum arc melting furnace putting out up to 50,000 amps - the servo got its signal from a voltage comparator, and its setpoint was set by the operator (later by computer) to maintain the proper arc voltage for the specific alloy being melted...

We had so much trouble initially with jammed servo valves I had the pipe fitters add two more filters just for that application - ended up with 50 micron followed by 10 micron followed by 2 micron before the problems stopped... Steve

(For those who got lost, 2 microns is 2/1000 of a millimeter, which works out to 0.00007874 inches)