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. | What is the difference? I know my red tractors have open center hydraulic systems, and the Oliver 1855 I used to have and the 4430 have closed hydraulics. My son went out and bought a John Deere 1750 (i think) VRT planter this spring. From what I can tell the John Deere is the only one he can use on this planter due to the closed center hydraulic system. Is there any kind of get around to use on open center systems like a PTO pump? I am thinking of purchasing another tractor and it will probably not be a John Deere, but I would like it to be capable of being the planter tractor.
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ND | The JD pto pump will run one Vac but with an old style open center tractor if you placed an orbit motor on planter for Liq Fert the open center tractor would lose its hyd pump in short order. All orbit motors used by farm tractors need closed center-if your against JD buy a MF 1105 or 1135 or 1155 or a White 2-105,,or a 135 or 155 or 180 or a Case 2290 or larger Case tractors in this series. |
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Lincoln, North Dakota | Open center hydraulic system used a fixed displacement pump like a gear pump and are protected by a relief valve. They have constant flow. Any valves used with open center have to have an open path back to return while in neutral. Closed center hydrualic systems use pumps that are variable displacement or on demand. In closed center hydraulic systems there is no open path back to return untill a valve is moved. When the hydraulic valves are in neutral and there is no demand for flow the hydraulic pump operates in a standby mode untill there is a request for oil flow.
Edited by thorfarms 6/2/2017 08:22
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E. CO, exactly half way between NE and OK | I think my White 135 is open center hydraulic and my Case IH 7110 is closed center. |
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| Open center (Simple) - think of a gear pump - to gears meshing together pushing fluid through. The valves in open center systems allow flow to go through them all the time. When you use a valve it redirects the flow to the outlet. If the flow dead heads, a relief valve will open and allow flow to go through. Usually this makes a high pitch whine noise when the relief is open. Without the relief valve something would break.
Closed center - the pump is a version of the hydro pump on a combine where it controls how much it pumps (on a combine, the hydro lever controls flow and pressure usually determines flow on a closed center tractor pump). The valves in a closed center shut completely off when flow isn't needed and direct flow to the cylinder etc. when you use the valve. The pump senses the drop in pressure (or other factor) and starts pumping more fluid (takes milliseconds). When you shut the valve the pump senses the rise in pressure and shuts down. Closed centers have a relief as well in case of an over pressure situation (something broke or ?).
Older tractor used open center systems because it's simple and cheap. The drawback is fluid is always chasing through the system and that takes power and creates heat. The closed center system is more efficient. Most of the time, planters, etc. don't care which system supplies hydraulic pressure. You can get into situations where you need to reduce the flow to a fan or similar and if it's enough, the pump will see the port as closed and shut down. A lot of times fans use a bypass line to allow a little more flow and to allow the fan to coast to a stop when the hydraulic valve is closed.
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NW KS/ SC ID | wht one - 6/2/2017 07:39
I think my White 135 is open center hydraulic and my Case IH 7110 is closed center.
Your White 2-135 has a Flow Compensating Closed Center hydraulic system. Similar to JD. Allis was the first and the only for a while, with a PFC (Pressure and Flow Compensating) Closed Center system.
Oliver came out with closed center on the 55 series, so All White products (over 100 hp at least) will be closed center.
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E. CO, exactly half way between NE and OK | Bill, I didn't know that, how do I adjust the flow rate on the White? |
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E. CO, exactly half way between NE and OK | jdbob8100 - 6/2/2017 07:10
The JD pto pump will run one Vac but with an old style open center tractor if you placed an orbit motor on planter for Liq Fert the open center tractor would lose its hyd pump in short order. All orbit motors used by farm tractors need closed center-if your against JD buy a MF 1105 or 1135 or 1155 or a White 2-105,,or a 135 or 155 or 180 or a Case 2290 or larger Case tractors in this series.
I think you can use an open center hyd system on a hydraulic motor if you use all the oil it pumps. We ran a hyd fan on a Flexicoil air seeder with a Steiger tractor that had open hyd system. We mounted a belt driven hyd motor to drive the fan. We put a flow valve on it to by pass part of the oil so we could regulate the speed. |
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WNW Illinois, Henry Co | Pat,
very good explanation,
Starting with the 81 year model IH 86 series, they are all PFC, closed center, as were Case tractors of same vintage.
i remember going to a sales meeting in 1980, intoducing them to the dealers, and they were bragging how good the system was, and oh yeah case also had it. then a few years later Case had IH too.
so most any, (Certainly not every) model had closed center since 1980 in the red series. dont know about any others except the JD ones as there were hardly any dealers of others around after the 80s
good luck
Edited by newag1 6/2/2017 14:23
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| I ran our JD vac planter for the first time this year with my 3545 MF tractor. Used to pull it with the 4450, and even the 4430 in the early years of the planters' life. Worked fine with the open center. Both JD's are closed center, but my MF is open. Oil temp is going to be higher with the open center. It's just a fact of physics. It's going be important to make sure to route the discharge the return flow directly to sump. If you just hook the discharge back to the service valve outlet, some of this extremely hot oil is going to be recycled back into the charge circuit. A fairly large portion is routed directly back to the intake side of the Hyd pump, without the benefit of cooling in the sump. Dumping 100% of return to sump at least ensures some cooling before starting over again. a open center in neutral makes very little pressure in the circuit. Very little heat, very little drag. When you pull the lever, ALL the oil in the circuit is forced down the work path, and if the work is less than what is being supplied, then the relief valve dumps the excess back to sump. Oil flowing over either the work, or the relief is going to make pressure (system rating) and this is where the heat comes from. Neat thing about the closed center, is that they only supply the exact amount of volume as what the work requires. No gobs of excess flowing over a relief valve making even more heat! Even on our 4430, we were told to dump the return directly to sump. My 8 row planter uses a tiny orbit motor, and the 4430 was able to keep up. Apparently, by the time the 50 series came about, it's ok to just use the service coupler for return. It had higher capacity pump. Closed center also relies on a certain amount of return to supply the intake side of the pump. Ever notice when you lift a single action cylinder dump wagon, how an early JD will chatter after lifting about halfway up? It needs time to recharge its internal reservoir.. and can continue after waiting just a couple seconds. It's 'starved' because a single action cylinder doesn't send return back to the intake side of the pump. |
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Fruita CO | The water system in your house is like a closed center system. Pressure is there all the time but no flow until a valve is opened. The irrigation ditch in front of my place is like an open center system...it runs all the time until I throw a dam in & open a headgate to divert water. |
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NW KS/ SC ID | wht one - 6/2/2017 11:09
Bill, I didn't know that, how do I adjust the flow rate on the White?
Bill is my dad, and That is an excellent question that hopefully Robert Greif or Kooiker know the answer too. :)
On the allis there is a little half turn valve with an indicator that comes through the cab floor on the 2wds and you can adjust it in the cab.
The White, all we have done is lower the system pressure with the screw under the cab so the pump doesnt have to work so hard.
After reading here on NAT, we became aware of a pressure relief valve, and I hope we were not adjusting it, as that would cause system overheat since its always in bypass.
Since all we seem to do with the White's is tillage (its what that big ol long frame does best! :) ) we like lowering the PSI so it will still lift the blade plow, but not much more. |
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NW KS/ SC ID | So they were PFC, not just PC? So that just left JD and White with PC and everyone else was running PFC?
Allis debuted PFC with the 7000 series in 73. Amazingly it works great. We never havy hyd. problems on our old allis', but the Whites seem to give fits. |
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ND | Everyone complains on JD that its all about their marketing but on the 1973 30 series you can adjust flow right on the remote & that has nothing to do with marketing people but Design People. Thinking the late 20 series had this design as well. The rabbit & theturtle flow lever. Really no other company had this remote valve but correct me if I'm wrong. |
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NW KS/ SC ID | allis had in cab control. a feature not found on JD till the 8000 series? :)
In all seriousness, it seemed to accomplish the same thing the JD flow rate control did, but it was done with a little arm in the cab under the seat. Allis only came standard with one control rod, but the others could easily be added. |
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Open Center/Closed center hydraulics questions
