O/T Do I need closed center hydraulics

My current tractors have closed center hydraulics, I am looking at a newer tractor with a loader and open center hydraulics.

My hay baler (NH664) has its own hyd. cylinders as does the bush hog, everything else uses a cylinder that I remove and install on implements when I use them and it just raises and lowers, i.e. plow, disc, corn planter, corn picker etc....

I understand the difference between the two types, but having never used an open center machine, I don't know if it will effect the operation of my implements or not.

My question is this, Will I be able to tell the difference between my old loader tractor with the closed center and the newer one with open center?

Is there any reason down the line I will be sorry I bought a tractor with open center hydraulics?

Thanks for any help

In my experience, there is no noticeable difference in operation. Closed-center hydraulics tend to be more complicated and more expensive to work on, that's all. They also tend to create starting problems, burnt up starter motors, etc. Pumps tend to be proprietary instead of generic and cost more, etc.

I was a Deere mechanic for many years. Deere's claim to fame with their closed center systems was a faster response since 2200 PSI oil was instantly available all the time. With an open center system, there is zero pressure until you put a demand on the pump. With a closed center system, full pressure in sustained, all the time, up to the hydraulic control valve.

I've got five backhoes and several crawler-loaders. Most have open center systems, but I've got two with closed center. There is no real difference in cycle times, response rate, etc.

Many modern pieces of equipment have convertible control valves that will work with closed center or open center - just by changing one large plug.

One advantage with closed center is - it's easier to plumb in extra hydraulic control valves without worrying about extra flow dividers or priority valves. All can be hooked in parallel, whereas an open center system needs all hooked in series unless there's a flow divider involved.

Since the open center system is contantly flowing oil, there will be more heat in the hydraulic system and take more power from the engine. All manufacutors have gone away from closed center systems so their advantages probably do not outweigh their complexity.

If for some reason you are running a hydraulic reset plow, that was designed for closed center hydraulics, you will have trouble with an open center system.

jdemaris is correct. The definition of open center is that when the valve is in center position, oil drains back to the reservoir, thus less pressure is exerted by the pump. In a closed center system, oil flow is stopped by the valve in center position, thus causing the pump to have to pressurize non-flowing oil. There should be no difference in actual applications, however I believe the open-center hydraulic levers are easier to move than the closed center ones.

Today's tractor hydraulic systems actually have both open center and closed center hydraulic systems within the main system. I don't think today's tractors are entirely closed center or open center.

Mathias NY, not exactly correct. In a closed center system, the pump is ALWAYS pressurizing the fluid to a high PSI, and maintains that by using a high-pressure bypass valve. So you are still pumping the fluid, whether it's an open or closed center system. Since the closed center system is running at MAX pressure when not being used, it is the one that generates more heat and is less efficient. An open center system always circulates the fluid, but when the valves are centered it is at a very low pressure, and therefore doesn't generate as much heat or use as much fuel

Usually - it usually works just the opposite from what you stated. Overheated hydraulics was - and still is - a big problem with closed center systems. Not with open center.

Open center system constantly pushes oil at near zero pressure. The only exception is when a filter is partially plugged causing a flow-restriction. There is very little heat caused by flowing zero-pressure oil. If it's run through an open-air cooler - the flow helps to keep the oil cool, if anything.

A closed center system must work to maintain a very high line pressure - usually 2250 PSI. Even has to do it when cranking the engine to start it - thus the many starting problems and burnt starter motors on John Deere tractors. In theory - when everything is perfect in the tractor - the pump is supposed to reach the high pressure setting and shut itself off. In the real world, that rarely happens. Small internal leaks develop all over the tractor. They don't affect operation - except it can make a hot tractor very hard to start - and causes hydrualic system overheating after long use. In addition, since there is no real flow of oil when functions are not in use, oil coolers don't work very well. With Deere, two systems are used together. An open center gear pump feeds oil to the main closed center piston pump. Feed oil gets some cooling, but rarely enough.

The pump for a closed center system is usually of a different design than that of a open center system. Its built to deal with the "dead head" constant pressure. The open center pump will heat up and fail in time if continuosly operated in a closed system.

Both open center and closed center systems are available today. The newest closed centers use a variable displacement pump so they aren't using power when no flow is need.

Those pumps are $$$ and the controls to run the system are complicated.

The benefit is if you need low flow when running high rpm's, you can set a flow control to exactly what you need. The main use of this I know of is sprayers if you are adjusting pump delivery volume to a set value and also for folding their spindly booms slowly without breaking them.

Old fashioned closed centers are one of the big reasons many Deeres used so much fuel compared to others.

You posted: "The newest closed centers use a variable displacement pump so they aren't using power when no flow is need."

WHAT do you think DEERE always used, from the first 4010? Why, a "variable displacment pump", of course! Once again, nothing new under the sun!

You posted: "Old fashioned closed centers are one of the big reasons many Deeres used so much fuel compared to others."

That's a bunch of BULL, as well. Those old DEERE systems, when operating normally, go "out of stroke" when there's no hydraulic function oil needed, just like the newer systems do.

There is very little heating of the oil in a properly-functioning Deere closed-center system when in "standby". Open center systems take power and make heat, as well, while continuously pumping oil.

I won't argue about the fuel consumption, but I'm sure it had a lot more to do with the older ENGINE designs than their closed-center hydraulic systems.

All the external plumbing and cylinders will work exactly the same with open and closed center hydraulics on the tractors. Go use them.

Gerald J.

And now everyone has gone "Load Sense" It is the best of both world. No flow, low pressure in stand by position The Older Deere pump is either no pumping stroke or full pumping stroke. Those piston either contact the cam or they don't. I got a 20 minute lecture one time on the idea behind it by one of the engineers that was in on the design of it back in he late 50's.

I guess I should have been clearer...

When I referred to closed center system, I should have added that also means pressure-compensated. We have hydraulic presses where I work and I have done tests with the various pumps. A 10gpm pump pulls more amps when it is at full flow (no load) than when it is full pressure (no load). Since no work is being performed in either situation, the energy is essentially converted to heat. The situation that uses less energy produces less heat.

An open center 10gpm pump is moving (up to) 1.3 pints of fluid per second the entire time the tractor is running. A closed center system moves none unless flow is needed.

My theory on the burnt starter motors is that Deere may have used bigger pumps that their competetors. A bigger pump is no extra power, when not in use. However if the system has leaks or controls are adjusted when the pump is off, the starter will have that much more work to do.

Most tractors with closed center systems have to use two pumps instead of one. Closed center pumps cannot feed themselves with oil and thusly require gear pumps to feed them. Deere usually feeds the front piston pumps with gear driven, 7 GPM open center pumps.

With Deere and the burnt starters - no theories are needed. It's a proven fact with what causes burnt starters and hard cranking. Internal closed-center leaks which just about always exist in tractors. I've been working on them since they were first introduced by Deere and we had plenty of problems with them, even when brand new.

In regard to electrically driven gear pumps hooked to conventional pressure relief valves (like most open center tractors use). If you hook power to a pump for a half hour with free flow, zero pressure, and then hook for half an hour with blocked flow and the relief valve cracking - MUCH more amperage is used with the system blocked. If you doubt it - go hook a very large, or shunt-wired amp-meter to a Western or Meyers snowplow pump and try it.

I've seen several open center pumps hooked to closed center systems. They usually last about one second and blow to pieces.

The "on" or "off" function only exists with a perfect pump and system. In the real world with used tractors, it just about never happens that way.

I too was subject to a lot of indoctrinization from Deere reps about the greats attributes of their closed center systems. Also had to attend many service schools. The reality is, we lost many customers because of problems with it. Especially with C series backhoes.

I never saw any evidence of Deere tractors using excess fuel due to closed center pumps. Deere tractors with PowerShift transmissions did cause some loss. One example, to make a fair comparison - here are two Deere tractors that are almost identical except one has an open center pump and the other closed center. Same engines, same basic tractors. The closed center tractor actually tested with better efficiency, not worse.

Deere 820 with 152 diesel - best fuel - 14.2 horsepower hours per gallon. Open center pump.

Deere 1010 with 152 diesel - best fuel - 15.4 horsepower hours per gallon. Closed center pump.

That is not the way the closed center system pumps work. When they go out of stroke, they are out of stroke. Pistons do not move, so they are not pumping against pressure.

Obviously I'm out of my league when it comes to expereince. The point I was trying to make is that a properly functioning closed center hydraulic system uses less power than a similar open center system. Your comparison of an 820 to a 1010 seems to illustrate that.

Bout the time I think I understand something, I get confused again.

So what is my IH 2606, closed or open center? Seems to me it is closed center.

A variable displacement pump can be used on open center hydraulics but I think has to be used on closed center hydraulics. I have a variable piston pump on my open center Cat because it is better for the quick attach backhoe. The variable pump allows for faster cycling without load and more power under load. Basically a simple load sensing system although there are more complex ones. Hydrostatic transmissions can have all different kinds of configurations. A hydraulic cylinder after the control valve doesn't care how the oil gets to it. It will work either way but more efficiently with some systems than others. Dave

I can't say for sure, but between the 820 and 1020, I suspect those small efficiency differences have nothing to do with the hydraulic systems. Probably more to do with the individual tractors - and the slight difference in injection pump and timing specs. You can take identical tractors brand new - put them on a dyno and get slightly different readings. I suspect the same is true with "fuel mileage" measured in horsepower hours per gallon.

Open Center and Closed Center, in my opinion or tow nearly useless terms when it comes to describing the hydraulic systems on modern tractors.
Reason being, nearly none are truly an open center system and none are truly a closed center system... so it would depend on what tractor you're looking at.

I'm not really familiar with the plumbing on the newer Deere's that claim to be open center, but I'd suspect that it would range anywhere from tandem center to a fixed displacement load sensing type..
Ford used gear pumps in a fixed displacement system, using closed center load sensing valves AND an unloading valve to unload the pump(s)... so they technically class that system as 'open center' because it's fixed displacement. NH used that right up to the end of the TS series on the basic spec tractors.

What you commonly find on high spec tractors today is a CCLS system (Closed Center Load Sensing) which is a variable displacement system with the exact same spool valve that Ford used which sense load. They're also known as PFC (Pressure Flow Compensated) hydraulics. The main difference between PFC and the old Deere closed Center system is that the Deere must go to high stand-by to destroke the pump. The PFC system is normally destroked (low stand-by) until it senses load. When load is sensed it strokes the pump sufficiently to maintain the pressure differential in the pressure/flow compensator valve so it's never pujmping more than is needed at ANY MORE pressure than is needed. The old Deere system simply sensed a leak when you opened a valve and the pump would stroke fully with the goal of overcoming the leak... which is why they're not so well regarded in some circles. They do develop leaks over time, which can be hard to find... and cost money to fix. Not fixing them leads to overheating of the oil. PFC systems are supposed to be less prone to such problems since they're not under pressure constantly.

With all that said, personally, if i was buying a new tractor today I'd be going to a CCLS/PFC system. I have some need of it on a Deere harvester with it's on CC valve bank... and yo neve know what you might buy down the road. It won't hurt you to have a higher end system then you need today, however... for what work you list, the 'open center' system will work just fine.
I'd also suspect that from a fuel efficiency standpoint the open center system will generally be more efficient. The CCLS system has all the parts of the open center system that draw power, plus the variable displacement pump which draws more power to turn... so for basic use the OC system is mroe efficient. For heavy use with multiple circuits and less than full system demand the CCLS system will be more efficient because it doesn't need to dump oil to sump at pressure the way that the OC system does.
Confused yet?


Rod

I'm not confused - but do get a little disgusted with the overcomplication that exists in newer equipment. For my purposes, and many others, it's hard to beat simplicity. I'll take an open center tractor with a gear pump and many generic parts anytime than some rig with proprietary and expensive parts.

In regard to the terms "open center" and "closed center" - in general, they refer to the type of hydraulic function control valve used - regardless if on a tractor, a press, log splitter, steering system, etc. If the valve when in neutral lets all oil pass - then it has an open center. If it blocks all flow of oil, then it is a closed center. It's as simple as that. But, many tractors and other machines are, more-or-less hybrids with no proper or discrete label.

Ok, now I think mine is open center because it bypasses when the valve is in neutral.

So does that mean when no hydraulic valves are being operated that it is pumping straight through to the return sump under very little pressure?

I kinda had this idea that the system always circulates all the time at the same pressure as the check valve limit but if I understand it right, as of now, then the only time the system goes to the max psi of the check valve is when a hyd valve is opened to operate something. Correct?

What bothers me with the newer stuff is the degree to which they're integrated electronics into the hydraulics systems.
I don't see that PFC systems are necessarly complicated in their basic form... but they've gotten to the point where the electronics are deep into the flow controls, etc. I think that adds up to a lot of little problems that cost a lot of money.
Where I've spent my time on Ford's I find that just about everything is proprietary, and all modestly expensive... and those are open center systems with Rexroth load sensing valves. That's not cheap.
I must admit though that I've become fairly fond of the Deere electro-hydraulics harvester controls. That could work with open center, but even those systems are complicated...

Rod

Which means that 50 years from now this site won't do any good when someone posts to ask about fixing their 50 year old tractor. Its getting too complicated to fix. I used to overhaul cars back in the day but not now.

... but that's the price we pay. I don't, and couldn't use 50 year old tractors for anything today. They're just heavy conversation pieces here. I leterally couldn't put 10 hours a year on our Ford 860 unless I started it and left it idle.
It's just too inefficient to use for modern work.
I'd expect that the tractors of today will suffer the same fate in 50 years if not a lot sooner. Obsolete...
That's the main reason to go with a higher end system today. You stave that off a few more years and hopefully get a bunch more use from the tractor before it becomes impractical.

Rod

HTR
That is an incorrect statement. They maintain pressure but no flow. The pressure will be lower however if it has load sensing also.

jdemaris
Closed center pumps can feed themselves. A charge pump is not always needed. None of my tractors use the charge pump.
Some leakage is required in a pressure compensated (closed center) in order to keep the controls from hydro locking.

There is no such thing as a standard "closed center" pump. There are many variations. Any pump can be closed center if there is a way to shut it off when a function is not being used.

Piston pumps in general cannot feed themselves with oil, i.e. no suction. Even hydrostatic pumps use extra charge pumps.

In regard to the pump you are talking about? Kind of hard to comment since you don't give any specifics.

All John Deere closed-center piston pumps require addtional charge pumps to keep them supplied with oil - they cannot draw oil on their own. Same goes for many Massey Ferguson systems.

Again, as to your tractors? I have no idea what you have.

I know of several sucessful farms that use mostly tractors from the 60s and 70s. I can see in a large grain farming area where the most modern tech might be needed. But here in our dairy farming area, the most cost effective farms that I know of personally, use older tractors. The truth is - there are many tractors from the 1960s and 1970s that run just as efficiently as the newest tractors at certain power levels. And, the older tractors are much easier and cheaper to work on. Keeping older tractors makes it easier to have many tractors that can ge properly sized for the work they do. You mentioned your 860 Ford. Well, when used to work at 20 horsepower, that 860 will run more efficiently than the newest, most efficient turbo diesel tractor is it's over 80 horse.

My neighbor, who just retired debt-free from dairly farming used a Deere 2520 and 4020 along with a few two cylinder tractors from the 50s (a 630 and 520). He is one of the few farmers I know that was always dept free and had a very high herd average for milk production. He did, however, buy a new Deere combine to do fall custom work for other farmers.

Another neighbor still dairly farming has two Deere 4020s, one 3020, an Allis Chalmers ED-40, a Deere B for raking hay only, and a Deutz-Allis 140 horse 4WD. He is also debt free.

Another neighbor who grows/raises certified organic beef and vegetables uses 1970 IH/Farmals only and does fine.

We've got around 10 large farms left in my general area. The one doing the worst and about ready to go under has all modern equipment and a huge debt load.

On a side note, industrial dirt moving equipment is a different story. If you get caught with a old leaker, you can be in big trouble fast.

Actually, our 860 sat rusting because it was more efficient to use the 7710 than it was to use the 860. I don't disagree with your statement generally, but that tractor is not efficient in any league. I do generally use the smallest tractor I can get away with, but that tends to be a good deal more than the 860. We just got to the point where it wasn't practical to sit on a 40 hp tractor for days when the 80-100 hp will do the work in a fraction of the time.
Your friend using a 4020 isn't really an example of what I'd consider using irrelevant tractors. With the exception of it being 2 wheel drive it'll do anything that most modern tractors will. It's also an example of having a high end hydraulic system. That tractor pumps what, 20 gpm or 24 gpm? Extremly high for it's day and able to handle anythign in it's class yet. Had you bought a low spec tractor in it's day you'd get about 7 gpm, utterly, totally useless in a good many 80 horse tractors today.

I'd also be curious to know what happened to your firend's land since he retired? Was it cut into lots or rented out?
Reason I ask is because anyone who followed that scheme around here certainly got by with what they had, didn't owe money, made some money, probably maintained their old gear quite well etc... but they fully depreciated and decapitalized their business doing it. The options that exist for someone wanting to buy that operation or keep in running in the family are one of two things: go to their ears in debt and hope it works or walk away because they can't afford but it and make th epayments let alone upgrade it.
It works fine for the guy running the thing down, but when he expects someone to buy it from him and make a living, the numbers never work... which pushes someone to expand, debt, debt and more debt.
That's just how it works. We've lost 20% of our dairy producer numbers in the past 5 years and we lost 20% of that in the 5 years before that... and probably so on for the 5 years before that.
The main reason is that many of these farms were operated exactly as you describe and nobody can afford to buy the farms as operating units for the price they will fetch if broken up... so the cows go to the auction, the quota goes on the exchange, the equipment is sold at auction and the barns sit empty.
The land may sit idle, get rented out to someone else or get sold for building lots depending on where it's at.
The farms that continue on are farms that were continously upgraded with new equipment, new barns, ever expanding and many are heavily in debt. There are very few exceptions to that rule. Some do fail, but most keep going.

Rod

I'm not a Ford fan, although I own a 641 (for bush hogging) and a 4000 industrial with a backhoe/loader. My 4000 has the 172 gas, and the 641 has the 134 gas. Good engines - but can't say much good about the tractors. The 641 is too short, too light, too fast in 1st gear, lacks live power, etc. That's pretty bad considering it's a 1960 tractor. I've got a Deere 300 utilty tractor in the same power range that is twice the tractor the Ford 641 is.

My point was about the more usuable older tractors, e.g. Deere 1020 (or 300) 2020, 2520, 3020, 4020, 4320, etc. And of course, the many others of different makes.

The Ford 860 gas engine can make 40 PTO horsepower all day long with a fuel efficiency rating of 11.8 horsepower hours per gallon of gas. That is exceptional for a gas engine.

Now, take a 40s John Deere B two cylinder - that so many rave about in fuel efficiency. At 27.5 horse max power it scores an 11.5 HHG. The Ford beats it.

Now, take a modern Deere turbo-diesel 6215 with a 276 cube engine. At 80 horse it runs at 15.9 HHG. But at 33 horse it drops to 9.7 HHG. At a 17 horse load it drops way down to 6.4 HHG which is pretty dismal.

An AGCO-Allis 8745 with a turbo-diesel 239 cube Cummins? 75 horse at 16.2 HHG. At 46 horse it drops to 12.3 HHG, and at 31 horse it drops to 10 HHG.

With the price of fuel right now, the Ford 860 makes cheaper PTO power at 40 horse on gasoline, then the modern AGCO-Allis or Deere turbo-diesels do on diesel.

My one neighbor was the laugh of the farming community when he bought a brand new ED-40 Allis Chalmers back in the 60s. He bought it mainly just to run his silo blower and did so since it used much less fuel then his Deere 4020 did on that job. He got picked on, at that time, mainly because the Allis ED-40 was "foreign" being a British tractor. "ED" stands for English Diesel.

In regard to the fate of farms here. Amish are moving in all over and buying up farms. But, they only do so when there are many farms contiguous to each other. They won't buy a farm that stands alone with no others near by.

I've got two long-time dairy farmer friends who retired recently. Both have different stories.

Farmer #1 - was raised on a family farm. His dad went broke (spend more time in the bar then the barn), so he took the farm over and did much better. He is a very good business man, musician, and farmer. Also good at using and maintaining old equipment. He raised a family, did his own farm work, played guitar in a country band, did custom farm work for others - and continuously invested in real estate out in California and in Florida. His farm was always debt free, but he often bought houses, rented them, and let them pay themselves off from rent money (more-or-less). His biggest tractor was a Deere 2520. My Ford 4000 backhoe came from his farm. When he gave up farming - he sold off - 30 acres, barn, and farmhouse to city people (non farmers). He then sold his best bottom land to another farmer who is very heavy in debt right now and trying to find a way out of farming. He still owns a couple of hundred acres of highlands - 1/2 fields and 1/2 hardwoods. Woods gets selectively logged every 10 years - and last year yielded him $30,000. The fields are leased - to the aforementioned large farmer and the lease pays the taxes. He comes here from Florida and spends the summer here with his wife, camping on his farmland. Years back, he swore he'd never sell it until he could get $1000 per acre for it. It's some of the most beautiful land in town with amazing mountain and valley veiws. Well, he's been offered $4000 per acre recently, and hasn't sold yet. But, I think he's getting close. He still does small-scale custom farm work in Florida with a 40 horse Kubota tractor. Up here, he has a Deere 300 that I found for him. When his land sells, it will not be farmed, I'm sure.

The other guy - farmer #2. A confirmed bachelor. No kids, no phone, no TV. Never had health insurance either. I did most of his repair work, and he let me cut all the wood I wanted and tap his maple trees to make syrup. He was heavy into the barter-system. One year he got a hernia and almost had to give up farming. He had to go to Canada to get an operation. In Canada, the job was 1/2 price to cash payers. Farmed with a Allis ED-40, Deere 3020, two 4020s, and an AGCO-Allis 140 horse 4WD with a Deutz. He hated that tractor from the day he bought it. Also had gorgeous land, but a crappy old barn ready to fall down. Over the years he had many offers from investors to buy the land - but he always refused. He had a nephew that he always hoped would take over the farm. Didn't happen. His nephew bought a farm further up north instead. So he held out until he found someone that promised to farm the land. He sold the farm for 1/2 it's value with a small down payment and held a mortgage. Long story short, he basically got jerked around. The local guy sold off the farm in pieces. But . . . 1/2 went to yet another farmer at over $4000 per acre (that's high for here) - and - the other 1/2 was bought by a logger who is tryng to become a dairy farmer. So, we'll see what happens.

If I had to guess, I think in less then 10 years, all the farms here will be gone. 30 years ago, we had over 50 dairly farms just in my small town. Now, I think there are three.

I will mention a guy down the road from me operates a farm with all new equipment and keeps buying land. But . . . he also has a good job with the State, and his wife has a good job as a teacher. He recently suspended his dairy operation so he can put in more time at work. He's near retirement age, so if he puts in more work hours, he retirement benefits go up. His plan is . . . to buy a new herd and start milking again in a few years once he retires from his State job. At present, he leases the farm out, raises heifers, and does the crop work for the people leasing his farm. Not exactly what you might call "old fashioned" farming. He seems to do well though - as far as I can tell.

I'm just going by what the tractor burned. The 860 we have, poorly tuned or otherwise, fo ras long as me or my old man cna remember would burn 2-2.5 IGPH which is right about what the 7710 would burn on nuisance work.
In our situation where we had to lug pump gas in cans as opposed to dyed diesel from an on farm tank... it was a pretty simple decision.
I did grow up on the seat of the 860 and put a lot of hours on that tractor learning to drive, and we did get a fair bit of light work from it many years ago, but man, it liked gas.

Sounds like ag has gone about the same direction in NY as it has here. Quite sad really.
I can remember when I started farming (2000) we had over 400 milk shippers in NS. We had 259 as of the end of August, and looking like 1 more gone last week... There's going to be a lot more beef and hort guys go this year I think. Not good.

Rod

I have a John Deere 2030 from somewhere in the 1970's. My 'hydraulic' question relates to hooking up a Stanley HD45 rock drill (this is east TN, you can't find a flat spot to park your car without having to blast) to the tractor's hydraulic ports - which I have never used so far. The literature on the drill says it is for open-center systems, and if the 2030 isn't of that configuration I am having difficulty figuring out how that would impact (pun intended) the drill. What problem(s) would result?