hydraulic systems

[htiek126]

How do hydraulic systems without power beyond (closed center system) work? I am plumbing my 1510D for a FEL with a power beyond valve. I have since spotted a small inexpensive Bradco hoe for sale. It only has two hydraulic connection hoses, so I am expecting it is a closed center system. Can I plumb in some sort of relief valve upstream of the back hoe, or do I need to get an open center valve system for the hoe (very expensive!)?

Keith

 

[EdKing]

Just because the hoe only has 2 hoses doesn't mean its closed center. My backhoe has 2 hoses that connect to one of my SCVs, and it is open center. The control valves divert the oil to the cylinder that is operating, and when let go the oil flows through to the tractor. I am assuming that most if not all tractors operate with open center, so if the hoe is designed to operate on a tractor, it is open center.

 

[bruce1966us]

I agree, most 2 line systems are open center. Very simple to deal with. Every loader we install is open center.

Thanks,
Bruce
www.yanmartractors.com

 

[lens12]

An open center system uses a pump that pumps a constant volumn at a specified rpm. A closed center system varies the volumn according to the hydraulic demand. Most newer farm tractors use closed center systems. If you use a closed center valve on an open system the pump flow will be deadended & wreck the pump. If a open center valve is used on a closed system, the pump will pump at full capacity & the oil will overheat.
A valve with power beyond has 3 hoses . When the valve isn't being activated oil flows in the IN & out the PBY to another valve , such as the 3 point. When the valve is activated the oil goes through the valve to the application with the return from the application going out the OUT port to the hydraulic reservour. . A valve can be operated without the PBY fitting. The oil will go out the OUT to another application(may be back pressure, this is why PBY is used) or to the reservour

 

[bruce1966us]

Len just proved the point I was making. Open center is more simple.

Thanks,
Bruce

 

[htiek126]

I want to make sure I understand... You are saying that a two hose valve can have an open center system by combining the power beyond and out lines. The back pressure would then be caused by the use of a valve down stream and/or is the back pressure caused by a spool that is partially open?

 

[DFB]

Maybe these diagrams can help out. Both open and closed center systems are described and shown with and without power beyond.

http://www.bareco.com.au/files/hydraul/hydraul2001/hy17.htm

DFB

 

[roger_scotty]

Keith, you are doing the right thing in plumbing your 1510D for an open center with PB. Stay the course! A multiple spool valve with PB will give you all the options and is the simple, cheapest, and best way. Your can daisy chain other valves in series with the PB port on a PB-type valve. BTW, the backhoe will work with any system that provides hydraulic flow.
What Len is saying that there is a way to use a single set of non-PB spool valves - (some loader valves are that way) - in such a way that you can get an application to work without simultaneously providing for PB. But I think he is just explaining that for the sake of completeness because occassionally you will run across a tractor plumbed that way. That type of non-PB valve is perfectly suitable for one hydraulic application - like a loader. Nobody recommends that you do so by choice, because then you are limited and cannot use a second valve in the fluid line. If you try to put another valve in series in the fluid line you will get back pressure and weird effects. That is what happens sometimes when you hear of someone who has plumbed a tractor in such a way that when they raise the 3pt hitch the loader will move....things like that.

 

[lens12]

An open center & a closed center valve are 2 different valves. An open canter can be installed with PBY(3 hose) or without PBY.(2 hose). The technically correct way is 3 hose. It can be installed as 2 hose, but resistance from down stream valve may cause operating problems.

 

[roger_scotty]

This thread is educational in another way because as near as I can tell, all of us are saying the exact same thing but in different words.
In summary: open and closed center systems have completely different pumps and valves. The parts are not interchangeable. Most compact tractors are open center. Most implements don't care.
Only an open center valve with a Power Beyond port has the 2 vs 3 hose plumbing option. You can plug the PB port with a special plug and use 2 hoses only if nothing else is on the hydraulic circuit. Otherwise use 3 hoses, with the hose from the PB port powering the next valve in the series.

 

[htiek126]

To sum things up: If it is an open center valve with PB, then I plumb it in series. It is an open center valve without the PB option, then I should plumb the valve in series after the 3 point hitch (assumming the 3 point hitch does not have too much fluid resistance). If it is a closed center valve, then I need to find a new outlet section for a valve that was probably made in the eighties. But, it is an older Bradco hoe, so more then likely it is setup to be converted to an open center system. I have sent an email to Bradco with the model number, so hopefully I will have the facts within a few days.

Thank you for all your inputs.

Keith

 

[roger_scotty]

Some yes and some negative. Keith.
"If it is an open center valve with PB, then I plumb it in series." YES!

"If is an open center valve without the PB option, then I should plumb the valve in series after the 3 point hitch."
NEGATIVE. Get a valve with PB. The reason is 3pt "ghosting"; not resistance.

"If it is a closed center valve, then I need to find a new outlet section for a valve that was probably made in the eighties." NEGATIVE. You cannot use that valve.

"But, it is an older Bradco hoe, so more then likely it is setup to be converted to an open center system."

YES and No. Usually doesn't matter. Most implements themselves will work with either system. The changes are typically made in the output connections from the tractor; not at the hoe. Bradco might be the exception because they are made mostly for commercial equipment.So checking with Bradco makes sense. Bradco is one very nice commercial duty hoe - though somewhat heavy for a smaller compact.

 

[roger_scotty]

BTW, I went to the site at www.bareco.com and looked at the open center drawing that was mentioned earlier in this thread. It is only correct for one transitory moment...and that is being generous. Looking at the pictures, I think that the author may have just copied his closed center diagram and forgot to change it. Hmmm...the closed center one isn't quite right either. Best look elsewhere.

 

[htiek126]

Bryan at Bradco said that the hoe is normally shipped set up for an open center system. He said to pull the end plug on the valve. If the end plug is just a plug, then it is open center. If the end plug has a nipple, then it is closed center.

I question your second negative. If I buy a Prince SCV valve for example, the only difference in the three configurations of hydraulics are the outlet section of the SCV.

I am guessing that the nipple on the end plug blocks the open center through the work sections from reaching the outlet. Perhaps simply removing the material will change the configuration?

I do not understand when you say the attachments are the same, and it is the output connections of the tractor that are changed. Are there some tricks I do not know about? I would think it is strictly dependent on the attachment valve.

The hoe is a 3 point model 7LD, and it appears to weigh about 500 pounds. I will definitely put a frame mount on the hoe that ties into the sub frame mount for the loader. I just imported this 1510D a couple of weeks ago, and it is my first exposure to Yanmar tractors (including the other 7 tractors that the guys got). I was also concerned about the risks of buying sight unseen. I am absolutely thrilled with the condition, price, and design of the tractor (I have experience with a JD 855 with loader and hoe, and JD garden tractors), however, I plan to get a slightly larger Yanmar on the next order. Then, I think the loader and hoe will be just about right.

Keith

 

[EFC]

wow /w3tcompact/icons/laugh.gif, keith please email me before you do anything...Please! Buck@efcconstruction.com

 

[gbirky]

Keith,

I have a YM1510D that came from Japan with a loader. The loader has only 2 hydraulic lines between it and the tractor. The pressure (source) line is plumbed up to the hydraulic block that is mounted on top of the transmission casing. There is a plug threaded into the left side of this block. If you remove it and replace with a fitting, you can get hydraulic pressure from here. The return line just goes to the reservoir. Now unfortunately, I haven't been able to get the loader and 3pt hydraulics to work properly. It seems to me that something is amiss in the way the hoses are connected. However, it is also possible that Yanmar made the auxiliary hydraulics in some unusual way so that there is pby capability built into that hydraulic block, so that when the loader needs no flow, the flow is diverted.

To complicate things even more, I have a YM1301D that came from Japan with a loader also. It has the typical setup described in all these posts. That is, the 3 hose hookup. It works fine, but I have to move the 3pt lever to the fully up position to get flow to the loader. There is a pressure source, and return line hooked to the hydraulic block on top of the trans case. Then there is the low pressure return that goes into the trans case (reservoir).

Does anyone out there have experience with the YM1510D that could shed some light on how the auxiliary hydraulics is supposed to be used? It doen't have the two plugs that the YM1301D has, just the one.

Greg

 

[htiek126]

Greg,

On your 1510D there is a little "T" turn screw on top of the transfer case that turns the hydraulic flow out of the 3 point valve to either the 3 point hitch or to the outlet port that your loader is connected too. If you turn that all the way in, the loader valve should have pressure.

Keith

 

[htiek126]

Greg,

To be a little more correct, the "T" screw blocks the flow to the 3 point cylinder. So if you turn the screw all the way in, you block the flow to the 3 point hitch, which is also used as a safety to prevent the 3 point hitch from inadvertantly moving. I suspect that you will have flow to both the loader valve and the 3 point cylinder if the screw is turned all the way out, but only when the 3 point valve is opened. Then, the 3 point hitch would move up every time you wanted to run the loader, so you would need to screw that valve shut. Mine was locked up, and required some lubrication.

Keith

 

[pennwalk]

On a 186D there is a divider block on the high pressure line. It is on the side of the transmission. It has 2 ports for OUTLET and INLET. OUTLET is closer to the hydraulic pump and INLET is closer to 3pt lift cylinder. In order to use the divider block is is necessary to screw a headless pipe plug down in the inlet port which blocks an internal passage in the divider block. Without the plug the divider block is just a pipe and there is no reason for the fluid to flow to the auxiliary valve. The Auxiliary valve is rigged with PBY going to INLET, IN going to OUTLET and OUT dumps back into the side of the transmission. Thats how the operation manual shows it.

Chris

 

[htiek126]

Unfortunately, the 1510D is plumbed differently from the 186D. I have the 186D service manual and owner's manual, and I wish my 1510D had that divider block. Instead, I will be cutting and brazing the high pressure line. I guess it does not matter, because they put the pressure line and return line right in the way of the loader mounting holes.

Keith