Why no "Power Beyond" for Kubota tractor?

[Fallon]

I found this in the manual so it goes AGAINST all the bungee talk....


A Do not hold the lever in the "REARWARD" or "FORWARD" position once the remote cylinder has reached the end of the stroke, as this will cause oil to flow through the relief valve. Forcing oil through the relief valve for extended periods will overheat the oil.
A Whenusingthetractorhydraulicsystemtopowerfront loader, do not operate boom and bucket cylinders simultaneously.

Holding a valve open normally causes the pressure relief valve to kick in. That heats up oil very quickly & is a problem. If it's just going through the valve, through the backhoe valve then back to the tank it wont cause the relief valve to kick in. There wouldnt be any more restrictions using a bungeed valve than the backhoe being plumbed into the power beyond loop. Restrictions & overheating the oil are what the wording in the manual is trying to prevent.

 

[k0ua]

I found this in the manual so it goes AGAINST all the bungee talk....


A Do not hold the lever in the "REARWARD" or "FORWARD" position once the remote cylinder has reached the end of the stroke, as this will cause oil to flow through the relief valve. Forcing oil through the relief valve for extended periods will overheat the oil.
A Whenusingthetractorhydraulicsystemtopowerfront loader, do not operate boom and bucket cylinders simultaneously.

NO, no it doesn't, again you are confusing apples and oranges. OF COURSE you would not hold a remote valve open when it is looking into a cylinder as the cylinder would fill with fluid, pressure would increase until the relief valve opens. If the relief valve did not open, then your hydraulic pump would explode, or "grenade" as sometimes said. THIS IS NOT the same thing as using a remote valve to send fluid to a backhoe held open with a bungee cord which will when the backhoe valves are closed will just send the fluid back to the reservoir. Pressure does not build in this scenario as the fluid has some place to go. Thru the valve in the backhoe and then back into the reservoir or also called the "tank" which is the transmission of your tractor.

Lets start with the basics. Hydraulic pumps do not "make pressure" they "make flow". The hydraulic pump in your tractor is making a flow of hydraulic fluid, but when it comes out of the pump it does not have any appreciable pressure until it encounters something that resist the flow of fluid. The first thing it encounters on its journey back to the tank or reservoir is likely the FEL valve. Unless one of the valves on the loader is operated, the fluid just flows out of the valve thru the power beyond port.

Then next thing this stream of fluid encounters still flowing on its way back to the tank is the first of several remote valves. Again if the valves are not operated, the fluid flows on to the 3 point valve and then it dumps into the tank. The pump is constantly sucking fluid from the tank thru the suction filter and passing it out the "pressure" port to start this fluid journey all over again. I don't know the fluid flow specifications for your tractor, but you can look them up, but it will be many gallons per minute of fluid flow. BUT as long as no valves divert this fluid flow, there will be no appreciable pressure in the system. This is called an open center system. Fluid is flowing all the time thru all the valves in series but no appreciable pressure is developed.

This residual pressure will Usually be less than 100 lbs. And only because there is some resistance from all the hoses, valves and fittings. NOW, how does the cylinders do any work if this pressure in the system is at less than 100 lbs?

Here is how: As soon as you divert the fluid flow from this "normal" path from pump back to the tank then pressure builds rapidly in that circuit. Lets say you did operate that remote valve and divert flow into the bore of a cylinder extending the piston. The pressure builds rapidly in the cylinder and the piston starts to move, pushing any load the piston is attached to. This pressure can build to the point if the load does not move or the piston reaches the end of its stroke the pressure will build to the point that the relief valve on the pump will open. If for any reason this relief valve does not open, then the pump will explode or the engine will die trying to turn the pump or something will "give".

This is catastrophic failure. Of course normally the relief valve opens. But this is still a restriction in the oil flow and the relief valve is not meant to have the complete flow rate of the pump flowing over the relief valve for long periods of time as the oil will heat up. If you are a uneducated person you would continue to hold this remote valve open and allow the flow to continue in this manner and allow fluid to flow over the relief valve.

You would notice a "funny sound" and the engine will likely lug down just a little, as the oil continues to heat. This is why they caution about holding a valve open after the piston of a cylinder has reached the end of its stroke. As you have sense enough to let it go and it will snap back to neutral and allow the flow to continue on its original journey back to the tank. OF COURSE if it is a detented valve, then it WILL NOT snap back to neutral will it?

THIS IS WHY DETENTED VALVES ARE DANGEROUS FOR UNEDUCATED PERSONS. You might actually send fluid to a cylinder with a detented valve and when it reaches the end of its stroke just let it sit there with the relief valve screaming and the oil heating up. Or if you hold it back with a bungee cord it can do the same thing. OR if you send fluid to a remote that has nothing plugged into it, it will do the same thing. The fluid flow is looking into a "brick wall" in this case, there is no where for the fluid to go so the relief valve opens as long as that valve is held open either by a detent or a bungee cord or just by your uneducated hand.

Of course this is NOT the same thing as using a bungee cord to send fluid to the backhoe valves because the backhoe valves are going to send the fluid on to the tank. Preferably by dumping it into the fill port of the tank for the least amount of restriction. Remember fluid just flows on its merry way, many gallons per minute until it meets a restriction, then pressure develops when the fluid meets a restriction.

I hope this "book" helped some.

 

[k0ua]

Thank you sir - even more scared now than ever to even touch this thing.
I wante dto avoid the dealer as they are 50 miles away, but all this seems WAY WAY WAY over my head.

You and I are in agreement here. You have to have a basic understanding of how an open center hydraulic system works first, and then you could start this plumbing project. You do not have that basic understanding, I would highly suggest you take it to a competent dealer to have this job done. ALSO, there are plenty of mechanics that are incompetent and do not have a full understanding of these system either. As witnessed some of the cobbled up jobs people come back with. Lets hope your dealer and his mechanics are competent.

 

[LouNY]

So run the 2nd hose at the back of the tractor fill port by removing the quick disconnect - right?

Many times that is not the best return for your hydraulics,
splashing down and around to the fluid level can aerate your hydraulic fluid.

To the original poster you say your backhoe locks up with the hydraulics continuously applied.
Do you have both connections made on your rear remote valve?
When both lines are connected you should have established your open center flow loop,
fluid should be leaving your remote thru one connector, flowing thru your backhoe valve body,
and returning to your tractor thru the other connector on the same remote.
The only way I could see for it tobome "locked" and require reversing the flow would be if the backhoe was
setup with closed center valves or if a valve is locking into an operated position.
One other issue is possible if your backhoe valve body is set up with a power beyond and
that port is plumbed to your return line and the return port is plugged.

 

[Fallon]

You and I are in agreement here. You have to have a basic understanding of how an open center hydraulic system works first, and then you could start this plumbing project. You do not have that basic understanding, I would highly suggest you take it to a competent dealer to have this job done. ALSO, there are plenty of mechanics that are incompetent and do not have a full understanding of these system either. As witnessed some of the cobbled up jobs people come back with. Lets hope your dealer and his mechanics are competent.

I'll 2nd k0uas posts. Hydraulics arent rocket science, but do take time & energy to to properly research & understand. My first project adding 3 remotes & TnT to my L3200 took a while. Mostly me reading, learning, finding the limits of my ignorance then learning & pushing those limits further back. The challenge with hydraulics is it's easy to break expensive parts if you screw up. There is also a not insignificant danger of injury due to high pressure leaks. Do yourself a favor & take my word for it & dont Google for photos of hydraulic injection injuries.

Take your time & do the research here on TBN or elsewhere if you have moderate mechanical aptitude. Having a dealer or competent mechanic (who knows hydraulics, not all do) do the work is perfectly fine too. People only have so much time to learn various skills & work on assorted projects.

 

[Cat_Driver]

I copied your " book" to my hard drive ans will read and RE-READ until I understand the reams of valuable information.

When I first attemped this I did do as the Kubota dealer said and hand my wife ( HUMAN BUNGEE) hold the valve [OPEN] and the backhow would work then it would freeze up - I think you used the term Hit a brick wall. In order for it again to operate I would have her relese the valve and then engage again for it to come back to life.
Obviously I knew this was not correct.

I again called another dealer who said a DETENTED VALVE is the way to go at a cost of $1,400.00

So the two quick disconnects I have on the back of the tractor you're saying the one quick disconnect port is OPEN when the handle/valve is thrown forward BUT not fluid is going back to the tank as it is only going to the backhoe and not back to the tank. The brick wall method.

I can use the one side of the quickdisconnect to charge the backhow but I need the return from the backhoe to go into the "tank" of the tractor perhaps via a hydraulic T fitting.

What is happening is there is not fluid going back just going ONE WAY

 

[Cat_Driver]

You and I are in agreement here. You have to have a basic understanding of how an open center hydraulic system works first, and then you could start this plumbing project. You do not have that basic understanding, I would highly suggest you take it to a competent dealer to have this job done. ALSO, there are plenty of mechanics that are incompetent and do not have a full understanding of these system either. As witnessed some of the cobbled up jobs people come back with. Lets hope your dealer and his mechanics are competent.

"competent dealer " so far you guys are FAR FAR more competent than the two big dealers I spoke with.

One says use a bunger the next wants $1,400.00 to put on a Denent valve and says this "MIGHT" work?

You all here have been beyong gracious with your knowledge and are at least making me sound a little more intelegent when talking to these dealers.

I need to find a dealer that has the combined knowlege of you all here. HA

 

[Cat_Driver]

ROGER THAT

Funny how when you get three opinions on soomething that sounds plausable then as you keep digging you get 12 opions on how those opinions are rubbish.

With the help of all the kind souls here ( of course I need to now study the knowledge given till I understand it ) I am a lot better off than I was when this startd.

 

[Cat_Driver]

The backhoe was plumbed for a onboard tank and PTO pump, but they said "sure no problem connect it to your tractor"

 

[ericm979]

It sounds like it's not the Kubota BH.

I think Kubota makes a kit that would give you the BH connection. It should be a loop of hose at the back that is connected with male and female connectors. You disconnect it and connect to the male and female on the BH. That puts the BH in the loop. Like what you're doing with having your wife hold the valve open but without the valve and wife.

You can make the same without the kit, if it doesn't exist or is expensive. There should be a line from the remote valve body to the transmission. You'd replace that with a line that has the male and female connectors in it.

BTW I wonder if regen on the remote valve is causing your BH freezing up problem.

 

[k0ua]

I was going to write another book about how regeneration works and why you would maybe want it in a valve. But this guy explains if pretty well.
I haven't seen rear remotes or Selective Control Valves with regen, but I can see why you might want one. An example would be extending the batwings on a mower for instance, a low load but you might like the high speed. Many Kubota (and other brands) have regen on the loader valves. This is for a "fast dump" function to dump the load rapidly. The load actually helps the regen function. End result the worktime is reduced as you don't wait on a bucket to dump if you just used the normal speed of the pump flow to fill the cylinder. The additional flow from the rod side of the cylinder can be added to the cap side to push that piston out faster. Watch this video with diagrams to help out with understanding regen. When you are done you will have a much better understanding than a lot of mechanics.

 

[Cat_Driver]

It sounds like it's not the Kubota BH.

I think Kubota makes a kit that would give you the BH connection. It should be a loop of hose at the back that is connected with male and female connectors. You disconnect it and connect to the male and female on the BH. That puts the BH in the loop. Like what you're doing with having your wife hold the valve open but without the valve and wife.

You can make the same without the kit, if it doesn't exist or is expensive. There should be a line from the remote valve body to the transmission. You'd replace that with a line that has the male and female connectors in it.

BTW I wonder if regen on the remote valve is causing your BH freezing up problem.

I've come to the conclusion with everyones guidance that I ned to do as you and all other suggested get the fluid BACK to the transmission.

Now the problem is HOW. I have four ports used for two rear attachment quick disconnect. Two ports used for the loader. Two ports used for the grappler and the dealer locally doesn't seem to understand the concept of what you are all advising about the loop.

I may disconnect one of the rear quick disconnects and use that return back to the transmission OR somehoe make a T

 

[Cat_Driver]

You should still write the book. You way of explaining is amazing and helpful to the lay person.
You have so much knowledge it needs to be shared and you need to make a buck or two.

Even if you do a PDF book for download on Amazon for $2.99 it would be worth it.

 

[k0ua]

You should still write the book. You way of explaining is amazing and helpful to the lay person.
You have so much knowledge it needs to be shared and you need to make a buck or two.

Even if you do a PDF book for download on Amazon for $2.99 it would be worth it.

Thanks for the kind words. You should see me lecture on subjects I REALLY know something about, (electronics/radio/antennas). Most of my hydraulic knowledge is theoretical, not practical. I was a tech, then engineer with telecom companies, so electronics is more my forte.

 

[ericm979]

I've come to the conclusion with everyones guidance that I ned to do as you and all other suggested get the fluid BACK to the transmission.

Now the problem is HOW. I have four ports used for two rear attachment quick disconnect. Two ports used for the loader. Two ports used for the grappler and the dealer locally doesn't seem to understand the concept of what you are all advising about the loop.

I may disconnect one of the rear quick disconnects and use that return back to the transmission OR somehoe make a T

If you tee into two valves, neither will work as the flow will continue through the other side and won't build pressure in the cylinder you're trying to move. (unless you operate both at once, but that's not practical).

You can make your BH loop by replacing the line from the remote's valve body to the tank (transmission) with one that has male and female connectors. Keep them connected when the BH is off so the flow is the same, and connect them to the BH when its on. That puts the BH valves in the chain. If your remote valve body is bolted to the transmisison and it's output dumps directly into it, then you'd use the line from the loader valve to the remote valve body.

 

[Tractor Seabee]

Cat Driver,

I am still not seeing your whole picture. I posed some clarify questions you have not answered. Let's take the BH situation first. Do you have, or are contemplating getting the Kubota companion BH for your L? If not; are you using a third party frame mounted BH? If not that; are you thinking a 3 point mounted BH? Those are your only options. They may present different solutions depending on how they come equipt. Once you answer those questions we can get down to specifics of your installation. If you are getting the Kubota BH it should come with everything you need, make sure it does.

Believe me I am trying to help, not harass. Since getting my BX I have done a lot of research into hydraulic systems. Do you have the WSM for your L? If not get one, it is essential for what you are contemplating. Around $100, and have to order from a dealer.

Ron

 

[lilranch2001]

James has given many helpful tips over his 10 years on TBN, and is always a gentleman

 

[Michael In Tennessee]

It sounds like you are getting some useful information. I'll add my own and hopefully, it helps rather than confuse.

Your Kubota L4060 is quite similar to my MX4800. It is important to have Kubota unique information and not just generic info.

On your L4060, your rear remotes are fed from a port on the side of your 3 pt cylinder under your seat with hard lines that are custom built for your model tractor and are not very useful for a backhoe. Using the rear remote is an unnecessary burden for powering a backhoe as well.

So, lets completely ignore the rear remotes for this issue.

What you want to do is to mimic the way Kubota powers the OEM backhoe. As has been previously mentioned, they install the backhoe with a loop of hose from the PB port of the FEL to the back of the tractor, returning the fluid to the hydraulic block under the floorboard on the right side of the tractor. This takes two hoses and a male/female quick disconnect pair. The hose from the FEL power beyond port to the rear is about 8 ft long and the return is about 6 ft long. Use some garden hose or such to snake through the tractor frame and measure out for your specific tractor. Use the same diameter hose, with the same type of ends, as currently used from the FEL PB port to the manifold block. (My MX is 1/2" with JIC flare fittings.)

Since the picture you posted of your aftermarket Backhoe hose diagram does not show a tank line, then it hooks up just like a OEM backhoe and two lines are all that is needed. You do not need a tank line.

At the FEL valve, the power beyond connection should be the most outboard hose that is not a hose going forward to the FEL. It should go from the FEL valve to the block under the right floorboard. That hose gets removed and replaced with a long hose to the rear of the tractor terminating with a QD. Then, The mating QD and a hose come back forward to the hydraulic block under the floorboard.

Now, if you do what I said in the previous paragraph, you will see that all you have effectively done is created a really long output hose from the FEL. Logically, no hydraulic re-routing has been done, but you now have power beyond capability at the rear of the tractor.

Then, you add mating connectors to your backhoe, connect it up and your done.

NEVER, EVER start the tractor without the backhoe connected or the two rear hoses connected. The flow loop must always be functional.

This also works on your trencher IF your trencher has its own control valves and does not have a provision for a tank line. If you need control valves for your trencher, then a different conversation has to occur around that specific tool.

 

[ericm979]

Doesn't Kubota make a kit for this? Perhaps the dealer's not understanding what it is that you want.

When I go on Kubota's build tool and add a backhoe to a 4060 it adds two packages, one of which sounds line a mount. The other ($300 something) might be the hydraulic connection.

 

[Tractor Seabee]

I think we all need to sit back and get back down to basics. Poor Cat is probably so overwhelmed with information on a subject he does not understand to begin with, that he cannot think straight. I am probably as guilty as anybody with providing information that does not bear on his basic problem. With long discourses he probably gets lost in the first couple sentences.

As I have asked twice now and he as never provided an answer to the basic question: What BH are you trying to connect; Kubota companion to his L, some brand after market frame mount, or 3 point hitch unit. That probably creates 3 different solutions. One of his posts has a BH piping diagram that could allude to an after market BH. From what I know about Kubota all their BHs have a return to tank (T) line from its valve stack.

Once he answers that question, we can probably provide a direct to that unit definitive answer. Pictures and diagrams always help more than words as long as they deal with his specific brands and models.

Ron