BH77 Hydraulic Concerns

[Henro]

Dan, you seem to have ignored my questions, but maybe did answer them, indirectly.

So if the 3PH is properly designed, at the top of the stroke system flow is diverted and there is no pressure build up on the incoming line? Not sure how this is accomplished. So somehow the control of the piston is eliminated, and position is locked, and hydraulic flow proceeds wherever the circuit take it?

This would mean that the operator does not have to do anything to disable the 3PH as far as dead heading the hydraulic circuit goes.

Assuming that the 3PH does in fact pass fluid regardless of position, and regardless if it is in the top most position, then my second question is answered, as if the grapple would be put before the backhoe control valve assembly, the T port would not see a high pressure, regardless of how the 3PH was operated. Is this correct?

The third question, as to why you show the 3PH in your drawing when it has no affect regarding the increase of T port pressure, must be simply because it is there in the circuit and should be shown.

So how did I do? Did I answer most of my questions correctly?

Still cannot see what may be obvious, that is, how does the 3PH control, when in the upmost position, when the control lever is not released, prevent pressure in the circuit before it from rising pretty high? With position control this seams likely, for reasons I can imagine but do not know. But what if position control is not a feature of the tractor?

 

[TheOldHokie]

Dan, you seem to have ignored my questions, but maybe did answer them, indirectly.

So if the 3PH is properly designed, at the top of the stroke system flow is diverted and there is no pressure build up on the incoming line? Not sure how this is accomplished. So somehow the control of the piston is eliminated, and position is locked, and hydraulic flow proceeds wherever the circuit take it?

This would mean that the operator does not have to do anything to disable the 3PH as far as dead heading the hydraulic circuit goes.

Assuming that the 3PH does in fact pass fluid regardless of position, and regardless if it is in the top most position, then my second question is answered, as if the grapple would be put before the backhoe control valve assembly, the T port would not see a high pressure, regardless of how the 3PH was operated. Is this correct?

The third question, as to why you show the 3PH in your drawing when it has no affect regarding the increase of T port pressure, must be simply because it is there in the circuit and should be shown.

So how did I do? Did I answer most of my questions correctly?

Still cannot see what may be obvious, that is, how does the 3PH control, when in the upmost position, when the control lever is not released, prevent pressure in the circuit before it from rising pretty high? With position control this seams likely, for reasons I can imagine but do not know. But what if position control is not a feature of the tractor?

I was not ignoring you - my responses were intended to cover questions coming from multiple people including you. So as regards this set of questions:

1. The diagram represents the OPs system as plumbed by the dealer . That is what started this thread. so iIf its in the system its on the diagram. Simple Eh?
2. It seems you are stuck on the operation of the 3pt valve. I thought I covered that pretty clearly in a previous post. In the simplest terms its a closed loop feedback system. Even systems without position control (like my 1941 9N) shut of at the end of stroke so as to avoid dead heading the pump. In that tractor its simply a mechanical trip that nudges the spool back to neutral. The mechanisms vary greatly with the design of the 3pt valve but the operation does not. Consult the workshop manual; for a description of how that works on your particular tractor. The workshop manual for my B7200 goes into great and gory detail on how it works. The 9N/8N manual is a bit more terse. As I said earlier - on the L3901 the operator can defeat the position control shutoff by holding the lever in the full up position BUT the guide plate for the lever limits the travel of the lever making that impossible as long as the plate and stop are in place.
3. There may be tractors out there with a 3pt that does not behave this way but I have never seen one. If you have one please share the details with me - I always like to learn new things.

Dan

 

[minthral]

The grapple is not feeding the backhoe. That is the problem.

There is no need for a tank port to be rated at full system pressure.

I will draw you a schematic. High pressure in red, low pressure in blue. Both the backhoe and grapple are using the tank port for high pressure carryover. The grapple valve is rated for that - the backhoe valve is not. Move the grapple ahead of the backhoe and everything is OK because when the backhoe is mounted the 3pt is disabled.

Dan

View attachment 71685

I have an L3301 and I checked how dealer did mine. I think it looks similar to this. At first glance, it's really confusing as I was expecting grapple/third function to be close to loader, but it's coming from the back. I got 2 remotes, and they're definitely first. 3point is 'locked in lower position' with the backhoe installed and dealer said don't touch it.

My third function isn't 1/4 inch hose... its like 1/2+... it's bigger than loader hoses.

My BH77 works great. Rapid movement unless I'm trying 3+ functions at once...you can do it, but it's more controllable and faster to only do 2 max...as soon as you try 3+, it significantly slows down.

Reason I found this post is one of my third function couplers (male) has tiny leak that starts when fluid is hot. Also a tiny leak around third function valve hoses. Land pride kit.

 

[Henro]

There may be tractors out there with a 3pt that does not behave this way but I have never seen one. If you have one please share the details with me - I always like to learn new things.

Dan

Sorry that you seem to have taken offense to my honest questions, trying to learn something at my end.

You are always very helpful to others.

If I offended you by trying to improve my knowledge of how things work, that is the way things go. BUT I was sincere in what I asked...

 

[TheOldHokie]

Sorry that you seem to have taken offense to my honest questions, trying to learn something at my end.

You are always very helpful to others.

If I offended you by trying to improve my knowledge of how things work, that is the way things go. BUT I was sincere in what I asked...

Henro I took no offense. I was simply trying to politely answer your question.

Dan

 

[TheOldHokie]

I have an L3301 and I checked how dealer did mine. I think it looks similar to this. At first glance, it's really confusing as I was expecting grapple/third function to be close to loader, but it's coming from the back. I got 2 remotes, and they're definitely first. 3point is 'locked in lower position' with the backhoe installed and dealer said don't touch it.

My third function isn't 1/4 inch hose... its like 1/2+... it's bigger than loader hoses.

My BH77 works great. Rapid movement unless I'm trying 3+ functions at once...you can do it, but it's more controllable and faster to only do 2 max...as soon as you try 3+, it significantly slows down.

Reason I found this post is one of my third function couplers (male) has tiny leak that starts when fluid is hot. Also a tiny leak around third function valve hoses. Land pride kit.

Interesting - what locks the 3pt lever? I can see the reasoning for it but nobody seems to have mentioned this previously.

Are you saying the dealer installed the 3rd function valve between the back hoe and the 3pt?

Dan

 

[minthral]

Interesting - what locks the 3pt lever? I can see the reasoning for it but nobody seems to have mentioned this previously.

Are you saying the dealer installed the 3rd function valve between the loader and the 3pt?

Dan

The 3point lever has a metal clip screwed so its stuck in lowered position.

I just took a look at it again... one hose connects to loader and other hose goes to the back to a block next to my 2 remote valves, both of which have separate connections elsewhere (didn't trace them, but I think its backhoe)...I guess this is the 3 point? Not sure. Backhoe is going off the block on the side, which also has 2 other connections to loader.

 

[TheOldHokie]

The 3point lever has a metal clip screwed so its stuck in lowered position.

I just took a look at it again... one hose connects to loader and other hose goes to the back to a block next to my 2 remote valves, both of which have separate connections elsewhere (didn't trace them, but I think its backhoe)...I guess this is the 3 point? Not sure. Backhoe is going off the block on the side, which also has 2 other connections to loader.

The block next to the remotes is the transmssion adapter for mounting the valves. The PB hose from the loader valve connects to a fitting on the underside of that block. The power beyond from the remote valve stack is on the fender end of the stack. Where does that hose go - to the backhoe or the third function valve?

Dan

 

[minthral]

The block next to the remotes is the transmssion adapter for mounting the valves. The PB hose from the loader valve connects to a fitting on the underside of that block. The power beyond from the remote valve stack is on the fender end of the stack. Where does that hose go - to the backhoe or the third function valve?

Dan

The backhoe connection is coming off the side of the remotes (narrow block there that attaches to 2 separate remotes that have hoses that go to remote quick connect). The other end of the backhoe connection is going to block next under the floor (power beyond port).

 

[minthral]

The backhoe connection is coming off the side of the remotes (narrow block there that attaches to 2 separate remotes that have hoses that go to remote quick connect). The other end of the backhoe connection is going to block next under the floor (power beyond port).

This is confusing so for me it's:

Power beyond: backhoe > remotes > grapple

Loader and 3 point is separate and T'd off.

 

[TheOldHokie]

This is confusing so for me it's:

Power beyond: backhoe > remotes > grapple

Loader and 3 point is separate and T'd off.

No offense but i think that would be very unusual. Standard L3301 plumbing is pump to loader via a fitting on the hydraulic block under the right floor board. From there the loader feeds the remotes via the block on the side of thectransmission. The tank return for the remotes is knternal through that block and into the side of the transmission. Where the power beyond goes from there is the question. The 3pt is last in the pressure side chain and is fed by a hose coming back forward to a fitting on the same hydraulic block under the right side floor board that starts the chain. You can't turn the 3pt off - its the tank return for the pressure side. All you can do is lock the lever down so the path to tank stays open.

Dan

 

[minthral]

No offense but i think that would be very unusual. Standard L3301 plumbing is pump to loader via a fitting on the hydraulic block under the right floor board. From there the loader feeds the remotes via the block on the side of thectransmission. The tank return for the remotes is knternal through that block and into the side of the transmission. Where the power beyond goes from there is the question. The 3pt is last in the pressure side chain and is fed by a hose coming back forward to a fitting on the same hydraulic block under the right side floor board that starts the chain. You can't turn the 3pt off - its the tank return for the pressure side. All you can do is lock the lever down so the path to tank stays open.

Dan

It's not a theory or a 'would be.' Dealer set it up just like this and it works fine. Once you get backhoe, remotes, and third function, it's not a standard L3301 with just loader...you must change stuff around to make it work. I specifically wanted them to do it so I wouldn't have to figure it out later.

As far as I'm concerned, makes sense to me... power beyond feeds backhoe first, then remotes, then grapple. What's wrong with that? The power beyond should be feeding the grapple if you don't have a backhoe. Or if you only have remotes, it should feed that. If you don't have power beyond port, it's going to be different.

Your L3901 have backhoe, remotes, and third function?

 

[PoTreeBoy]

Interesting - what locks the 3pt lever? I can see the reasoning for it but nobody seems to have mentioned this previously.

Are you saying the dealer installed the 3rd function valve between the back hoe and the 3pt?

Dan

Dan, here it is. It's part of the BH77 kit apparently.

 

[TheOldHokie]

The backhoe connection is coming off the side of the remotes (narrow block there that attaches to 2 separate remotes that have hoses that go to remote quick connect). The other end of the backhoe connection is going to block next under the floor (power beyond port).

That makes perfect sense. Your backhoe is the NEXT TO LAST valve in the pressure chain . Based on your description it receives its power from the remotes and returns flow to the pressure IN port on the hydraulic block. That port feeds the backhoe valve which returns straight into the sump.

The loader valve and 3rd function are undoubtedly ahead of the remotes. Most likely the loader valve is the first valve in the chain and receives power from the block under the floor board. It also has a direct tank return via the third port on that block. The 3rd function gets its power from the power beyond port on the loader valve and the tank port on it feeds the remotes.

100% standard Kubota and avoids the issue with the plumbing on the tractor that started this thread.

Dan

 

[TheOldHokie]

Dan, here it is. It's part of the BH77 kit apparently.

View attachment 71745

Perfect - a very reasonable attempt at GI proofing the system!!! Since you have the instructions what does it say about the backhoe supply and return connections? Judging by the pictures they are not for an L01 tractor but should still be informative..

Dan

 

[PoTreeBoy]

Perfect - a very reasonable attempt at GI proofing the system!!! Since you have the instructions what does it say about the backhoe supply and return connections? Judging by the pictures they are not for an L01 tractor but should still be informative..

Dan

I downloaded the instructions from Kubotabooks.com. Looks like it fits several (4?) brackets/tractors with different arrangements. But they seem to replace the hose from the loader valve power-beyond to hydraulic block hose with a loop of two hoses coupled together that go to the rear which can be uncoupled and connected to the backhoe when it is installed.
So the backhoe is between the loader and the 3PH, but it doesn't answer where the 3rd function is connected. Probably need those instructions. Looks like it could be either before or after the hoe with the swap of a couple of hoses.

 

[minthral]

That makes perfect sense. Your backhoe is the NEXT TO LAST valve in the pressure chain . Based on your description it receives its power from the remotes and returns flow to the pressure IN port on the hydraulic block. That port feeds the backhoe valve which returns straight into the sump.

The loader valve and 3rd function are undoubtedly ahead of the remotes. Most likely the loader valve is the first valve in the chain and receives power from the block under the floor board. It also has a direct tank return via the third port on that block. The 3rd function gets its power from the power beyond port on the loader valve and the tank port on it feeds the remotes.

100% standard Kubota and avoids the issue with the plumbing on the tractor that started this thread.

Dan

I'm confused... is the power beyond port IN or OUT (far left side looking at the block under the floor board, under the loader joystick side). This port goes straight to my backhoe and then if I disconnect backhoe, I connect a loop.

 

[PoTreeBoy]

. . . but it doesn't answer where the 3rd function is connected. Probably need those instructions. Looks like it could be either before or after the hoe with the swap of a couple of hoses.

Found instructions for a LP MX third function, they refer you to the dealer if a backhoe is installed .

 

[TheOldHokie]

I downloaded the instructions from Kubotabooks.com. Looks like it fits several (4?) brackets/tractors with different arrangements. But they seem to replace the hose from the loader valve power-beyond to hydraulic block hose with a loop of two hoses coupled together that go to the rear which can be uncoupled and connected to the backhoe when it is installed.
So the backhoe is between the loader and the 3PH, but it doesn't answer where the 3rd function is connected. Probably need those instructions. Looks like it could be either before or after the hoe with the swap of a couple of hoses.

The Landpride instructions tell you to plumb the third function into the power beyond on the loader by replacing the original PB hose with a shorter one and then plumb the 3rd function to the hydraulic block wher the loader PB used to connect.

The L01 remote instructions tell you to plumb the remotes into thst same loader port and power heyond on the remotes into that same port on the hydraulic block.

In other words plugging these individual pieces together is left up to the installer meaning the installer needs to understand each component.

Kubota is pretty closed mouth about these systems and I spent a lot of time studying the instructions and the hydraulic circuits on the L01 tractors in preparation for building my own auxiliary remote valve stack. I think I have a real good understanding of all of them and this is how I designed my circuitry.

The remote mounting block bolts to the side of the transmission, and is fed by the power beyond port on the loader valve. The tank return is through an internal passage in the block which connects to the OEM port on the side of the transmission. That is stock KUBOTA,

However my block has a D03 sub plate on the top for mounting the third function valve. The 3rd function is fed by the inlet port on the block and the tank return port on the third function feeds the remote valve stack that mounts to the side of the block.

The power beyond port on the auxiliary valve stack goes back to the pressure in on the front hydraulic block. Again just like OEM with the exception of the third function valve which is now part of the stack.

Given the back hoe comes with a 3pt lockout and back pressure warning label I think its safe to conclude the place it needs to go is between the auxiliary valve stack and the return to the 3pt.

Dan

 

[TheOldHokie]

I'm confused... is the power beyond port IN or OUT (far left side looking at the block under the floor board, under the loader joystick side). This port goes straight to my backhoe and then if I disconnect backhoe, I connect a loop.

You are getting close to understanding.

The upper right port is pump pressure OUT to auxiliary equipment.
The bottom center port is low pressure tank return from auxiliary equipment. It goes straight to the sump.
The upper left is high pressure IN from the auxiliary equipment. It powers the 3pt.

Dan