Can you identify a hydraulic control valve with a float position visually?

[mslisaj]

I have a six spool hydraulic control valve on my back hoe. It is supposed to have a float position on one of the spool valves and I believe I have identified that position because it has a longer "cap" at the bottom of the valve and at the end of the spool. I "believe" this longer cap houses a spring and is where the spool will be pushed into for the longer reach of the special valve to allow float. I am no hydraulic expert at all. I have read the hydraulic schematic for this valve and there appears to be an extra position or valve that will join the two ports together for the float and thus a "longer valve".

My question here to you men that know hydraulics, is my assumptions correct here? I realize this is kind of a generic question but I am looking for that generic answer. I can not push the valve (or control) into the float position and I am thinking there is something in that "cap" that is preventing it from moving into this position like a spring in the wrong place or something kind of simple - a mechanical block or debris. Again, I am just asking if my "theory" of operation is correct here and can I use that theory for a visual and diagnostic inspection.

Thanks for your help and response.

 

[oldnslo]

Yes your theory of the longer cap points towards a fourth position for that spool which could be float

 

[mslisaj]

Thank you "oldnslo" for taking your time to respond to my question here. This is kind of a baptism of fire as I'm learning this stuff as I go along. Years ago I had training and would rebuild automobile automatic transmissions. But this kind of hydraulics I have no real experience in. So I'm just learning it carefully as I go along.
Again thank you for pointing me in the right direction.

 

[newbury]

As always a picture with the parts in question pointed out and labeled would help greatly.

 

[s219]

Usually, valves with a longer can at the bottom do have float, and you’ll find the spring plunger with ball bearings down on that end, which are used to lock the valve into a detent. But normally unless there are other similar non-float valves to compare to, you can’t tell. There are also standard valves that don’t float but do have a detent that will look similar from the outside. So while we can make an educated guess, it’s hard to say for sure only looking at the outside.

 

[mslisaj]

Usually, valves with a longer can at the bottom do have float, and you値l find the spring plunger with ball bearings down on that end, which are used to lock the valve into a detent. But normally unless there are other similar non-float valves to compare to, you can稚 tell. There are also standard valves that don稚 float but do have a detent that will look similar from the outside. So while we can make an educated guess, it痴 hard to say for sure only looking at the outside.

Thank you gentlemen for taking your time to respond here. I'll pull the cover and get in there and look. Here is also a picture of the "hydraulic schematic" that clearly shows the "float" valve.

This is the basis for my question. I have a brand new machine with all indications of a float on the boom position. From the manual to the schematic. But my tractor "does not float". Will not go into the "detent" position or that extra bit of travel. I have been trying to determine if the valve was not set up for the float or it's defective. So a visual inspection of the longer cap will give me the clue. As I started this is a generic question and I realize there can be other possibilities but you men have launched me in the right direction to answer my basic question and I so appreciate that. When I get that cover off I'll take a picture and post it here. But I so appreciate your help.

Best regards,
Lisa

 

[mslisaj]

Well gentlemen you all have gone way beyond helpful to me here and I can't thank you enough. I finally had time to pull the inspection cover and all the end caps on the spool valves are exactly the same. The pictures here aren't the best but you can see in the two from slightly different angles that the caps across the valve are the same. Without tearing the valve apart I am going to make the assumption that this valve was not equipt with a "float" spool and detent assembly. I'm okay with this discovery as I explained I was more concerned that I may have something that is not operating correctly. While the manual and schematic discusses the "float" this perticular valve was apparently not set up with that option.

Again, I sincerely thank all of you for taking your time to share your expertise with me on this. Everyone made a huge contribution to helping me solve the mystery. Plus I learned more about my tractor and the hydraulic systems.

Best regards and Merry Christmas. :thumbsup: :drink:

Lisa

 

[/pine]

Just curious...what action on a backhoe would you want to set in 'float'?

 

[/pine]

BTW...the pictures show the working ports...not the bottom end caps?
edit...I guess you can see the caps through the hoses...disregard...

 

[tnjind]

I would think if you operated each valve then the one with float will move farther and you can feel it go into the detent.

 

[the old grind]

Schematic shows the boom cylinder uniquely has a 'float' position that connects both ports to the 'return' line in circuit. It's represented as the one closest to the intake port.

'What tnjind said' .. that you should feel that valve toggle into its detented position.

This is a good example of flow paths in a 'Closed Center' stack. I hope it suits the OP's application and supply system. Note that there is also no 'power beyond' port in the picture .. not needed with CC. See that flow doesn't return to tank with valves in neutral positions.

btw, what's shown as pressure relief in the supply section is also called an 'unloader' (a high volume relief valve) spring-adjusted to maintain circuit pressure and by default dump excess flow to tank.

 

[mslisaj]

Well "/Pine" I am new to operating backhoes and am in a steep learning curve. In the owners manual for this machine they talk about a float on the boom "down" position. Where it would be adventagous is in cleaning out the bottom of a trench. You would put the bucket flat down on the bottom and float the boom. Then just pull back on the "dipper" and adjust the bucket curl to keep it at the bottom. There are two advantages to this: 1) the dipper and curl have more available hydraulic pressure if they needed it and 2) it's easier. I didn't know this "option" even existed and I have been practicing this same movement using all thee modes or valve (boom, dipper and bucket curl) and getting pretty good at it. This only became an issue for me when I read the operators manual and they talked about this feature. Then I googled it and watched a YouTube about it and thought it was a pretty good idea. Well when attempted to put the boom into the detent/float position it would not go into that detent as the loader valve will do. Now I was concerned that I had a system on my new machine that was defective and didn't work. The book says it was there and but it wouldn't work. So I have been on a three day quest to find out what is "wrong" and why it won't work. You can not believe how many people, including the dealer that sold me the machine didn't know anything about it. Finally I came here with a generic question and you men nailed it for me right away. The option was obviously not installed in to this control valve. Yes the picture was poor but it was the best I could do and you can see - kind of - all the valve caps are the same behind the hoses. So for me the mystery is solved. The valve is work as it was assembled. The option of "float/detent" was not installed. Again you guys nailed it for me and thank you.

 

[mslisaj]

Schematic shows the boom cylinder uniquely has a 'float' position that connects both ports to the 'return' line in circuit. It's represented as the one closest to the intake port.

'What tnjind said' .. that you should feel that valve toggle into its detented position.

This is a good example of flow paths in a 'Closed Center' stack. I hope it suits the OP's application and supply system. Note that there is also no 'power beyond' port in the picture .. not needed with CC. See that flow doesn't return to tank with valves in neutral positions.

btw, what's shown as pressure relief in the supply section is also called an 'unloader' (a high volume relief valve) spring-adjusted to maintain circuit pressure and by default dump excess flow to tank.

Well "the old grind" I so appreciate that explaination. A lot technical for me but I get it as I traced it out like that. But bottom line is you need that special spool valve there to do it and have the detent. Apparently my valve does not have this valve or feature installed. The point was made by "s219" that a longer "can" at the bottom would be an indication of this longer spool and detent. All six of the "cans" on my valve are identical which leads me to assume that all the spool valves are identical too. This no detent position and not float.

I should have come to this forum first as you men have the good technical answers and that is what I needed.

Sincerely thank you.

Lisa

 

[JRobyn]

The float detent caps/springs on my Kubota rear hydraulic valves are VERY prominent. Can't miss 'em. Big cylinders on the right.

 

[mslisaj]

The float detent caps/springs on my Kubota rear hydraulic valves are VERY prominent. Can't miss 'em. Big cylinders on the right.

View attachment 532651

Yep!! And my machine has none of that.

 

[/pine]

Well "/Pine" I am new to operating backhoes and am in a steep learning curve. In the owners manual for this machine they talk about a float on the boom "down" position. Where it would be adventagous is in cleaning out the bottom of a trench. You would put the bucket flat down on the bottom and float the boom. Then just pull back on the "dipper" and adjust the bucket curl to keep it at the bottom. There are two advantages to this: 1) the dipper and curl have more available hydraulic pressure if they needed it and 2) it's easier. I didn't know this "option" even existed and I have been practicing this same movement using all thee modes or valve (boom, dipper and bucket curl) and getting pretty good at it. This only became an issue for me when I read the operators manual and they talked about this feature. Then I googled it and watched a YouTube about it and thought it was a pretty good idea. Well when attempted to put the boom into the detent/float position it would not go into that detent as the loader valve will do. Now I was concerned that I had a system on my new machine that was defective and didn't work. The book says it was there and but it wouldn't work. So I have been on a three day quest to find out what is "wrong" and why it won't work. You can not believe how many people, including the dealer that sold me the machine didn't know anything about it. Finally I came here with a generic question and you men nailed it for me right away. The option was obviously not installed in to this control valve. Yes the picture was poor but it was the best I could do and you can see - kind of - all the valve caps are the same behind the hoses. So for me the mystery is solved. The valve is work as it was assembled. The option of "float/detent" was not installed. Again you guys nailed it for me and thank you.

Thank you for the informative explanation...I can easily see where the longer the reach of a hoe the more this action would be especially beneficial...
My hoe has a short reach and maintaining a smooth ditch bottom grade can be quite taxing on my skills...

If you're interested...there may be a (float) detent kit for your valve... they are not difficult to install...usually access is the issue...

 

[FTG-05]

$10 says you can figure it out*:

ETA: In case of the idiots out there: Not a real bet.

 

[mslisaj]

Thank you for the informative explanation...I can easily see where the longer the reach of a hoe the more this action would be especially beneficial...
My hoe has a short reach and maintaining a smooth ditch bottom grade can be quite taxing on my skills...

If you're interested...there may be a (float) detent kit for your valve... they are not difficult to install...usually access is the issue...

Well "/pine" you bet I'm looking for a kit. LS says there is not one available but I will contact some hydraulics shops and figure out what we can do. The valve in my hoe can't be that special. Especially when it looks like from the description in the book and the hydraulic schematic that there once was the float option. Putting it in would be easy too. Already figured out the moves. Don't even have to disconnect the lines. Unbolt the valve from the mount, lay it down, remove the control lever from the top of the valve, remove the cap and spring. Remove the spool and install the new parts and seals and your back on the streets again. If I can buy the parts I will have this option in my hoe. Plus for no other reason then to say I got it.

All you guys have been a HUGE help here and give me the confidence to get it done. Just need the parts.

Best regards,

Lisa

 

[mslisaj]

$10 says you can figure it out*:

ETA: In case of the idiots out there: Not a real bet.

I had that figured out before you finished typing it
Gotta love hydraulics - it's just wet wiring........... :thumbsup:

 

[FTG-05]

I had that figured out before you finished typing it
Gotta love hydraulics - it's just wet wiring........... :thumbsup:

I rest my case....