Help ordering hydraulic fittings (for rear remote)

[rswyan]

I've got a million little projects going on. Sawmilling wood, carpentry, fixit projects, maintenance. Its been raining and had burnpiles going too, and I can always find more stuff to clean up.

I hear ya Brother ... if I cloned myself 5 times I'd still be short a few hands ...

So nice to be out in the woods - right now everything's green, vibrant, wildflowers out in force and you can almost hear the trees getting thicker.

Yup ... our house in surrounded on three sides by woods ... everything "popped" to life (green) within the last couple of weeks.

A big part of what I love about it - beyond the greenery and plant life - is the birds ... their cacophony is usually incessant ...

I love the Life of it ...

And my burnpiles, they seem to command respect, and gifts, incessant gifts. All I can say is it's really great exercise, and I can huck a stick farther than anybody and get it to land exactly in the intended location on the pile.

Sounds like fun

Thanks for that pic RS.

You betcha ...

My hoses go forward to this little rectangular unit, which I did not investigate (yet).

The FEL hydraulic block (not the valve) is located at the top, towards the center in the picture you provided. Two hoses are shown connected to it.

It is possible that your B7800 lacks the holes/machining to actually have a rear hydraulic block installed ... the B7800's may not have come with them (the holes) ... on that count, I dunno ...

If that is the case, then one would use the FEL hydraulic block as the source for any (external) hydraulics ... so the use of that FEL hydraulic block isn't, in and of itself, necessarily an incorrect way to do it.

The potential problem lies in how one actually plumbs the thing. Like most things of a technical nature, there is a correct way to do it, and an incorrect way.

However, unlike most things, doing some things the wrong way with hydraulics can have some pretty serious consequences ... even potentially deadly consequences. And fluid injection injuries are pretty nasty things.

As I understand it, in an open-center hydraulic system, things (valves mainly) are plumbed in series ... and valves have three connections, beyond the valve connections (aka "A/B work ports") that supply the devices the valves are controlling.

The three connections are:

1. Inlet/Supply
2. Power Beyond to feed any valves downstream (high flow, high pressure)
3. Outlet/Return to tank/reservoir (high flow, low pressure)

The reason for the 3rd item above is that most valves typically don't like to have their outlets (the return) pressurized to any significant degree.

It is certainly possible to do things in a technically incorrect manner and have them "work" ... at least until they break ...

A good example of that is using a black pipe fitting - which isn't designed for high pressure - in a place on a hydraulic system where high pressure will be present. It may work for a time ... until it ruptures or explodes ...

Beyond the safety aspect, there is the issue of (permanently) placing a (constant or continual) restriction (or multiple restrictions) in the flow path of a hydraulic system. Dunno for sure - and maybe someone better informed than I will chime in - but I would think that that perhaps might not be a good thing, for various reasons.

I assume that you - like most on TBN - are not a man of unlimited means and do have at least some interest in ensuring that you don't tear up or damage your equipment ... particularly as a consequence of someone else's stupidity ...

Your incredulity piques my interest and I will look further, what that square block is. What would I use 6 gpm (vs 4.5) for that will benefit me? I don't recall tapping my foot waiting for the TnT.

Probably not ... usually - at least in my experience - with TnT one is looking for less flow ... in order to slow things down, to afford more precise control.

What gpm do I "need" for a splitter for example?

Only you can answer that:

How fast do you wanna go ?

 

[rswyan]

BTW ... the hose you have labeled in the picture as "rtn" (return) likely isn't a "return" ...

Based on where it's heading, it is likely supplying the FEL valve ...

If that's indeed the case, then the line is functioning in a practical sense as a power beyond connection (should be high flow/high pressure) ... possibly while hooked up to the return outlet (should be high flow/ low pressure) on your rear valve.

The actual return line (for the FEL valve) is the hose you didn't label ... which appears to be heading from the FEL valve to the general area on the tractor where the return port on the case is located - which is just above the leftmost arrow in the picture.

 

[Sodo]

I hear ya Brother ... if I cloned myself 5 times I'd still be short a few hands ...

Not me if they were my clones they'd avoid the drudgery and I'd have to armwrestle 'em for the best jobs. Armwrestling a clone, by definition, is a fools game.

BTW ... the hose you have labeled in the picture as "rtn" (return) likely isn't a "return" ...

Based on where it's heading, it is likely supplying the FEL valve ...

If that's indeed the case, then the line is functioning in a practical sense as a power beyond connection (should be high flow/high pressure) ... possibly while hooked up to the return outlet (should be high flow/ low pressure) on your rear valve.

The actual return line (for the FEL valve) is the hose you didn't label ... which appears to be heading from the FEL valve to the general area on the tractor where the return port on the case is located - which is just above the leftmost arrow in the picture.

OK you're right, I called it a 'rtn' because it's the smaller line from the rear hydraulics. It goes to the "IN" port of the FEL valve block (lower right hose in this pic). The big one at upper left is the yellow-banded hose going to that "block". The lower left hose goes to the "tranny", I'm assuming to the 3-pt lift.

The yellow-banded hose from the FEL valve block.

Do you understand my system & do you think it's configured "correct"?

 

[rswyan]

Do you understand my system ...

I have a fairly decent understanding of the hydraulic system on my B2910 ... and since the B2910 and the B7800 are quite similar, yeah ... I probably have a fairly decent understanding of the hydraulic system on your tractor ... save for how your rear remotes are plumbed and connected up ...

... & do you think it's configured "correct"?

Hard to say for sure at this point ... part of the issue is probably some confusion about the terminology we're using to describe things. That might be partially cleared up at this point, but let's review ... just to make sure we're on the same page:

Power Beyond: An outlet on a hydraulic valve which allows full fluid flow (and pressure), and extends the hydraulic fluid loop to other valves downstream. Can also be used to refer to a portion of that fluid path. Only required if one wants to have additional valves downstream. A power beyond line/hose is the supply when you get to the valve downstream that it is feeding.

Return: An outlet (and/or associated line/hose) on a hydraulic valve which dumps directly back to the tank/reservoir. Also used to refer to the port on the tractor that goes to the tank/reservoir and which return lines/hoses are connected to. There should be no additional valves plumbed into a return line. IOW: nothing plumbed in that is capable of placing a restriction on the flow in the line.

Return lines/hoses are often sized larger than pressure lines ... to reduce pressure in the line/hose, slow the fluid, and because valves typically don't like to have their return outlets pressurized (bad juju)

Supply: An inlet on a valve into which fluid under pressure is fed. Can also be used to refer to the port/outlet/output from the hydraulic pump from which the fluid flow comes. Supply can come from the outlet on hydraulic pump ... or the power beyond outlet on a hydraulic valve (upstream of another valve it is supplying)

(Auxiliary) Hydraulic Block: the device on the tractor which provides a pair (usually) of ports (in/out) for external hydraulic devices ... neither of these ports is a "return" in the technical sense ... because they don't dump back to the tank/reservoir ... at least on the tractors we're talking about. They are part of the hydraulic (pressure) loop ... and the "inlet" on either of them essentially provides "power beyond" to the next device (valve) in the chain.

A "hydraulic block" is not the control valve itself, nor is it on the valve.

When referring to a hydraulic valve please use "valve body" ... and not "valve block" so as to avoid adding confusion.

On my tractor (B2910) there are two hydraulic blocks - one at the mid-point (shown in your pictures) ... and an additional one at the rear (shown in an illustration I previously posted), which I installed, which provides fluid flow (via it's outlet) for my rear remote valve (3 spool Prince SV stack valve), and a power beyond path (via it's inlet) to supply the (internal) valve which controls the 3PH.

On my tractor here's the flow path for pressurized fluid (minus returns):

Output from hydraulic pump ---> outlet on mid hydraulic block

Outlet on mid hydraulic block ---> inlet on FEL control valve

Power beyond outlet on FEL control valve ---> inlet on mid hydraulic block

Inlet on mid hydraulic block ---> outlet on rear hydraulic block (This part of the flow path is internal inside the tractor, and if I didn't have the rear hydraulic block installed, the inlet on the mid hydraulic block would be feeding the valve - which is internal - that controls the raising and lowering of the 3PH)

Outlet on rear hydraulic block ---> inlet on 3 spool Prince SV valve (which are my rear remotes)

Power beyond outlet on 3 spool Prince SV valve ---> inlet on rear hydraulic block

Inlet on rear hydraulic block ---> 3PH control valve (internal on the tractor)

Return outlet on 3PH control valve ---> tank/reservoir (flow path is internal on the tractor)

Additionally, each external valve body (FEL and rear remotes) has a separate return outlet and associated line/hose which dumps back to the tank/reservoir. These lines connect to a tee which is connected to a port (which is on the tractors rear case) and is located under the seat, on the right hand side of the tractor. See illustration from the LA 402 manual below, depicting the location of the return port on the tractor's case:

These "return lines" provide a flow path to dump excess fluid back to the tank/reservoir when the valve is being worked and it goes into relief (ie. the control valve's own built-in pressure relief valve is activated)

OK you're right, I called it a 'rtn' because it's the smaller line from the rear hydraulics.

Smaller line from the rear hydraulics what ? (a rear hydraulic valve ? a rear hydraulic block ? a rear hydraulic port on the tractor's case ? what ?)

BTW - return lines are typically the same size or larger than pressure/supply lines.

Depending on what specifically it is connected to on the rear, I may not have been correct.

It goes to the "IN" port of the FEL valve block (lower right hose in this pic).

If that is true (and I have my doubts), then it sure ain't a "return line" ...

Functionally, it would be acting as "power beyond" - by virtue of the fact that it's supplying the FEL valve. But I don't know that you are correct in your assessment or description of things.

What makes you think it's connected to the "IN" port on your loader valve ? Is there an "IN" imbedded in the valve's casting ?

FWIW, the hydraulic supply source for your FEL valve should be the hose with the yellow band around it, shown in the last picture. That's based on the fact that the right (forward) port on the mid hydraulic block is the output from the tractor's hydraulic pump - see the illustration from the LA 402 manual below:

What I really wanna know is this:

Does your rear remote valve assembly have three hoses connected to it (supply/inlet, power beyond, and return), not counting whatever hoses there are, that are connected to your TnT cylinders ?

The big one at upper left is the yellow-banded hose going to that "block".

That hose - the one with the yellow band - should be the hose that is supplying the FEL valve.

And the hose you have labelled in the last photo as "supply" ... what exactly do you think it's supplying ?

The lower left hose goes to the "tranny", I'm assuming to the 3-pt lift.

Probably not - it is more likely the return line ... which dumps back to the tank/reservoir.

 

[Sodo]

I apologize I'm getting things all mixed up by not knowing much about hydraulic systems, causing a lot of extra typing and time. I probably better stop describing my system until I get the component names right. I understand a cylinder for sure, but how a systems allows me to operate the TnT without the FEL dropping, that's beyond me at the moment. And it makes sense the return hose is larger, :ashamed:, it dumps back to the tank causing minimum 'back pressure'.

There are 3 ports on the FEL (______) <insert name> two of which have cast "IN" and "OUT". There are two ports on my "rear hydraulics" (______) <insert name> one hard-plumbed and one with a (larger) 'QD coupling'.

Thanks for taking the time! Gonna have to try to absorb this on the computer a little later (not phone). Also I have a B2710 not 7800.

I'd like to see a schematic of the whole system (or similar system). Does anybody know of a schematic of a tractor system with rear hydraulics that might be representative of what I have do I can see how its arranged (and the component names).

 

[Leejohn]

Maybe this help you guys.

 

[rswyan]

I apologize I'm getting things all mixed up by not knowing much about hydraulic systems, causing a lot of extra typing and time.

No worries ... it was good exercise ... just don't tell my wife

I probably better stop describing my system until I get the component names right.

Nah ... just keep stabbin' at it ... we'll get it all sorted out eventually ...

I understand a cylinder for sure, but how a systems allows me to operate the TnT without the FEL dropping, that's beyond me at the moment.

Quick explanation:

Hydraulic pump generates flow, and as soon as that flow encounters a restriction or something to work against (aka a "load") pump begins to build pressure.

Flow, under pressure, accomplishes work (extending a cylinder to raise the FEL)

The control valve provides the fluid flow (from the pump) to the device (say, a cylinder) by the user using the control valve's handle to open the work ports on the valve , allowing fluid to flow into one end of the device, and out of the other end (of the device)

Move the control valve handle one way and the fluid (under pressure) goes to one port and comes out of the other. Move the control valve handle the other way and the "into" and "out of" reverses.

As soon as you let off the control valve's handle, the hydraulic fluid is locked into the device, at whatever amount is present in either end of the device.

Fluids do not really compress very well, if at all - hence there is "holding power" - the ability to sustain or support a load, while under pressure.

The flow from the hydraulic pump at this point just flows through the FEL control valve back to the rear remotes ... and is available to power whatever devices (TnT) connected there.

Easy-peasy ...

And it makes sense the return hose is larger, it dumps back to the tank causing minimum 'back pressure'.

Correct.

There are 3 ports on the FEL (______) <insert name> two of which have cast "IN" and "OUT".

Good. The one port (that is unlabeled ?) should be the power-beyond outlet. It could be labeled "BY" or "PBY" I think.

There are two ports on my "rear hydraulics" (______) <insert name> one hard-plumbed and one with a (larger) 'QD coupling'.

That is what I suspected ...

That may be a problem ... because it doesn't appear to have a power-beyond outlet ... and yet it is being used (via it's return) to provide power-beyond capability to another valve downstream of it (the internal valve inside the tractor that raises and lowers the 3PH) ... via the hose (labeled "supply" in your photo) that connects the rear valve to the mid hydraulic block.

Hopefully someone really knowledgeable on hydraulics - like J J or wychd or IceStationZebra (?) - will chime in on this aspect (non power-beyond valve being used in a power-beyond application)

Thanks for taking the time!

You're quite welcome - hope you find it useful.

Gonna have to try to absorb this on the computer a little later (not phone).

Understand.

Also I have a B2710 not 7800.

DOH ! ... that's right ... sorry

I'd like to see a schematic of the whole system (or similar system). Does anybody know of a schematic of a tractor system with rear hydraulics that might be representative of what I have do I can see how its arranged (and the component names).

I could check the WorkShop Manual for my B2910 and see if there is anything listed in there.

I suspect part of the problem with that will be that it only covers the tractor itself, and not the FEL ... or anything that wasn't original equipment from the factory.

 

[J_J]

Most modern hyd valves are designed to use a port called power beyond with an adapter to pass the pump flow downstream.

Most manufacturers say to run the tank port to tank as the port is only rated to about 500 psi.

When the valve that uses the tank port for supply is in a series flow path, any valve downstream can operate and cause back pressure and perhaps damage the valve seals or crack the casing, and cause problems with valves upstream.

There will be people that say we did it that way for all those years and nothing happened.

Well, if nothing happened, why did they start designing valves with the PB port.

The point here is that if you do use the tank port for pressure, then you risk your valve.

If you don't know, the PB adapter separates the flow from the expended cyl fluid and the relief flow, and allows the pump flow to continue downstream..

 

[rswyan]

J J,

Thanks.

 

[Sodo]

but how a systems allows me to operate the TnT without the FEL dropping, that's beyond me at the moment.

A PB port must be a check valve. Is this correct? Otherwise the FEL would drop.