Backhoe & Power Beyond Question

[kennyd]

I actually was going to T into the 'In' line until I read your posts warning about that. I guess I thought I was doing the right thing by T'ing into the PB line - not so? So is the way I have it OK except I should have the return (i.e. the 'Out' from my new valve) go somewhere else? I have time to change this now because I'm not cutting hay again until next summer.
Marty

Marty,
You should have a hose that runs from the PB port on your loader valve to the IN port on the new valve. The PB port on the new valve should go to wherever the original line went to (presumably the 3PH). Then the OUT of the new valve should go to the tank. You CAN Tee low pressure return lines, but NOT high pressure lines.

If the new valve in placed in "parallel" with the loader valve, then the fluid will take the path of least resistance back to the tank, and that won't be through your new valve. ALL valves MUST be in "series"

Clear as mud?

 

[JDeereman]

Marty,
You should have a hose that runs from the PB port on your loader valve to the IN port on the new valve. The PB port on the new valve should go to wherever the original line went to (presumably the 3PH). Then the OUT of the new valve should go to the tank. You CAN Tee low pressure return lines, but NOT high pressure lines.

If the new valve in placed in "parallel" with the loader valve, then the fluid will take the path of least resistance back to the tank, and that won't be through your new valve. ALL valves MUST be in "series"

Clear as mud?

Kennyd - i don't think that valve has a pb port. just in and out ports. all he can do is feed it from fel pb and return flow to the next-in-line pb user (in series as you point out). not ideal and potentially dangerous per discussion above but otherwise he needs a valve with pb.

Theo

 

[mgrohman]

Thanks for the comments. Theo is right, the new valve doesn't have a PB port. It has an open center design, so to my (probably flawed) way of thinking, the FEL setup doesn't know it's there unless I actuate said new valve, which is fairly rare. Basically I only raise the Mower Conditioner if I am going to run over something, like maybe a finance manager.
This tractor, a Kubota L3710, does not have external cylinders for actuating the 3PH. I have the 'out' from the new valve going back to where the PB went before, which looks to me like it is a tank return. I will see if I can consult the appropriate page in the book and possibly scan and post it here. Essentially what you're telling me is, if I actuate this valve while I have something raised with the 3PH, I could cause myself a sichyation, correct?
Marty

 

[JDeereman]

Thanks for the comments. Theo is right, the new valve doesn't have a PB port. It has an open center design, so to my (probably flawed) way of thinking, the FEL setup doesn't know it's there unless I actuate said new valve, which is fairly rare. Basically I only raise the Mower Conditioner if I am going to run over something, like maybe a finance manager.
This tractor, a Kubota L3710, does not have external cylinders for actuating the 3PH. I have the 'out' from the new valve going back to where the PB went before, which looks to me like it is a tank return. I will see if I can consult the appropriate page in the book and possibly scan and post it here. Essentially what you're telling me is, if I actuate this valve while I have something raised with the 3PH, I could cause myself a sichyation, correct?
Marty

Marty - that old fel pb out line had to be going somewhere. i assume you have no backhoe. do you have a rear remote set? does your pb feed the 3-point? the 3-point doesn't need to have external cylinders to use pb. the physical connection to the 3-point may not be real obvious.

but if your pb line really wasn't there to feed anything and was just routed back to a tank return point for some possible future use, then you are fine once you change the fel pb out "tee" that you spoke about to a simple series connection as kennyd had pointed out.

Theo

 

[kennyd]

On most CUT's like JD's and the Kub's the 3PH is the last valve in the circuit. I will bet that PB line terminates to the tranny case, where internally it feeds the 3PH.

I will venture to say all you need to do is remove that T you have, and leave the OUT port go to where the PB line went to and you will be fine.

 

[mgrohman]

Kenny - I misspoke - I guess I meant that functionally I 'Teed' into the lines, but in actuality, I did have new hoses made that fit into the existing quick-disconnect junction in that PB line - basically I undid that quick-disconnect, and connected my new hoses. These are the in and out for my new valve. So I don't have any actual Tees in my system. This was based on some of your very good posts on the matter, that one should avoid Tees in hydraulics. In fact I bought some Tees before I read your posts and have to return them.
Marty

 

[kennyd]

Kenny - I misspoke - I guess I meant that functionally I 'Teed' into the lines, but in actuality, I did have new hoses made that fit into the existing quick-disconnect junction in that PB line - basically I undid that quick-disconnect, and connected my new hoses. These are the in and out for my new valve. So I don't have any actual Tees in my system. This was based on some of your very good posts on the matter, that one should avoid Tees in hydraulics. In fact I bought some Tees before I read your posts and have to return them.
Marty

So then, I apologize for busting your chops Sounds like you are good-to-go then with the way you have it!

I was basing ALL of my comments on what you wrote in your first post:

I basically had hoses made that Tee into the line that comes out of the 'PB' port on my loader control valve (pointing to it with my knife in the picture; the one I Teed into is to the right of the blade).

 

[mgrohman]

That's OK - I deserve it! I wrote it wrong.
On another topic I've seen debated - I did use the white Permatex thread sealer on all of the pipe threads, like in and out of the new valve. I would say it's definitely needed, because I left it off of one fitting by accident, and it leaked.
Of course the sealer should be avoided on any compression-type fitting like the PB port on the loader valve.
Marty

 

[Willl]

I would do it the way JD does on the mid-framed CUT's...That is to add three QD's to the rear instead of two like you suggested. The third is just a hose for the return-to-tank line.
So you would have three connections at the rear:

>PB Out
>PB In (goes to the 3PH)
>RTT Return to tank for backhoe operation.

Hi Kenny, this makes me question how the heck my 790 is plumbed for it only has 2 connections at the rear for my BH. (see attached)

I know my 3pt is still alive with the BH in circuit cause I can still hydraulically raise them for alignment during BH installation. But this doesn't make any sense beings the BH has only 1 return line. Does not 1 return line from the BH mean it MUST go directly to the tank ?

With a 2 connection setup like mine, what would happen if I forgot to rehook my return line after removing BH and started the tractor ? Instant system relief noise ?

If I wanted to add aux valve for TNT or whatever, what plumbing setup would be advisable ?

Studying my hyd schematic, seems the steering circuit just loops around and never sees the filter. I'm I seeing that correctly ?

 

[kennyd]

Hello Will

Hi Kenny, this makes me question how the heck my 790 is plumbed for it only has 2 connections at the rear for my BH. (see attached)

I know my 3pt is still alive with the BH in circuit cause I can still hydraulically raise them for alignment during BH installation. But this doesn't make any sense beings the BH has only 1 return line. Does not 1 return line from the BH mean it MUST go directly to the tank ?

The small CUT's like mine and the 2305, 2320, 2520 only have the one return for the PB circuit and that feeds the 3PH. There was a change in the mid-framed CUT's in the PB kit that added the extra QD that is a direct return-to-tank line (look in JDParts and you will see OLD and NEW under the PB for like a 4300 and 4400 series machines)
So in the tractors like ours with only one return, the 3PH stays active all the time.

With a 2 connection setup like mine, what would happen if I forgot to rehook my return line after removing BH and started the tractor ? Instant system relief noise ?

You got it! Instant relief for sure. If you left it running like that than overheating of the hydraulic fluid would occur and possible pump damage.

If I wanted to add aux valve for TNT or whatever, what plumbing setup would be advisable ?

Just put the new valve in-line, the PB port is not needed in this case. I have done it to my tractor as well as quite a few others who have 2520's. I can link some post's if you want?

Studying my hyd schematic, seems the steering circuit just loops around and never sees the filter. I'm I seeing that correctly ?

Not 100% sure here...but I would guess since the fluid is all in the common sump it has to be filtered at some point?