Kubota B2920 Power Beyond Port

[GPintheMitten]

I have a question.
I have a B2620. When I bought a BH65 backhoe, I plumbed the hydraulics for the backhoe the way the OP is planning.
I was told not to raise the 3 pt while the backhoe was plumbed in or it would damage the valve (loader valve I think). This was from instructions from woods backhoe install that I got off the Internet.

When the hoe is off, these lines are connected to each other.

So if I wanted top-n-tilt would I put the valves between the connectors for the hoe loop?
What about the warning not to use the 3pt lift?

 

[s219]

I have a question.
I have a B2620. When I bought a BH65 backhoe, I plumbed the hydraulics for the backhoe the way the OP is planning.
I was told not to raise the 3 pt while the backhoe was plumbed in or it would damage the valve (loader valve I think). This was from instructions from woods backhoe install that I got off the Internet.

When the hoe is off, these lines are connected to each other.

So if I wanted top-n-tilt would I put the valves between the connectors for the hoe loop?
What about the warning not to use the 3pt lift?

Normally on Kubotas, power beyond flows from the hydraulic block outlet to the front loader, then to the rear remote, then to the backhoe, then to the 3-pt hitch, in that order. You can delete any of the items in the middle but the outlet is always the source and the 3-pt is always last. The 3-pt dumps directly to reservoir when idle or when in use and has no provisions to pass PB flow.

The Kubota factory rear remote valves are PB-capable, meaning they can pass the PB loop onto the next in line. Those valves have PB input (from loader's PB output), supply/return to implement, return to tank (a port if the valve mounts to the transmission case, otherwise a hose), and PB output to go to the next in line. You can get third party valves with the same arrangement. For a top and tilt setup where you also probably are using the 3-pt, you need these types of valves. In that situation, it doesn't matter what happens upstream or downstream -- the valves always have a path to return or continue flow.

Many backhoes make the assumption that the 3-pt hitch is not used, and that means they can get away with a PB-input line and a single return that they assume "always" dumps back to the reservoir (i.e., the 3-pt will never actuate and back pressure the line). I have seen backhoe kits that even come with a lockout for the 3-pt lever. If you actuated the 3-pt hitch in this scenario, it would back pressure the only return path that the backhoe is using. The backhoe valve doesn't have another independent return, so that would be bad.

The 3-pt hitch valve makes the same assumption, but since it's always meant to be last in line, it would never be a problem -- it never has to worry about something downstream back pressuring the line.

 

[GPintheMitten]

Thanks S219.

 

[s219]

Forgot to add the actual answer to your question -- if doing it in true Kubota fashion, you would insert PB capable rear remote valves upstream of the backhoe lines. Those valves would have their own return lines, so you can use the 3-pt. I'd see only minor benefit to plumbing them in using the backhoe lines, since you would absolutely need to add another separate return line anyhow. May as well do it right.

 

[GPintheMitten]

Forgot to add the actual answer to your question -- if doing it in true Kubota fashion, you would insert PB capable rear remote valves upstream of the backhoe lines. Those valves would have their own return lines, so you can use the 3-pt. I'd see only minor benefit to plumbing them in using the backhoe lines, since you would absolutely need to add another separate return line anyhow. May as well do it right.

Ok now I'm confused. When I use my subframe mounted backhoe, I don't use the 3 pt lift and would have no need to use the TNT.

Could I put the TNT valves upstream of where the backhoe would be connected and have the pb for the last valve continue to the 3pt?

Then when I connect the backhoe, I would connect the input to the hoe to the pb of the last TNT valve and the output from the hoe to the hose or line going to the 3pt?

 

[TMGT]

Ok now I'm confused. When I use my subframe mounted backhoe, I don't use the 3 pt lift and would have no need to use the TNT.

Could I put the TNT valves upstream of where the backhoe would be connected and have the pb for the last valve continue to the 3pt?

Then when I connect the backhoe, I would connect the input to the hoe to the pb of the last TNT valve and the output from the hoe to the hose or line going to the 3pt?

Yup, that's how I did mine, the feed line for the backhoe comes off my rear remote valves.

 

[J_J]

Where you put additional valves does not matter if you follow the PB to IN of the next valve.

With all valves in neutral, the flow passes through all valves to tank.

All return lines go to tank.

Some BH configuration send the return hose directly to tank, by passing the 3pt.

The BH return hose should never go to the 3pt.

If the BH has three hoses, then the PB from that valve goes to the 3pt and the return hose goes to tank.

 

[TMGT]

Where you put additional valves does not matter if you follow the PB to IN of the next valve.

With all valves in neutral, the flow passes through all valves to tank.

All return lines go to tank.

Some BH configuration send the return hose directly to tank, by passing the 3pt.

The BH return hose should never go to the 3pt.

If the BH has three hoses, then the PB from that valve goes to the 3pt and the return hose goes to tank.

Factory Kubota plumbs the BH on some models this way, the B2620 only has the pb line from the loader valve to feed the BH and then the line from the BH goes to the 3pt, no tank line. The main system relief is in the loader valve.

 

[GPintheMitten]

Where you put additional valves does not matter if you follow the PB to IN of the next valve.

With all valves in neutral, the flow passes through all valves to tank.

All return lines go to tank.

Some BH configuration send the return hose directly to tank, by passing the 3pt.

The BH return hose should never go to the 3pt.

If the BH has three hoses, then the PB from that valve goes to the 3pt and the return hose goes to tank.

My BH65 backhoe has only 2 hoses. When the hoe is not on, the hose from the loader PB is connected to the 3pt via QD's. When the hoe is on, I separate those QD's and connect them to the QD's on the hoe, so that the hoe is in between the loader and 3pt.

 

[GPintheMitten]

Yup, that's how I did mine, the feed line for the backhoe comes off my rear remote valves.

OK, thanks. Now regarding return to tank -- do the rear remote valves have a return to tank line that needs to be plumbed? If so, how did you plumb yours? Also, got any pics?