Rear Remotes (again)

[BlacknTan]

I've got everything to install my rear remotes. The only thing I have a question on is plumbing.
First, I've got a Kubota B-7800 with FEL.
I've read here many times that the hose from the loader valve PB port to the hydraulic block should be removed. A hose then goes from the PB port on the loader valve to the input on the remote valve. a hose then goes from the PB port on the remote valve back to the hydraulic block where the hose previously removed went. Then, a hose goes from the output port of the rear remote valve back to the tank..
In picking the mechanic's brain at my kubota dealer, he said that is unnecessary. He said he merely removes the hose from the loader valve PB to hydraulic block, and then runs a hose from the PB on the loader valve to inlet of the remote valve, and runs another hose from the outlet of the remote valve back to the hydraulic block (return).. A simple loop. He said that he has been installing rear remotes this way for 27 years.

A hydraulic expert at Cross MFG, the remote valve manufacturer confirmed the mechanics thoughts.
Why are all the remotes at TBN plumbed with the three hoses as in the first method as opposed to the mechanic's second method??

Are there advantages of one methos over the other??

What am I missing??

 

[BlacknTan]

Thanks for all the help...

 

[Rara Avis]

Thanks for all the help...

 

[BlacknTan]

I'm sorry.

After 115 views, I thought that someone knowledgable on hydraulics could tell me if one method was better than the other, or if both would work equally well.
I realize that this topic has been discussed many times, and i've done my homework by reading most of those threads, but my question has never been discussed that I could find.

I thought that possibly someone here could help... Maybe not.

 

[Ductape]

I wish i could be of more help...... but i can tell you my backhoe is plumbed with just two hoses like you have suggested. Power beyond out of the loader valve back to the hoe..... return from the hoe back up front to the hydraulic block where the power beyond used to connect. No third line to the sump....

 

[Lasgambler]

What ever you are missing, I am too. I don't have alot of experiance in hydraulic plumbing.
I have a Cross triple spool valve and it is plumbed the "Simple Loop" way you describe. Good Luck.

 

[BlacknTan]

Thanks for your help, gentlemen.

Your posts are confirming my suspicions that, since there will never be another valve installed downstream, that the 2 hose method is the way to go.

Thanks again for the replies.

 

[Farmerford]

If your valve tank port connects to the inlet port of the three point hitch the hydraulic fluid flowing through the valve powers the TPH as well. If so, when the TPH lifts an implement, the fluid pressure needed to move the implement will also be present in the tank/outlet section of the valve. Many valves have much lower pressure ratings on the tank section than on the inlet section, and are designed to be used as the last valve in a series where there are no downstream devices (cylinder, motor, etc.) to put sigificant back pressue on the tank section of the valve.

If these pressure limits are exceeded the o-ring seals at each end of the spool which keep fluid from leaking out between the valve block and the spool can be damaged, causing the valve to leak. The valve manufacturer should be able to tell you the pressure rating for the tank section of the valve. It is typically 500 psi.

If you lift a heavy implement at high engine rpm so that the pump develops maximum pressure, that pressure in the outlet circuit of the valve could damage the o-rings. A PB valve avoids this by having a separate high pressure line (PB) for the high pressure fluid going to the next valve and a separate low pressure return line to the tank.

 

[wmgeorge]

I've got everything to install my rear remotes. The only thing I have a question on is plumbing.
First, I've got a Kubota B-7800 with FEL.
I've read here many times that the hose from the loader valve PB port to the hydraulic block should be removed. A hose then goes from the PB port on the loader valve to the input on the remote valve. a hose then goes from the PB port on the remote valve back to the hydraulic block where the hose previously removed went. Then, a hose goes from the output port of the rear remote valve back to the tank..
In picking the mechanic's brain at my kubota dealer, he said that is unnecessary. He said he merely removes the hose from the loader valve PB to hydraulic block, and then runs a hose from the PB on the loader valve to inlet of the remote valve, and runs another hose from the outlet of the remote valve back to the hydraulic block (return).. A simple loop. He said that he has been installing rear remotes this way for 27 years.

A hydraulic expert at Cross MFG, the remote valve manufacturer confirmed the mechanics thoughts.
Why are all the remotes at TBN plumbed with the three hoses as in the first method as opposed to the mechanic's second method??

Are there advantages of one methos over the other??

What am I missing??

When I added my Hyd remotes to my old JD650 nobody could really help me, even at the dealer . I ended up tracing it out more than once and coming back here to do searches. I don't know how you get by without the tank return??? It would seem to me that to release pressure on a cylinder it needs to go someplace??

When I got mine all figured out, I drew it out in AutoCAD in color, made it easy to pipe up.

 

[BlacknTan]

The mechanic at the Kubota dealer said he's been plumbing them with 2 hoses for 27 years with no issues.. I can't tell him he's wrong.. He knows a helluva lot more about a Kubota hydraulic system than I do...
I went to another Kubota dealer and asked another mechanic the same question. I got kind of a blank stare, and he wrote me down the phone number of a local hydraulics shop.

I'm pretty well committed to a 3 hose system at this point, with one hose teed to the tank...

If I blow up my pump, I'll take pictures of the carnage and post 'em....