Thumb Valve Leak Mystery

[J_J]

Did you use the PB port on the thumb valve to feed the BH?

The Thumb OUT port should go to tank.

 

[wdchyd]

Regarding the perpetual leaks that the OP'r is running into, there is an elevated return pressure downstream of this valve......it needs to be a power beyond type valve to deliver downstream pressure to the next valve, separate from return to tank flow.....

the orings on his valve and the oring in the PRV cartridge is seeing the high pressure from a restriction or the next valve inline.....resulting in oring failure every time......these orings are not suppose to see high pressure, only low pressure from return flows to tank......

NEEDS PB VALVE......

I stand by my original reply.........:thumbsup:

This mess could have all been avoided had the dealer used PB to power the BH valve (next in line) and added an extra return line back to tank.....

Maybe this valve can be converted, if not the OP'r will have to change this out to a PB valve.......

One of the other problems with running two valves in series is "Series resistance adds pressure", it's a dangerous situation to run both valves together to full relief setting.......the valve was never hooked up properly from the get go......and even if the BH valve was run on it's own separately the back pressure is still too great for the thumb valve......

 

[wdchyd]

I just realized this setup is on a new tractor .......time to visit the dealer and give them a hydraulic lesson......Then let them fix it right......:confused2:

 

[mmranch]

The dealer installed the both the original Salami thumb valve (which I don't think had a PB port) and the Prince RD4100 thumb valve.

The Prince RD4100 has a PB port option... but it is currently plugged with the plug option (you can see the plugged port in the side view of the console). The Output port is feeding the BH control valve input port.

Sounds like the RD4100 PB option needs to be installed, then PB feeds the BH input port. The RD4100 Output port then needs to be routed to T into the return line (I could just T it into the return line right?). Why does the return line have that pressure reducer looking thing on it? Shouldn't the pressure already be reduced when it comes out of the BH valve?

I'll have to talk with the dealer about the plumbing setup.

Thanks again.

 

[wdchyd]

Sounds like the RD4100 PB option needs to be installed, then PB feeds the BH input port. The RD4100 Output port then needs to be routed to T into the return line (I could just T it into the return line right?). Why does the return line have that pressure reducer looking thing on it? Shouldn't the pressure already be reduced when it comes out of the BH valve?

You are on the right track, PB NEEDS to be used in this application....can you get a pic of the "pressure reducer looking thing"......

I know there is has been some big arguements here on TBN against PB but this is just one example where lack of PB has caused lots of grief......

 

[mmranch]

Here's the pressure reducer thing on the BH valve output line in the picture.

 

[wdchyd]

Not sure what that is.......maybe a check valve to alleviate problems from hooking up hoses to BH backwards..??....:confused3:.....or just to tame an inrush of return oil to keep from backing up into BH valve..(just a guess)....

if it doesn't show in your original literature, you can remove it and test with air pressure to see if it's a check valve or restrictor valve

 

[J_J]

Here's the pressure reducer thing on the BH valve output line in the picture.

How do you know it is a pressure reducer? Did you measure the pressure before and afterward the fitting

 

[mmranch]

Thanks for the ideas! I don't know that it's a pressure reducer... just thought I saw one on the SurplusCenter website that looked like that. But I just perused the website again and now I can't find it. But I did find a number of check valves that looked like that so it's probably a check valve.

 

[wdchyd]

Some manufacturers will use them in case the hoses are reversed accidentally....ironically to prevent pressure building up in the return side of the valve so the orings on the spools don't blow out....

Sound familiar..??