4430 hydraulic issue

[Woodbridge]

I had a pinhole leak in the steel supply line 16b in the picture. I replaced it with a hyd hose and after a couple hours cutting hay the elbow blew off the transmission case, blowing the valve and spring all the way out onto the ground. I figured maybe the hose was allowing some movement and somehow the keeper came undone, so I went back with a new steel line and the elbow blew off again at startup. I can’t see any damage on the keeper, the elbow, or the keeper groove. When I put the pieces together in the shop they seem to be solidly connected. I have the valves, spring, and spacer in just like the picture shows and they arent bound up that I can tell. i put all new orings in when I reattached it. I did something wrong but I can’t figure out what it was. The keeper itself isn’t expensive so I thought that might be my next step, but like I said it looks fine. Any ideas?

 

[Tx Jim]

1st thing I suggest after installing new line/fittings is check frt pump stand-by pressure which should not be over 2350 psi.

 

[Woodbridge]

But doesnt the internal pump pressurize the supply side?

 

[Woodbridge]

I’m not very bright about hydraulics unfortunately. What can I rig up to supply oil to the front pump so I can test the standby pressure? Forgive my ignorance if I’m asking stupid questions.

 

[Woodbridge]

Okay. My brain maybe tracking now. The pressure blowing off my elbow is not from the transmission it’s back pressure from the front pump. So either the front pump standby pressure is too high or the pressure control valve that I put back together is not functioning properly. Is there a way I can lower the pressure on the pump so that I can get the piping to stay on while I start the tractor and figure out what’s wrong?

 

[Tx Jim]

On bottom of frt hyd pump one can loosen lock nut on stroke control valve & turn adjusting screw counter clock wise a round or 2 to lower pressure. I think pressure control valve malfunction will not cause a hyd line/hose to fail. Stroke control valve malfunction causing extreme pressure can cause hyd com[ponents to fail

 

[grwrench]

hello,, you can buy the elbow assembly, there is a snap ring inside the elbow that holds it together, some thing must be defective for it to blow apart, i have been working on these for 50 years and never saw one blow apart..

 

[Cliff Nelson]

Replace the elbow assembly with a new one. They wear from vibration over time and leak or come apart. The snap ring groove is likely rolled so it won't hold the pressure anymore. You can check standby pressure at the remote outlets. Pressure control valve shuts down oil to the rockshaft and remotes if pressure drops below 1800 psi (plus or minus) in order to maintain pressure to steering and brakes.