Case 300 hydraulic problem

DKase

Well-known Member
Working on a 310 that we are raising from the dead. Eagle hitch lifts just fine, but will not
lower. I can push down on the eagle hitch arms with the valve in the lowering position till the
front axle raises up, but the eagle hitch will not lower. Cracked the hydraulic line to the valve
to let the oil out, and it goes down just fine. Where do I dig into the valve to find the load
check? If the check is not stuck, where do I look next?
 
Check the linkage at the control valve, make sure the spool is making full travel.

If that is not it, the plunger in the interlock may not be moving to the return position.

This how the single acting interlock works for the Eagle Hitch:

Pic 1 When the lever is moved to the raise position pump pressure enters port "A", pushes the spool to your right, unseats the ball check and pressure continues out to lift the EH piston via port "AA". Ports "B" & "C" are inactive and "BB" is plugged. When the lever is moved back to neutral the spring seats the ball check and the EH piston is in a hydraulic lock.

Pic 2. When the lever is moved to the lowering position, pump pressure enters port "B" pushes the spool to the left, unseating the ball check and providing a path through port "C" for pump circulation. The piston oil returns to the system via the ball check and port "A".

The number of copper gaskets under the end cap adjusts the spool travel to regulate the amount of oil passing through port "C", size of the ball check opening and so the descending rate of the draft arms.

Joe
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Thanks, that is exactly what I am looking for. If I read this right the load check cannot be stuck because the pressurized oil must unseat the load check to allow the oil to the eagle hitch on the raise position. Almost has to be a problem with the valve not moving far enough to unseat the valve.
 

The roll pin that holds the control lever to the shaft at the control valve is most likely broken and will have to be replaced.
 
Per L.Fure roll pin can be a problem although I have only seen them severely worn along with the bores. Pic 1 is the control valve fully stroked but I am no longer sure which direction the pic shows.

While your in there, check that your interlock is not installed end for end (an all too frequent occurrence for some reason) Note the different gaps between the bolt heads and fittings relative to the front of the tractor. If installed incorrectly, it will still function but internal oil passages will be restricted some and port "C" will be blocked causing the pump relief valve to lift when lowering the hitch.

Joe
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