Case 311 front bucket hydraulics

bicklebok

Member
I have a 1956 Case 311 thats fitted with a front bucket. When I try to lift the bucket it will raise approximately 4' in the air, then one of the cylinders freezes while the other cylinder continues to try and raise the bucket. This causes the bucket to lift farther on one side and stress the metal.

I have checked the hydraulic fluid and it's full.

If my memory is correct, it seems the hydraulic set up for this tractor is a little different than modern day tractors.

Any ideas on what's causing this and what I can check??

Thank you!
 
The early loader for 311 was a case model 291 with SA lift cylinders and DA bucket cylinder(s).

Pic is original hydraulic setup using a selector valve to direct hydraulic pressure supply to the Eagle hitch OR the loader lift cylinders. There are several ways to modify this hydraulic circuit but this is original installation.
cvphoto3658.jpg


If in fact you have SA lift cylinders there will be one hydraulic line to the bottom of the cylinder for both supply and return (see pic). The top of the cylinder will have an open vent hole. When lift pressure is admitted to the piston side of the cylinder the air space on the rod side of the cylinder is relieved via the vent hole.

If the vent hole is plugged the air pressure will build up on the rod side of the cylinder and when that air pressure equals the incoming hydraulic pressure the lift cylinder is in irons just as it would be if it was fully raised.

This situation may occur when there is a minor oil leak pass the piston seals into the rod side that will push out the vent hole when the cylinder is fully raised making a mess. Vent holes are usually threaded so it gets plugged to eliminate the oil mess. Initially the lift cylinder will travel to near full height but as the oil leak pass the piston seals is progressive and the rod side air space is compressed as it is displaced with the leaking oil and the lift height if the cylinder is gradually reduced.

That is just my take on it having worked on many hydraulic systems that "quick fixed" by amateurs.

Joe
 
Wow, you know your hydraulics! That looks like the system I have.

Being I have limited knowledge of tractor hydraulics, what would be my first troubleshooting step? Check that the vent release is not blocked?

I do remember hydraulic fluid used to squirt out of my cylinder a few years ago when I would raise the bucket up high, but I dont remember if it was the cylinder thats currently giving problems or the other side.

Thank you!
 
Check that the vent is clear. Vents often have a plug that is drilled to vent the cylinder but in a manner to prevent the entrance of rain water. Another very remote possibility is a severely bent rod that is binding in the end packing, if so there is usually an indication of chrome wear on one side of the rod.

Joe
 

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