I recently added a dump body manufactured by Perfection-Cobey to my 88' International 1900. The truck has a central hydraulic system that powers an old school Frink plow and wing setup. What I thought would be a simple swap has taken a bit of a turn when I went to do the plumbing.....The valve available to operate the the dump body has two 3/4" lines. Seemed obvious enough that one was for pressure to lift and the other would be for the return. Problem arises when after I installed the 3/4" supply, I find the return line from the dump cylinder is a "low pressure" 1-1/4" line. With a few adapters I was able to reduce the line to enable me to complete the connections. Figuring that I'm a genius by solving the problem it's time for a test.....Hopped in the cab, fired it up, and operated the handle to raise the bed, annnd, NOTHING! Thought it might be airbound. Found a plug at the top of the cylinder and operated the handle again until oil bubbled from the opening. Replaced the plug, operated the handle to lift the body and still no action.... Moved the handle to lower the body, just to see what might happen, and BOOM! The "reduced" 1-1/4" line blows off the cylinder and hydraulic oil is everywhere! Do I have the wrong cylinder? Wrong valve? I've got no idea (obviously...) what's compatible and what's not. Could use a little help here Thanks in advance.
How about a picture of the cylinder? A motor has a return line, a cylinder will have an extend and retract function, unless it just extends under power and retracts by gravity, hence the picture.
The first problem is you have a single acting cylinder designed to act as the oil reservoir as well, connected to a double acting valve. You need to connect the second valve port to a tank return effectively making the valve work for a single acting cylinder. Also the low pressure line from the top of the cylinder, connect it to a tank return port if possible as close to the top of your hydraulic tank as you can get, it's just for leakoff the way your hydraulic system is set up. I also think the piston seals in your cylinder are bad and/or your valve is not supplying much oil for the lift function. The only way you can get oil bubbling up at the top of the cylinder is if the oil is bypassing the piston.
Never mind. lantraxco figured it out.
Maybe, maybe not. Best guess, based on limited experience with old farm dumps. I'm with you, pictures are needed.