hayden
Veteran Member
Does the cylinder compress and then spring back, or does is slowly lose it's position and then requires use of the control lever to return it to the original position?
If it compresses and then springs back once the load is removed, it's almost certainly air trapped in the cylinder. The air compresses under load, then springs back when the load is removed.
If the cylinder shifts position under load, but requires use of the control levers to restor position then there is leakage or bypass in either the cylinder or valve.
The check valves being described I always thought were to prevent momentary sagging at the instant you engage the control lever to move the cylinder. I didn't think they had any effect if the lever was in a stationary position. That said, I'm not an expert.
To get air out, disconnect the cylinder end and run it through several full extend/retract cycles. Usually this will get the air out. If not, the positioning of the hoses adn cyl tip angle may be causeing air to get trapped at some intermediate high point in the cylinder or hose. Temporarily repositioning the cylinder/hoses so that any air has an upward path back to the control valve may help trapped air escape.
The only other thing I can think of, and it seems unlikely, is that one of your hoses is defective and is able to expand under pressure. The ballooning effect would behave much like air trapped in the cylinder.
If it compresses and then springs back once the load is removed, it's almost certainly air trapped in the cylinder. The air compresses under load, then springs back when the load is removed.
If the cylinder shifts position under load, but requires use of the control levers to restor position then there is leakage or bypass in either the cylinder or valve.
The check valves being described I always thought were to prevent momentary sagging at the instant you engage the control lever to move the cylinder. I didn't think they had any effect if the lever was in a stationary position. That said, I'm not an expert.
To get air out, disconnect the cylinder end and run it through several full extend/retract cycles. Usually this will get the air out. If not, the positioning of the hoses adn cyl tip angle may be causeing air to get trapped at some intermediate high point in the cylinder or hose. Temporarily repositioning the cylinder/hoses so that any air has an upward path back to the control valve may help trapped air escape.
The only other thing I can think of, and it seems unlikely, is that one of your hoses is defective and is able to expand under pressure. The ballooning effect would behave much like air trapped in the cylinder.