I'm wanting to add a Top N Tilt type system to my tractor. I see where everyone always recommends using the cylinders with the "double piloted check valves." Can anyone explain how these work? It seems to me if you have a check valve in-line, then you are defeating the purpose of a dual acting cylinder. Is the "drift" really that bad without the check valves? Anyone out there that uses this set up? Any info would be appreciated.
Top N Tilt Cylinders
- Thread starter N9PDL
- Start date
Henro
Super Member
- Joined
- Jul 4, 2003
- Messages
- 5,977
- Location
- Few miles north of Pgh, PA
- Tractor
- Kubota B2910, BX2200, KX41-2V mini EX
Control valves are not perfect...they can leak through when centered. If they leak through, the cylinder connected to them will move. Whatever is connected to the cylinder will move. If you want whatever is connected to the cylinder to stay where your put it, you need check valves somewhere between the control valve and the cylinder.
There are two places where check valves are common. Either at the cylinder itself, or attached to the control valve.
Either will work effectively well, but the ones at the valve are better if safety is a concern, because if the check valves are at the control valve, there is a hose to worry about between the control valve and the cylinder. If the hose should fail, the cylinder will move. If the check valves are at the cylinder, the hose is not an issue.
Pilot operated check valve just means that the hydraulic pressure when applied opens one of the check valves. It is the nature of a check valve that it just passes fluid in one direction. With a pilot operated check valve, if the fluid tends to close the check valve on one side, it is countered by the hydraulic pressure applied, and when hydraulic pressure is applied the system works like there was no check valve there at all.
But when system pressure is not applied, the check valves work to lock the cylinder in place.
Pilot operated check valves really have no relationship to the way a double acting cylinder operates. All they do is hold that cylinder in position after the control valve is centered. If the PO check valves were on the cylinder, you could remove a hose and the cylinder would hold position.
Drift without PO check valves? Nothing to a lot. All depends on your particular control valve and how much it leaks. Don't go by any one person's experience, because you will not have his valve on your tractor.
Hope this helps... /forums/images/graemlins/smile.gif
There are two places where check valves are common. Either at the cylinder itself, or attached to the control valve.
Either will work effectively well, but the ones at the valve are better if safety is a concern, because if the check valves are at the control valve, there is a hose to worry about between the control valve and the cylinder. If the hose should fail, the cylinder will move. If the check valves are at the cylinder, the hose is not an issue.
Pilot operated check valve just means that the hydraulic pressure when applied opens one of the check valves. It is the nature of a check valve that it just passes fluid in one direction. With a pilot operated check valve, if the fluid tends to close the check valve on one side, it is countered by the hydraulic pressure applied, and when hydraulic pressure is applied the system works like there was no check valve there at all.
But when system pressure is not applied, the check valves work to lock the cylinder in place.
Pilot operated check valves really have no relationship to the way a double acting cylinder operates. All they do is hold that cylinder in position after the control valve is centered. If the PO check valves were on the cylinder, you could remove a hose and the cylinder would hold position.
Drift without PO check valves? Nothing to a lot. All depends on your particular control valve and how much it leaks. Don't go by any one person's experience, because you will not have his valve on your tractor.
Hope this helps... /forums/images/graemlins/smile.gif
PineRidge
Super Member
I think it would be safe to say that if you can afford a cylinder with a double piloted check valve that you will be less likely to be replacing it because you are not happy with the drift problem at a later date.
Pay me now or pay me later kinda thing.
Pay me now or pay me later kinda thing.