Hydraulic Spool and Cylinder Question

[capekubota]

I have a single spool hydraulic valve and cylinder to lift the B2551 snowblower on my tractor. When I first installed it, the lever action seemed wrong to me. To lift the blower, you had to push lever forward. To lower it, you had to pull the lever back. Thats the opposite of what I was used to....So I went ahead and switched the hydraulic lines on the cylinder, so that now, pull lever back, blower goes up, and forward it goes down.

Now I am running into an issue where I am getting air bubbles and overflowing of hydraulic fluid through breather. I want to eliminate the change I made above as being the issue. (I also repaired an issue with 3 pnt hitch, so that may be culprit).

So do you think that hose change could cause issues? I have attached a parts pic of cylinder and spool valve..

 

[eserv]

The only place air can get into the system is from the transmission case to the hydraulic pump on the suction side. did you remove the screen and damage an oring?

 

[North Idaho Wolfman]

All of what you changed is in the pressure side of the system, In order to introduce air into the system, you would need to have a leak on the suction side of the system, not the pressure side.

 

[Kennyd4110]

This is a single acting cylinder on the plow? Just one hose going to it?

 

[capekubota]

It has two hoses going to the cylinder, dual action. The 3pnt hitch was leaking down so I replaced the seals on the cylinder.

I did notice tonight that the large suction metal line, that runs from trans (tank) to the hydraulic pump (which I assume is the suction side) has a rubber hose connection at the pump end, held on by hose clamps. Thats where i will start looking for leaks.

 

[Dave_eng]

No to hose change. Perhaps too much fluid in tractor.

Where does the pressure for the blower control valve come from? Does it have a power beyond port feeding the 3 pt?

How many hoses connect to your control valve?

If you have a system where the relief valve is constantly relieving pressure because of a hydraulic plumbing error this will aerate the oil.

Provide more history of the blower's installation unto the tractor from a hydraulics point of view.

On a point unrelated to your concern, often the control valves for a front mounted blower have a float position to avoid loosing steering by the blower lifting the front wheels all the time.

The float position is usually reached by pushing the control lever far forward past a resistance in the valve.

The idea of the float position is to allow the blower to move up and down over changes in ground contour.

On pickup trucks with front plows, the lift cylinder is only single acting and is connected to the cylinder with a chain so the blade can move up and down on its own.

The 3 pt hitch is an example of where you cannot apply any down pressure.

Dave