Oil Recirculation in closed loop system

[SpringHollow]

SpringHollow

You said. [ For a given turning direction, the two supply (extend) lines are tied together. ]

Actually, One cyl extends and one cyl retract and are teed together.

If all the steerings circuit for the PT are identical, go back and look at the pictorial on post 21.

It is clearly laid out .

True, i had the function switched on the one cylinder but the principle is the same.

Ken

 

[MossRoad]

If you push fluid into one side of a cyl, the fluid on the other side moves out or returns to tank.

And there's where you are mistaken. When you push the fluid into one side of this steering cylinder the fluid on the other side moves into the other steering cylinder, not the tank.

 

[J_J]

If I put fluid into the base end of cyl 1 and put fluid into the rod side of cyl 2, both cyl will operate , with one pushing and the other pulling.

At the same time, fluid is leaving the other side of cyl 1 and other side of cyl 2.

Why don't you go out to your machine and tell me what fluid is where, and how much.

Will you look at the diagram you posted and tell me why there is a return hose from the steering valve to tank.

Tell me again about no fluid on the other side of the piston.

Just ain't gonna happen.

If I turn the steering about half way, will there be fluid on both sides of the piston.

If I am mistaken, so be it, but I don't think so.

By the way, what is the purpose of the tank return line from the steering valve?

Think about it, even the power steering in your car sends the used fluid to tank.

The steering cyl gets new fluid every time you turn the wheel. Does not matter which way you turn.

 

[MossRoad]

Here's the circuit with the left rod extended and the right rod retracted.

 

[MossRoad]

Here's the circuit showing the same thing with fluid in the base of the left cylinder.
View attachment 423756

 

[MossRoad]

If I push that left rod in, where's the majority of the fluid going to go?

 

[MossRoad]

Its going to go into the top of the right cylinder...
View attachment 423759

 

[MossRoad]

Yes, the bottom of the cylinder contains more volume than the top of the other cylinder. I know that. The point is, the majority of the fluid just gets shoved back and forth between the two sides of the opposite cylinders. If the oil is getting exchanged completely, why is the oil in the cylinders discolored when the oil in the tank is not? It should be the same color.

And I know I'm sounding pissy, but I'm not trying to. I wish we were all sitting in a room together with some beers, some cylinders, some hoses and some pumps and having a good laugh about this. Typing does not show facial expression or mood. To me, its a discussion, not an argument.

 

[SpringHollow]

Moss,

If you trace the two vertical lines, one goes to the pump via the valve. The other goes to the tank via the valve.

In a hydraulic cylinder circuit, pressure determines the amount of force you can overcome and flow determines the speed and magnitude of movement. If there is no (or minute) flow to the tank or the return of the pump, then there is no real movement. You are saying no flow to the return of the pump/tank so there can only be minimal movement of the cylinders.

Flip the right cylinder 180° leaving the hose connections as is. If you now mechanically connected those two cylinders as is to your FEL, it would work appropriately except because the rod end are switched, the cylinders would not have equal maximum force.

In this case, I am afraid that everything I know about physics as applied to hydraulics says you are not thinking about this correctly. Doesn't mean that I am not missing something because I am quite capable of having a brain fart but in this instance I do not think I am. If I thought there was an even 1% chance I was wrong on this, I would ask in the hydraulics forum.

Ken

 

[MossRoad]

Or is the schematic this way, which would make more sense?