FEL Valve assembly issue - DIY or shop?

[true temper]

Since pressure and flow is generated by the pump, I disagree!
As you idle up, you will see a vast increase in flow and to a lesser degree some pressure increase. The only other time that pressure increases is a restriction of some type. This restriction could be going to a designed reduction of flow—large suction to smaller pressure hose/line. The only way a valve operating changes pressure is if it restricts the flow—going from a larger port to a smaller port.

Coy I have no idea what in the world you are thinking???
Lou has it right.

 

[CoyPatton]

Coy I have no idea what in the world you are thinking???
Lou has it right.

So you guys have no flow to your valves until you operate them and then have to wait for pressure to build. Also you gave no need for a pump since it does not spin with the engine?

Not sure what koolaide you guys drink, but keep it to yourselves!

My pump turns ad the engine does. It produces flow as it produces pressure. Yes you can increase pressure, but to claim no pressure when pump spins is a total failure to understand the concept of a pump!

 

[rangerfredbob]

The hydraulic pump produces flow, yes, but that does not mean there is a pressure on the outlet. The pump can produce pressure and will if there is a restriction to flow. The pump is a constant volume flow per revolution, in a hydraulic control valve until a valve is moved is constantly just returning to the reservoir and the only pressure is from the restriction in flow through the system. Once the valve is operated the hydraulic flow is diverted from the normal bypass to the cylinders, once the return is restricted now the constant volume is pushing against the load on the cylinders creating pressure. There is not a constant pressure in the hoses out of the hydraulic pump in idle operation...

You might understand the concept of the pump, but doesn't sound like you get the concept of flow and pressure. If you wave your hand out in thin air it doesn't take any force yet your hand is moving, if your hand hits a wall while you are waving you are exerting pressure against the wall, same deal here... It's easy to miss, believe me...

 

[rangerfredbob]

Another way to think about it is an air compressor, if you have nothing connected to the outlet when you turn it on there is no pressure on the gauge as the compressor is circulating atmospheric air back to the atmosphere, there is flow but no pressure. If you create a resistance by connecting an air tool or blocked off tank there is now pressure on the outlet of the compressor.

 

[CoyPatton]

The hydraulic pump produces flow, yes, but that does not mean there is a pressure on the outlet. The pump can produce pressure and will if there is a restriction to flow. The pump is a constant volume flow per revolution, in a hydraulic control valve until a valve is moved is constantly just returning to the reservoir and the only pressure is from the restriction in flow through the system. Once the valve is operated the hydraulic flow is diverted from the normal bypass to the cylinders, once the return is restricted now the constant volume is pushing against the load on the cylinders creating pressure. There is not a constant pressure in the hoses out of the hydraulic pump in idle operation...

You might understand the concept of the pump, but doesn't sound like you get the concept of flow and pressure. If you wave your hand out in thin air it doesn't take any force yet your hand is moving, if your hand hits a wall while you are waving you are exerting pressure against the wall, same deal here... It's easy to miss, believe me...

Wrong! Without pressure there is no flow!
You fail to comprehend the basic principles of fluid flow!
Test it out! Cut your rubber line into. Hold it above the pump level. If no pressure it will only ooze out. With pressure it will flow in a stream!

 

[CoyPatton]

Another way to think about it is an air compressor, if you have nothing connected to the outlet when you turn it on there is no pressure on the gauge as the compressor is circulating atmospheric air back to the atmosphere, there is flow but no pressure. If you create a resistance by connecting an air tool or blocked off tank there is now pressure on the outlet of the compressor.

Put your finger/hand over that outlet (don’t block it) and then tell me there is no pressure! If you can feel any air movement (any you will if close) how does that happen if it is the same pressure?
Be for real, go back and drag out your Jr. High science book! That atmospheric air you claim has no pressure actually has pressure! It changes with storms, weather fronts, altitude.
Such just good old fashion down hill water flow is a form of pressure!
Worse you use the word compressor and claim no pressure! If no pressure, you probably have a bad head gasket for if it has compression it has pressure.

 

[ptsg]

Coy, it's not the first time you come up with this theory. You've been proven wrong several times, yet you still insist on that...

Please, take some time and go read about open center hydraulic systems. It's actually such a simple concept.

 

[K5lwq]

Wrong! Without pressure there is no flow!
You fail to comprehend the basic principles of fluid flow!
Test it out! Cut your rubber line into. Hold it above the pump level. If no pressure it will only ooze out. With pressure it will flow in a stream!

So without flow is there pressure?

Tee a pressure gauge on the power in port for your loader valve. What does it read before opening the valve to a cylinder? Then what does it read as the cylinder is moving? Then what does it read when it reaches full travel?

 

[Leejohn]

Should be saying very low psi.

 

[rangerfredbob]

Put your finger/hand over that outlet (don’t block it) and then tell me there is no pressure! (snip)

That creates a restriction which creates a resistance in flow which is near the definition of pressure... Yes the atmosphere has pressure, roughly 14.7 PSI or 100kPa on average around sea level, but what most people refer to and what gauges read is "gauge pressure" which is the pressure above the current atmosphere where the operator is. We could go over differential pressure, absolute pressure or whatever you want, but there has to be a restriction to flow for a pressure differential to exist...

I have a mechanical engineering degree and have been calibrating engines as well as troubleshooting engines and fuel systems for 15 years. I will never claim to know everything and am wrong on occasion...

You can have flow without pressure, but you cannot have pressure without flow (unless in a static condition). Pour a bucket of water out on the ground, there is no differential pressure in that condition (the water is just surrounded by atmospheric air in all directions, the only pressure would be gravity acting on the height difference from the bucket to the ground), but there is flow...