What I would look for next is what happens when you give the steering wheel a slight "crowd" in either direction with wheels fully engaged with the ground.
What I would expect is pump pressure would rise as the spool moves and forces the boost/assist cylinder to move, then as the spool re-centers, the pump pressure would then drop back to zero (open-center/spool-neutral condition).
Another mental abstraction to think about (or from the viewpoint of) is that the system doesn't exactly "demand" pressure in my thinking. In retrospect, it "creates" backpressure (what the pump-output gauge is reading) by virtue of creating an effective restriction to fluid flow or presenting the ever-adding positive-displacement volume of fluid against a mechanical load (as in the case of a hydraulic cylinder).
Just a practical example of above, with a functioning system I would fully expect pump backpressure to be significantly lower when turning the tires on a film of slick mud vs. when they are half-buried up to the axles. In other words, even though the pump can produce 1400psi when thoroughly dead-headed, the pressure is "matched" to the mechanical "resistance" load applied in the opposite direction.
This post was edited by mattofvinings at 16:41:34 06/20/09 3 times.
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Today's Featured Article - Identifying Tractor Noises - by Curtis Von Fange. Listening To Your Tractor : Part 3 - In this series we are continuing to learn the fine art of listening to our tractor in hopes of keeping it running longer. One particularly important facet is to hear and identify the particular noises that our
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