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Date: Sun, 11 Nov 2007 19:03:45 -0500
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From:  <lhenney@charter.net>
Subject: Hyd Chirp - Case Closed?
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Chris,

I've been out for too many days but wanted to thank  you on the detail presented in your post.  I've probably been wrong all along about my seapage to low pressure switch set.  This is of course not with certainty because I do not have pressure gauges but your timing, twitch, blink, freeze discription is what I see. Although frequently I don't see anything, it's just quiet.  Crack dump, issue resolved.

Anyway, the weight of wheels hurrying fluid back to pump theory was something I'd had no inkling of a thought about  (and poppet valves, either for that matter).  Along the lines of Randy Snarr's comments however, I think what I'm hearing is, "that's just the way it is".  Do you agee?  Therefore, the only reasonable solution would be to locktight the nut on the dump valve handle?  Handle falling off would be the only real failure mode?  I'm not completely satisfied.  I say this because for a couple hundred hours, perhaps before I reversed my spool valve, my pump did not do this.  Perhaps another rebuild is in order.  

One clarification?  At the moment that the pump hangs because of low pressure fluid rush pinning poppet valve, is the pump mechanically inhibited?  Why is it not grinding away?  Or is the low pressure switch set?  Again, I'm sorry to ask but am a no gauge guy at present.

Scott brings up a good goo point.  That is, 5606 is probably not gumming up the works as it is not in contact with air.  However, I mounted my switch vertically on a 1" leg perhaps this leg does have air in it and contributes to stickiness in the switch.

I guess I could easily wire my ohm meter to read across the low pressure switch and see with certainty whats happening.

Hose Expansion?  I'm having trouble figuring where any of that discussion is going because I thought the 5606 is relatively imcompressible.  If the fluid is incompressible then the relative expansion of the hoses would not change while cruising.  No?  

Do you see any merit to a three way dump valve connecting  both high and low to the 3rd pump center input?  Would this provide a higher safety margin?

Gauges:  Anyone got a good gauge recommendation?  I'm guess'n McMaster-Carr or WW Granger? (of course "good" in this context is meant to be functional, cheap, and buryable out of sight except while troubleshooting).

Larry Henney
N360LH
Still more  impressed with high tail winds than book stacks.