X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 09 Apr 2010 16:53:14 -0400 Message-ID: X-Original-Return-Path: Received: from web111404.mail.gq1.yahoo.com ([67.195.15.150] verified) by logan.com (CommuniGate Pro SMTP 5.3.5) with SMTP id 4215073 for lml@lancaironline.net; Thu, 08 Apr 2010 22:15:57 -0400 Received-SPF: none receiver=logan.com; client-ip=67.195.15.150; envelope-from=randylsnarr@yahoo.com Received: (qmail 88308 invoked by uid 60001); 9 Apr 2010 02:15:22 -0000 DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:X-YMail-OSG:Received:X-Mailer:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=pGVk+9lGxS/xeO44Pg7tL4Lw0pBXn3dz4QoeY3EiKFp0ZMRsTVxPaUr3f/VZ0Qmpu4cJiKVFS2gbB/BJNRSKQRMsOxs4JYTO67Ukdbrw06431N8Y6IBReifj0A91l6vDaoLsBt6hZCwM53xPqwOfPV/o7QZzkekdrY+Ngwgc8Lk=; X-Original-Message-ID: <977494.87432.qm@web111404.mail.gq1.yahoo.com> X-YMail-OSG: LfQEKf4VM1lXuwBjZZWsu5BCkKODYZJ3lMp0V8teR1OcGSf UW3WTtz9a246P_tQvJAe8EKDQwAeNtfYtoTOxv8rZlz4Wj8KLArUeS0up0kO YmRCbzxx4SZ9GPDk_4InbdWsh91N8apnBOvYlShmJ9OshdSgBo6K0.OIm07K Bi6rS2.Ih9wWgUnuXUSx6w.KfV90cIQuSD9HDotr15wDWV1zhYXREXdZXVxI QbhwcSghYBQNAdeoRY9hGp3VwuD9_W4XVDkkhQybQOeuF3xCr5HIMP5XvKDE Y_3r67wE3aHHBgkDIqwptdEsyrR2SV8.LNMSjpb_t2lZ3LxLsboGLj1ROvcX usSxUqrR1jNvNSVlkpLo_wsTs2ZIm119Ljc.3rQ-- Received: from [76.8.220.18] by web111404.mail.gq1.yahoo.com via HTTP; Thu, 08 Apr 2010 19:15:21 PDT X-Mailer: YahooMailClassic/10.0.8 YahooMailWebService/0.8.100.260964 X-Original-Date: Thu, 8 Apr 2010 19:15:21 -0700 (PDT) From: randy snarr Subject: Re: [LML] FW: [LML] gear retract problems X-Original-To: Lancair Mailing List In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-1643237629-1270779321=:87432" --0-1643237629-1270779321=:87432 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable FWIW, I just replaced the dump valve with a swageloc PN SS-42GXHF2 and ran a=A0ny= lon low pressure line back the the resevoit with the extra port. As Wolfgan= g stated there was some plumbing, but it was easy to lay in a single low pr= essure line and replace the valve. The whole thing took a Saturday and it was done... Randy Snarr N694RS --- On Thu, 4/8/10, Wolfgang wrote: From: Wolfgang Subject: [LML] FW: [LML] gear retract problems To: lml@lancaironline.net Date: Thursday, April 8, 2010, 7:13 PM Randy Snar in his just posted comments has hit the nail on the head. The sp= ool in the hydraulic pump does not always stay at the end point of it's tra= vel and when it doesn't, and since there is no accumulator in the system, t= he fluid volume is trapped and heat will cause thermal expansion opening th= e pressure switches. If you don't experience a large temperature rise and t= he spool in your pump stays where it's supposed to, you won't see the probl= em. So as Randy stated, if both switches trip, nothing works except opening= a fitting to relieve the pressure. Installing a "dump" valve that vents bo= th sides to the reservoir instead of the standard of just equalizing betwee= n both sides will fix the problem but still requires pilot=A0intervention a= fter the re-plumbing. But how many people are ready to re-plumb their hydra= ulics to implement that fix ? =A0 There is nothing in the pump except o-ring friction to keep the spool in it= 's needed end position. Vibration can move it trapping the fluid volumes. A= ctivating the pump will force the spool back into it's end position=A0relie= ving the offending pressure and all is well with the world. Problem is the = pressure switch is open preventing the pump from activating. Forcing the pu= mp to activate when both switches are open will do the trick. My=A0electric= module does exactly that . . . . automatically . . . . without pilot inter= vention. It connects to both pressure switches and forces the pump to activ= ate in the direction selected by the gear switch if both pressure switches = are open. =A0 Wolfgang =A0=0A=0A=0A --0-1643237629-1270779321=:87432 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
FWIW,
I just replaced the dump valve with a swageloc PN SS-42GXHF2 and ran a nylon low pressure line back the the resevoi= t with the extra port. As Wolfgang stated there was some plumbing, but it w= as easy to lay in a single low pressure line and replace the valve.<= /DIV>
The whole thing took a Saturday and it was done...
Randy Snar= r
N694RS

--- On Thu, 4/8/10, Wolfgang <Wolf= gang@MiCom.net> wrote:

From: Wolfgang <Wolfgang@MiCom.net>
Subj= ect: [LML] FW: [LML] gear retract problems
To: lml@lancaironline.net
= Date: Thursday, April 8, 2010, 7:13 PM

Randy Snar in his just posted comments has= hit the nail on the head. The spool in the hydraulic pump does not always = stay at the end point of it's travel and when it doesn't, and since there i= s no accumulator in the system, the fluid volume is trapped and heat will c= ause thermal expansion opening the pressure switches. If you don't experien= ce a large temperature rise and the spool in your pump stays where it's sup= posed to, you won't see the problem. So as Randy stated, if both switches t= rip, nothing works except opening a fitting to relieve the pressure. Instal= ling a "dump" valve that vents both sides to the reservoir instead of the s= tandard of just equalizing between both sides will fix the problem but stil= l requires pilot intervention after the re-plumbing. But how many people are ready to re-plumb their hydraulic= s to implement that fix ?
 
There is nothing in the pump except o-ring= friction to keep the spool in it's needed end position. Vibration can move= it trapping the fluid volumes. Activating the pump will force the spool ba= ck into it's end position relieving the offending pressure and all is = well with the world. Problem is the pressure switch is open preventing the = pump from activating. Forcing the pump to activate when both switches are o= pen will do the trick. My electric module does exactly that . . . . au= tomatically . . . . without pilot intervention. It connects to both pressur= e switches and forces the pump to activate in the direction selected by the= gear switch if both pressure switches are open.
 
Wolfgang
 

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