X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sat, 17 May 2014 11:40:48 -0400 Message-ID: X-Original-Return-Path: Received: from [107.14.166.232] (HELO cdptpa-oedge-vip.email.rr.com) by logan.com (CommuniGate Pro SMTP 6.0.9e) with ESMTP id 6876155 for lml@lancaironline.net; Fri, 16 May 2014 10:42:49 -0400 Received-SPF: none receiver=logan.com; client-ip=107.14.166.232; envelope-from=Wolfgang@MiCom.net X-Original-Return-Path: Received: from [74.218.201.50] ([74.218.201.50:1534] helo=lobo) by cdptpa-oedge03 (envelope-from ) (ecelerity 3.5.0.35861 r(Momo-dev:tip)) with ESMTP id E7/4B-14070-5C326735; Fri, 16 May 2014 14:42:13 +0000 X-Original-Message-ID: From: "Wolfgang" X-Original-To: "Chris Zavatson" , References: Subject: Re: Hydraulic Pressure Spike Video X-Original-Date: Fri, 16 May 2014 10:42:08 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0050_01CF70F3.7C5039B0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5512 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.5512 X-RR-Connecting-IP: 107.14.168.142:25 X-Cloudmark-Score: 0 This is a multi-part message in MIME format. ------=_NextPart_000_0050_01CF70F3.7C5039B0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Of course there's a pressure spike. Standard in all hydraulic systems.=20 That's what happens when you start pumping fluid faster than the inertia = of the gear can follow. Think about it=20 . . . when you start to push your car you have to apply a lot of = pressure=20 . . . but less pressure to keep it rolling. So the pressure spike can open up the switch=20 . . . fine=20 . . . then the pressure gets relieved as the gear starts to move=20 . . . and the switch closes again=20 . . . and the motor runs again=20 . . . until the real end of stroke makes the pressure go high and stay = hi holding the pressure switch open. This is a non-problem. . . . let it go already. Wolfgang ----- Original Message -----=20 From: Chris Zavatson=20 Sent: Thursday, May 15, 2014 7:33 AM Subject: Hydraulic Pressure Spike Video Using my iPhone I took a video of my pressure gauges while extending = my gear on a flight today. It is starting to warm up out here. We're = not cooking yet, but it is enough to start observing the hydraulic = pressure spike which was the subject of a previous LML thread. It was a bit bumpy on downwind, but the gauges are still clearly = visible in the video. The high pressure circuit was just a hair under 1,500 psi when = gear-down was selected. One can hear the pump fire up and release the = gear, The high side pressure begins to drop and then the spike = immediately hits the low side. It reached 450 psi in this clip. If the = spike reaches the low side pressure switch setting, the pump solenoid = will open and the pump will shut down. I have my low side pressure = switch set to 800 psi which has proven to be high enough to avoid any = gear hesitations and/or extension failures. http://n91cz.com/Hydraulics/GearExtensionPressureSpike.mp4 (hi res = 16Mb) http://n91cz.com/Hydraulics/GearExtensionPressureSpike-lores.mp4 (lo = res 3Mb) Chris Zavatson N91CZ 360std www.N91CZ.net ------=_NextPart_000_0050_01CF70F3.7C5039B0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Of course there's a pressure spike. = Standard in all=20 hydraulic systems.
That's what happens when you start = pumping fluid=20 faster than the inertia of the gear can follow.
 
Think about it
. . . when you start to push your car = you have to=20 apply a lot of pressure
. . . but less pressure to keep it=20 rolling.
 
So the pressure spike can open up the = switch=20
. . . fine
. . . then the pressure gets relieved = as the gear=20 starts to move
. . . and the switch closes again =
. . . and the motor runs again =
. . . until the real end of stroke = makes the=20 pressure go high and stay hi holding the pressure switch = open.
 
This is a non-problem. . . . let it go=20 already.
 
Wolfgang
 
----- Original Message -----
From:=20 Chris=20 Zavatson
Sent: Thursday, May 15, 2014 = 7:33=20 AM
Subject: Hydraulic Pressure = Spike=20 Video

Using my iPhone I took a video of my pressure gauges while = extending my=20 gear on a flight today.  It is starting to warm up out=20 here.  We're not cooking yet, but it is enough to start = observing=20 the hydraulic pressure spike which was the subject of a previous LML=20 thread.
It was a bit bumpy on downwind, but the gauges are still clearly = visible=20 in the video.
The high pressure circuit was just a hair under 1,500 psi when = gear-down=20 was selected.  One can hear the pump fire up and release the = gear, =20 The high side pressure begins to drop and then the spike immediately = hits the=20 low side. It reached 450 psi in this clip.  If the spike reaches = the low=20 side pressure switch setting, the pump solenoid will open and the pump = will=20 shut down.  I have my low side pressure switch set to 800 psi = which has=20 proven to be high enough to avoid any gear hesitations and/or = extension=20 failures.

http:= //n91cz.com/Hydraulics/GearExtensionPressureSpike.mp4    = (hi res=20 16Mb)
http://n91cz.com/Hydraulics/GearExtensionPressureSpike-lores.mp4&nbs= p; =20 (lo res 3Mb)

Chris Zavatson
N91CZ
360std
www.N91CZ.net

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