Return-Path: Sender: (Marvin Kaye) To: lml Date: Sun, 27 Oct 2002 18:31:48 -0500 Message-ID: X-Original-Return-Path: Received: from pop3.olsusa.com ([209.26.218.2] verified) by logan.com (CommuniGate Pro SMTP 4.0) with ESMTP id 1846207 for lml@lancaironline.net; Sun, 27 Oct 2002 17:01:11 -0500 Received: from tomts10-srv.bellnexxia.net ([209.226.175.54]) by pop3.olsusa.com (Post.Office MTA v3.5.3 release 223 ID# 0-71866U8000L800S0V35) with ESMTP id com for ; Sun, 27 Oct 2002 16:51:24 -0500 Received: from a ([65.93.231.227]) by tomts10-srv.bellnexxia.net (InterMail vM.5.01.04.19 201-253-122-122-119-20020516) with SMTP id <20021027220042.FOGP3451.tomts10-srv.bellnexxia.net@a>; Sun, 27 Oct 2002 17:00:42 -0500 X-Original-Message-ID: <000701c27e04$cd64cee0$e3e75d41@a> From: "Ian B. Crowe" X-Original-To: "Marvin Kaye" X-Original-Cc: Subject: LNC 2 hydraulics X-Original-Date: Sun, 27 Oct 2002 17:04:20 -0500 Organization: Corvi Trade Consultants Inc MIME-Version: 1.0 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 I have recently tested my hydraulic system for the gear. I have installed two pressure guages on the high and low pressure circuits.I have the new emergency extension cock, there are no visible external leaks and the problem is very intermittent. The gear extends and retracts in 8 to 10 seconds. On retraction the mains lead the nose to the extent that the mains are in the well before the nose starts to retract. The pressure gauges show only a small increase in pressure on retraction until the gear is fully up when the pressure rises and the pump shuts down. The same applies on the extension cycle when the gear is fully down and locked the low pressure rises to 700 psi and the pump shuts down. In other words the system takes very little force to operate until the cylinders reach their stops. It is on the extension cycle that a very intermittent problem has surfaced. The gear goes down and locks. The pressure builds up to 700 psig and the pump shuts down. The low pressure starts to bleed off and it is possible to see the high pressure gauge move off its zero position as the low pressure drops.. The pump cuts in restores the pressure, shuts off and the cycle begins again. If the gear is retracted and again extended the problem disappears. It appears as if the low pressure is leaking across to the high pressure side but not every time. If you leave the system off overnight in the morning there will often be 400 to 500psig left in the circuit. So what is happening? The gauges suggest that the low pressure is migrating to the high pressure side either across the emergency extension cock or across the piston of one or more of the double acting cylinders. But why not all the time? Could it be air in the system? How do you trouble shoot an intermittent fault ? In theory I should be able to blank off the LP pressure to the cylinders until the fault disappears but I may not get the fault to reappear on command! Perhaps I should start with the cock. Another probability is that I have a bubble of air somewhere. Any ideas anyone? Ian Crowe