Return-Path: Sender: "Marvin Kaye" To: lml@lancaironline.net Date: Thu, 13 Jan 2005 20:56:24 -0500 Message-ID: X-Original-Return-Path: Received: from mail.lancair-kits.com ([66.117.81.2] verified) by logan.com (CommuniGate Pro SMTP 4.2.8) with ESMTP id 606639 for lml@lancaironline.net; Thu, 13 Jan 2005 20:42:36 -0500 Received-SPF: none receiver=logan.com; client-ip=66.117.81.2; envelope-from=Rossc@lancair-kits.com Received: from LAI_DOM-MTA by mail.lancair-kits.com with Novell_GroupWise; Thu, 13 Jan 2005 17:42:07 -0800 X-Original-Message-Id: X-Mailer: Novell GroupWise Internet Agent 6.0.1 X-Original-Date: Thu, 13 Jan 2005 17:41:36 -0800 From: "Ross Connell" X-Original-To: X-Original-Cc: "Ben Phillips" , "Tim Ong" Subject: Over center link torsion (rat trap) springs 235/320/360 Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="=_92B2397F.2647282F" This is a MIME message. If you are reading this text, you may want to consider changing to a mail reader or gateway that understands how to properly handle MIME multipart messages. --=_92B2397F.2647282F Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit After reading the LML comments, and talking to Jim Rogers yesterday, this is what I remember about these torsion springs. The design was not for appearance purposes, but to produce a system to replace the tension springs which are folded and crushed in the retracted position. The first torsion springs were wound into to a coil to small so that when loaded they gripped the over-center link boss on the gear leg bending the spring. Next, the wire material would loose tension and on some the tang that connected to the gear leg would break off. The current spring is 3.5 coils of .135" 17-7SS, with a relaxed coil ID of .935". Looking back through the manuals and Supplement we showed a WS-6 washer on each side of the HF6 over-center link bearing in the old manuals, and a AN970-6 washer on the aft side of the bearing with a WS-6 forward, in newer manuals and the Supplement, either arrangement is ok if there is sufficient clearance. A WS-6 is nothing special, just a washer with a little larger OD than a AN960 and smaller than a AN970. One of the problems involved the length of the gear leg boss. Some of the older gear had bosses were shorter than .610" in those cases a washer aft of the bearing might bind the spring, if that is the case don't use a washer, let the bearing retain the spring. However you do it, make sure the spring is free to bend in the coils, without binding, and it will apply about 19 lbs to the link when pre-loaded 90 to 95 degrees. Finally the spring can't force the gear down, fortunately, gravity is pretty reliable, but, once down, the spring will hold the link in the over-center position. This is probably more than any one wanted to know about these springs, but since it was March 1995 when we first worked with a spring manufacturer, it's surprising to see this much interest 10 years later. Ross Connell --=_92B2397F.2647282F Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Content-Description: HTML
After reading the LML comments, and  talking to Jim Rogers yesterday, this is what I remember about these  torsion springs.
The design was not for appearance purposes, but to produce a system to replace  the tension springs which are folded and crushed in the retracted position.
The first torsion springs were wound into to a coil to small so that when loaded they gripped the over-center link boss on the gear leg bending the spring.
Next, the wire material would loose tension and on some the tang that connected to the gear leg would break off.
The current spring  is 3.5 coils of .135"  17-7SS, with a relaxed coil ID of .935".
Looking back through the manuals and Supplement  we showed a WS-6 washer on each side of the HF6 over-center link  bearing in the old manuals,  and a  AN970-6 washer on the aft side of the bearing with a WS-6 forward, in newer manuals and the Supplement,  either arrangement is ok if there is sufficient clearance. A WS-6 is nothing special, just a washer with a little larger OD  than a AN960 and smaller than  a AN970.
One of the problems involved the length of the gear leg boss. Some of the older gear had bosses were shorter than .610" in those cases a washer aft of the bearing might bind the spring, if that is the case don't use a washer, let the bearing retain the spring.
However you do it, make sure the spring is free to bend in the coils, without binding, and it will apply about 19 lbs to the link when pre-loaded 90 to 95 degrees.
Finally the spring can't force the gear down, fortunately, gravity is pretty reliable, but, once down, the spring will hold the link in the over-center position.
This is probably more than any one wanted to know about these springs, but since it was March 1995 when we first worked with a spring manufacturer,  it's surprising to see this much interest 10 years later.
Ross Connell
       
 
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