Just found this in my Sailtec documentation,
Pressure (PSI) Reading (#) Tension Cyl. Diameter Cyl. Bore -08 size matches .6:1.00 psi 1.50" 1.002 -10 size matches 1:1.00 psi 1.75" 1.250 -12 size matches 1:1.30 psi 2.00" 1.500 -17 size matches 1:1.76 psi 2.25" 1.750 -22 size matches 1:2.20 psi 2.75" 2.000 So it does look like the -10 is Hydraulic pressure = Tensile # I learn something every day. I have two -10 cylinders on a split backstay, so I guess 1,000# pressure = 2,000 tensile#. They don't make it easy to find all this stuff. Bill Coleman Entrada, Erie, PA From: Jeffrey A. Laman via CnC-List [mailto:cnc-list@cnc-list.com] Sent: Monday, April 19, 2021 11:07 AM To: Stus-List Cc: Jeffrey A. Laman Subject: Stus-List Re: Hydraulic backstay adjuster pressure? Hi All. Also wanted to comment on the pressure question. As I noted in my post about the NavTec - 10 failure, I have been examining all the issues that I more or less ignored or was happily ignorant of till now. One item was to determine the yield and breaking load on my backstay and correlating backstay shortening to load. If you do a little geometry and have knowledge of stress/force/strain/elongation, it is a fairly simple determination (I am a structural engineer). Others have provided photos of simple shortening measure devices, which I now intend to make and install. If others have photos, please share! But, one comment on pressure and force -- the pressure on the hydraulic backstay is directly related to force. So, if I trouble myself to read it, I will pay much more attention to the pressure on the gauge right in front of my face. At the moment, I don't recall what I read -- either NavTec or SailTec, or maybe both, 1000 psi = 1000 lbs force. The NavTec - 10 has a relief valve set to 4000 lbs. SailTec - 10 is 4750 lbs. Others with more knowledge may have more definitive information. Long story but I received the wrong SailTec - 10 the first time -- a custom unit for J105s that has a pressure relief at 3000 lbs. Excellent discussion, btw everybody! Jeff L.
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