02-03-2018, 03:31 PM
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#13
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Guru
City: East Coast, Australia
Join Date: Jun 2012
Posts: 935
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From post #6 in a thread by obthmas started 07-01-2014 by rduval: TheUniflow valve is a set of shuttle valves so the cylinder has a return path to the helms whether going to port or to starboard. The helms do not have checkvalves as the uniflow eliminates the need.
And from obthomas post #13 in that same thread: the purpose of the univalve isto eliminate check valves at the helms.
obthmas also posted a number of very useful Capilano documents in that thread, which explain exactly how the Uniflow valve is to be installed and how it can be used to simply & easily bleed the system. The key point I think is that theCapilano/Teleflex 250V-based systems are not true 3-line, but 2-line systems; the 3rd line from the Univalve is not pressurized for steering, but 'just' provides a return pathway back to the helm pumps. These systems were regarded as best-in-class in their day and were installed in many commercial vessels doing hard service.
There is also the mysterious, recurring reference to a Vetus solution: I think most of these are in fact quoting the one 2006 online source (details below),which says:
"What to do if your Univalve fails? I have found a company by the name of Vetus Den Ouden, Inc which is a Netherlands company. They have US distribution from Maryland, see www.vetus.com.
This company sells their own pumps cylinders etc primarily in the European market. Their pumps are sold with a built in return valve or without. For the "non-return" pumps, they route expelled steering slave cylinder fluid through a "non-return" valve block (same idea as the Uvalve). This valve
is available as part number K30/140 for $US260. The drawback is that the entire Vetus line of steering components is plumbed in metric fittings. With a little creativity, this speed bump can be circumvented. You could save your old sytle Capilano pump which use the 3 line system. Vetus [also] offers another valve which will serve as a Non-return block. This one also has a by-pass valve built into it which will allow for system bleeding and in the event you need to put a tiller onto your rudder in an emergency steering situation. This non-return/bypass valve is over $600,..."
[source: http://lists.trawlering.com/pipermai...l/103867.html]
I think it would be worth following up this Vetus reference, which isvery specific. And if not Vetus, another generic bypass-valve solution. I suspect Ski (Eric's)post could have the answer. While Teleflex & Seastar don't provide direct replacements, it doesn't seem like what the U-50 is doing is unique in the hydraulics world. SeaStar & others have a commercial interest in 'upgrading' customers to the newer...but not necessarilybetter....1250 (and equivalent) helm pumps. At around $1,000+ for each pump before the skilled labour involved in removing not just the 250V pumps but univalve and 3rd line (yes, it could be just capped off), those with 2+ helms who think they need to go this route might want to evaluate jumping even further along the technology chain to even newer solutions from other vendors
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