Railway Preservation News

Cylinder Cocks
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Author:  Hume Kading [ Mon Sep 21, 1998 4:18 am ]
Post subject:  Cylinder Cocks

In my quest to learn more about steam locomotives my question for the month is about cylinder drain cocks. I know they allow (conedensed?) accumulated water to be removed from the cylinders rather than popping off a cylinder head. How could so much water accumulate in a cylinder? I have seen pictures of engines running with the cocks open, and blowing steam out the bottom. Is this just for show (like black smoke)? And finally, how does the engineer control the opening and closing of the cocks from the cab? Steam, pneumatic, hydraulic?<p>Thanks.

Railway Preservation News

Author:  Dave [ Mon Sep 21, 1998 8:16 pm ]
Post subject:  Re: Cylinder Cocks

Sometimes it is for show. You often see EUREKA running with cocks open because Dan likes the look of the steam blowing off. <p>Throttles all leak to some extent, and hydrostatic lubricators deliver oil in a jet of steam. When the locomotive isn't running it condenses on the cooling cylinder surfaces. <p>Water isn't compressible (which makes hydrostatic testing safe) and must be removed or there is a danger of blowing off a cylinder head with trapped water so we have cylinder cocks to do the job. <p>Some are manually operated with a seried of rods and levers, and some are operated with steam or air. Some will open automatically at set pressures to relieve any condensation which develops even if the engineer forgets to open them. Several designs were described in the old Cyclopedias of the '20s and '30s.<p>New copies of manual Baldwin cocks are available from Backshop - Lou Dahm had to make some for Colo Rr Museum some time back and Bernie has the patterns. <p>Dave<br>


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