LP valve balance pistons


Sec'

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Aug 22, 2018
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I've seen pistons fitted on top of the valves on the LP cylinders. They're on the Brittanic's piston valves, but also shown on a photo of Titanic's slide valves. I guess they're for balancing but can't see why, especially for slide valves. Anyone have any ideas???
 

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Bob_Read

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If I am mistaken, somebody can correct me but I believe that at the top of each cylinder is a pressure relief safety valve.
 

Sec'

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Aug 22, 2018
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Yes there were relief valves on the top of the cylinders and valve chest. But these pistons are separate
 

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Sec'

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Aug 22, 2018
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No, sorry that last diagram doesn't show the pistons I'm asking about, just the relief valves you mentioned. Hope this diagram makes it clearer...
 

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Tim Aldrich

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Jan 26, 2018
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Get on Google Books and look up Richard Sennet's "The Marine Steam Engine". I seem to recall something about balance valves in that book.
 
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Sec'

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Aug 22, 2018
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Sorry for the delay but THANK you Tim!
I found a free copy of the book online and finally got to page 213 where there they were!
Yes, balance valves are what they are, balancing for the weight of valve and rod.
To summarise: the bottom of this small piston is open to the high pressure steam side of the valve chest, the top of the balance piston is piped into the exhaust steam pipe.
I'll post a link to this free book (and many more copyright expired books in a new thread)