LP valve balance pistons

[Sec']

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???

 

[Bob Read]

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']

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

 

[Bob Read]

Oh, ok. Aren’t those the actual valves of the valve chest?

 

[Sec']

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...

 

[Bob Read]

Maybe this will help: Titanic’s Propulsion Plant

 

[Sec']

Cheers for the link, that's a great read. Sadly doesn't mention these though

 

[Tim Aldrich]

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.

 

[Sec']

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)

 

[Tim Aldrich]

Glad you found an answer to your questions. It's a good book isn't it?

 

[Sec']

Glad you found an answer to your questions. It's a good book isn't it?

Yes thanks it's full of great detail. An engine Bible of the day. Interesting stuff