November 06, 2004 02:51PM
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Mike, I think I have read this description in one of the Kirkman "Science of Railways" books. Someone correct me if I have this goofed up or have omitted details. When drifting down hill with a light engine, there are two ways to control the speed. One is obviously with the air brake, but this has the problem of heating and loosening tires if brakes are applied too long. The other way is to drift with the Johnson bar slightly towards reverse. This casues compression at the end of the piston strokes to retard forward movement kind of like a Jake brake on a truck. The downside of this is that compression causes heat and unless a small amount of steam is allowed to flow to the cylinders, lubrication becomes a problem. In either case, the temperatures in the cylinders can become very high due to compression (like occurs in a diesel engine) which reduces the effectivness of lubrication. The water brake allows the engineer to pass a small amount of water from the boiler to the cylinders. This water which will be at the same or near the temp of steam in the boiler will flash to steam because of the lower pressure in the valve chest and cylinders and will act to cool the cylinders relativly speaking and the expansive force of this low pressure steam will help to retard the movmement of the engine. The downside of the water brake is that if the engineer were to introduce too much water flashing to wet steam to the cylinders, the expansive force of this steam plus compression could result in pressures beyond the structual limits of the cylinders heads, crossheads or other moving parts resulting in catastrophic failure of some part.
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Author |
Posted |
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Andy Roth |
November 03, 2004 08:51AM |
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WilliamDiehl |
November 03, 2004 09:59AM |
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Paul Gibbs |
November 03, 2004 12:38PM |
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Fritz Klinke |
November 03, 2004 04:01PM |
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Paul Hagglund |
November 03, 2004 04:22PM |
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Mike Trent |
November 03, 2004 04:44PM |
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Mike Trent |
November 03, 2004 04:31PM |
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Fritz Klinke |
November 03, 2004 07:00PM |
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Crayuft |
November 04, 2004 04:52AM |
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Mike Trent |
November 04, 2004 05:23AM |
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Ryan Scott |
November 03, 2004 08:27PM |
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J. Johnson |
November 04, 2004 04:50AM |
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Greg scholl |
November 04, 2004 07:28AM |
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Crayuft |
November 04, 2004 08:04AM |
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John Hillier |
November 04, 2004 09:18AM |
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Greg scholl |
November 04, 2004 09:26AM |
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John Hillier |
November 04, 2004 10:04AM |
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Greg scholl |
November 04, 2004 12:02PM |
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Kevin Cook |
November 04, 2004 01:07PM |
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Greg scholl |
November 04, 2004 01:15PM |
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Greg scholl |
November 04, 2004 01:16PM |
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John Craft |
November 04, 2004 02:38PM |
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Ben Quirk |
November 04, 2004 02:59PM |
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Paul Hagglund |
November 04, 2004 03:30PM |
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J.B.Bane |
November 04, 2004 07:30PM |
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John Hillier |
November 04, 2004 08:58PM |
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J. Johnson |
November 04, 2004 11:46PM |
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Jerry Day |
November 05, 2004 08:04AM |
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Tom Farmer |
November 05, 2004 02:22PM |
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Jerry Day |
November 05, 2004 02:35PM |
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Josh McNeal |
November 06, 2004 10:17AM |
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J. Johnson |
November 06, 2004 11:41AM |
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Earl |
November 07, 2004 02:22PM |
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J. Johnson |
November 07, 2004 04:49PM |
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Paul Hagglund |
November 08, 2004 04:26PM |
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Eric Dowty |
November 08, 2004 09:34PM |
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The Josh |
November 06, 2004 12:37AM |
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Dan Robirds |
November 06, 2004 10:21AM |
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WP&Ymike |
November 06, 2004 11:35AM |
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J.B.Bane |
November 06, 2004 02:51PM |
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Wooly |
November 06, 2004 06:08PM |
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Dan Robirds |
November 06, 2004 06:08PM |
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Paul Gibbs |
November 06, 2004 07:55PM |
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Ed Stabler |
November 06, 2004 08:17PM |
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Hollywood |
November 05, 2004 08:46AM |
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Hollywood |
November 05, 2004 08:49AM |
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Hollywood |
November 05, 2004 08:52AM |
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Greg scholl |
November 05, 2004 11:33AM |
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Crayuft |
November 05, 2004 04:33PM |
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J. Johnson |
November 05, 2004 06:52PM |
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Greg scholl |
November 05, 2004 09:03PM |
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