Talk:Hammer blow

Trains: in UK / Locomotives Mid‑importance

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DYK	May 27, 2008

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Piston thrust[edit]

I have removed the uncited hammer blow reference to piston thrust for a couple of reasons. HB is explicitly defined in terms of what causes it and how it is calculated in a range of books from textbooks on machine dynamics to books written first hand by locomotive designers. Piston thrust is not a contributor. Con rod angularity causes varying rail loads and should be explained, I think, rather than just calling the piston thrust HB. It could still appear in this article under a heading , say "other causes of variable wheel-rail loading", which would also be the place for something on P1/P2 forces.

I have also removed the uncited reference to crocodile electrics as I cannot find anything to support it. I have found just the opposite in Haut's "Pictorial history of electric locomotives"... for drives through gear wheels, jack shafts and connecting and driving rods it was possible to balance all moving masses completely. Likewise for diesels.. no reciprocating masses to be balanced with overbalance in the wheels, so no HB.Pieter1963 (talk) 22:06, 26 August 2014 (UTC)[reply]

Inside Cylinders and Hammer Blow[edit]

> The usage of inside cylinders (which was rare in the USA) results in a more stable locomotive and thus reduced hammer blow. This seems very dubious to me - or at least half the story. Inside cylinders don't of themselves reduce hammer blow. What the author may mean is that with inside cylinders the out of balance longitudinal forces are acting over a much narrower lever (piston centres under 3 ft apart instead of over 5) so that although fore and aft out of balance forces are effectively the same, the induced lateral rocking (swaying couple is the technical term used I believe) is much less. This *may* mean that the amount of reciprocating balance could be reduced. This paper seems relevant to the topic, but I haven't sufficiently digested the technical detail. Perhaps another writer would like to. http://5at.co.uk/uploads/Articles%20and%20papers/The%20Balancing%20of%20the%20BR%20Class%209%202.PDF 212.159.44.170 (talk) 19:57, 11 September 2015 (UTC)[reply]