Joseph McAllister wrote: >On May 26, 2009, at 20:29 , Bob Sullivan wrote: > >> There can be 6 inches of slack per car in a train. This can help you >> start a train rolling as you stretch out the accordion one car at a >> time. Remember the locomotives only weigh so much and the coefficient >> of friction of steel wheels on steel rail is only .03 or so (even if >> you're sanding the rail). Getting going can be tough. And being in >> the 100th car back can give you a bad case of whiplash as the momentum >> of 99 cars moving at 1/2 mile per hour accelerate you to 1/2 mile per >> hour instantly! >> But the slack can also play havoc with the train over the road. >> Imagine a slight grade, followed by a dip, followed by another grade >> and a 100 car train of loaded coal hoppers. The engines strain to >> take you over the first grade and you stretch out all the slack on the >> way up. But on the way down, you compress the slack out of the train >> and then play 'crack the whip' on the way up, pulling the slack back >> out. If you're lucky, you don't break a coupler and make 2 train >> segments. >> Regards, Bob S. > >Probably does not happen much anymore without a defect or a rapidly >arising situation, given that the modern engines are controlled >digitally, and that control is, among other things, modified by the >digital strain gauges that are located throughout the construct.
Oh bloody hell... *trains* have gone digital now? Is nothing sacred? -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
