On Tue, May 26, 2009 at 8:03 PM, Joseph McAllister <[email protected]> wrote: > On May 26, 2009, at 07:18 , Graydon wrote: > >> The fundamental limits on train size are engine traction and drawbar >> strength. >> >> Remember that when starting the train, at some point the engine to first >> car drawbar has the entire mass of the train on it; this turns out to be >> more of an issue than engine traction. Past a certain size, you get an >> awful ping noise as a drawbar breaks, and then you have *two* trains. > > Isn't the drawbar heavily spring loaded, so as to allow the engine to at > least get it's wheels turning a tiny bit before the weight of the train is > slowly, but quickly, pressed upon it? I'm talking only a few inches of > spring compression with a heavy load, but it does change the math a bit. > > Am unable to find any drawings or descriptions in cursory search, so I may > be mistaken, confusing model railroad engines to line engines. Anyone know > fer certain? > > > Joseph McAllister
Yes, and before starting a large train they push it together to take up the slack, which allows the train to get teh front cars moving before the rear cars, reducing the total force required as you only have to overcome one cars coefficient of static friction at a time. -- M. Adam Maas http://www.mawz.ca Explorations of the City Around Us. -- 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.
