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B unit maximum
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[quote]QUOTE: <i>Originally posted by Mark_W._Hemphill</i> <br /><br />[quote]QUOTE: <i>Originally posted by teamdon</i> <br /> Drawbar tonnage ring a bell ????...It's really very simple if you cut through the ?&*#...... <br />[/quote] <br />Did you miss the original question? It asked the maximum number of B units a railroad could M.U. When F-units were running, there were <b>three </b>things that determined that maximum number, not just drawbar limits: <br /> <br />1. Drawbar limits and buff forces (determined by the physical plant) <br />2. M.U. signal competence (usually limited the consist to 8 units) <br />3. Type of dynamic braking on railroads so equipped. <br /> <br />Let me try again. A railroad prior to 1953 using EMD units could *always* m.u. more than four units up to the limits of the physical plant and the trailing tonnage *unless* it wanted to use dynamic brakes, where there was an absolute limit of four units *regardless of drawbar limits* set by the electrical system of the dynamic brakes. For example, Rio Grande typically set F-unit freight consists at four units up through model F7, because that is the total number of units the dynamic brakes would support. This has absolutely nothing to do with drawbar limits, which is a separate matter. After EMD developed point-potential brakes, Rio Grande upgraded its F7s (but not the FTs) so it could start building five-unit and six-unit sets of F-units AND have dynamic braking on all units. <br /> <br />I used to assign the power to 20-40 trains a night, and choose the points where the manned helpers and distributed power were cut in and cut out over a two-crew mountain district with five helper grades and some very difficult buff force problems. It wasn't much fun, because there was never enough power to satisfy the operating plan, and never enough rested crews or good power. <br /> <br />Come on over here to Iraq -- the U.S. Government can use people like you that have lots of ambition and pride. <br />[/quote]
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