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  • Effects of MUing different types of EMUs?

  • General discussion of passenger rail systems not otherwise covered in the specific forums in this category, including high speed rail.
General discussion of passenger rail systems not otherwise covered in the specific forums in this category, including high speed rail.

Moderators: mtuandrew, gprimr1

 #1301882  by MattW
 
I think I had read sporadically on here problems with "mismatched" EMUs. For instance maybe a Silver Liner IV with a III in the consist. Generally speaking, what sort of problems can typically result from running different models/classes of EMUs together? Flat Spots?
 #1342168  by Gerry6309
 
MattW wrote:I think I had read sporadically on here problems with "mismatched" EMUs. For instance maybe a Silver Liner IV with a III in the consist. Generally speaking, what sort of problems can typically result from running different models/classes of EMUs together? Flat Spots?
Two question have to be answered:

1) Were the cars designed to operate in the same train?

If the answer is "No", the results of attempted operation may be blown fuses, circuit cards and other components. The offending equipment and anything coupled behind it will not operate. Cars ahead of the offending equipment may not operate properly either. The reason will be that the MU cables between the cars do not connect the same circuits, or may not even match.

If the answer is "Yes", we proceed to question 2

2) Are the operating characteristics of the cars compatible?

If the answer is "Yes" there should be no problems other than those encountered in normal operation of like cars.

If the answer is "No" then there will be problems at the couplers due to the differences in performance, but flat spots are unlikely unless the standard braking systems are not used.
 #1342183  by R36 Combine Coach
 
When running mixed equipment, the side effects are often rough braking, "bucking" and riding if all cars are electrically or mechanically compatible. Examples including NYCT (all postwar SMEE passenger equipment from R10 to R42) and LIRR (passenger equipment 1908/1910 (MP54) to 1963 (MP75). On NJT, even mixed single level sets can be quite rough with Comet II-V in one train.
 #1342335  by Gerry6309
 
DutchRailnut wrote:you lost me on NJT when did Comets become EMU's ?
They didn't, but the braling effort and control is different, hence a certain reduction may have a different effect on different cars. Therefore you get the same effects at the couplers as cars brake at different rates.