Question for MNCR engineers

I've never been on a train that changes voltage like the NH line does when it changes from AC catenary to DC third rail. Is there a noticeable change in the train handling behavior (IE acceleration) at the time the train changes voltage?

Im not an engineer, but the MC is in coast when going through changeover, so it's not like you feel a sudden jolt. Acceleration is better in AC mode though.

RearOfSignal wrote:Im not an engineer, but the MC is in coast when going through changeover, so it's not like you feel a sudden jolt. Acceleration is better in AC mode though.

You may not be an engineer, but your answer is accurate. Acceleration is much better in AC mode.

This condition did not only apply to current equipment on Metro-North but was also true with the 4400 class MU's, the old Green Muts and all classes of electric locomotives which were capable of both AC and DC operation. I can remember the Jets (370 class motors) which would just about make 60 MPH on the Central but once the pan went up at Mount Vernon we could go like the wind. On both the jets and the old Green Muts the controller was used in a different manner on DC as compared to AC. On the Jets there were only two running notches 19 and 31 while on AC the running notches were 19, 23, 27, 31 and 35. On the old Green Muts the controller was somewhat like a K-6 or K-35 trolley car controller only with a deadman handle included. On AC points 3, 5 and 7 were running points while on DC points 7 and 12 (full series and full parallel) were running points. The old Green Muts would really move out on AC but were somewhat sluggish on DC. The 4400's were not bad on DC but the problem here was that many of them had a shoe missing on each side and thus we lost third rail contact often.
Noel Weaver

M2's, M4's and M6's run better in AC than DC due to how their wired. In AC all traction motors are in parallel, therefore if one or more of the 4 traction motors is not working, the rest can still operate. However, in DC the motors are in series, so if one or more motors is not working, all 4 motors will be off line. This is done due to the high amperage in DC mode. The four motors all comsume the same amount of amps. So to prevent the other motors from overloading, they are disconnected.