Reply to "METRA to Purchase SD70MACs for commuter service."

Krieglok posted:
Hot Water posted:
Dominic Mazoch posted:

And how fast will these locomotives have to go in commuter service?  My guess is they will need to go much faster than passenger trains on the Alaska.

I would think that they should be capable of at least 75 MPH.

They will likely be geared for passenger service rather than freight, giving them a higher top speed. The gearing for passenger locomotives reduces the overall tractive effort for heavy loads but increases the acceleration rate from a standstill as well as giving the higher top speed...

I wish NJT would consider these engines in the future!

Tom

For what it's worth, the BN/BNSF SD70MAC units were already "geared" for 70MPH with the overspeed set for about 72 in the speed-control system. Unlike a DC traction motor, with its copper commutator bars that are subject to damage from high centrifugal forces, the AC three phase induction tractor motor rotor is not seriously affected by centrifugal forces.

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