# MU question, different locomotives speed limits



## MattW (Oct 31, 2010)

Let's say an MP15 can haul itself at a maximum of 50mph (but allowed to be pulled at track speed) while a P42 can haul itself at 110mph. If the "train" is being controlled from the MP15 and the appropriate MU cable is hooked up, would the train be capable of the P42's maximum speed, or would it be stuck doing the MP15's maximum speed. What about when driving from the P42?


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## AlanB (Oct 31, 2010)

Unless the MP15 doesn't have PTC I would imagine that the P42 would then be able to push the train at 110MPH.


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## jis (Nov 1, 2010)

AlanB said:


> Unless the MP15 doesn't have PTC I would imagine that the P42 would then be able to push the train at 110MPH.


But this would be legal only if the MP15's running gear is certified to operate at 110mph while being pushed.


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## AlanB (Nov 1, 2010)

jis said:


> AlanB said:
> 
> 
> > Unless the MP15 doesn't have PTC I would imagine that the P42 would then be able to push the train at 110MPH.
> ...


Agreed, which I believed that the OP had covered with:



MattW said:


> (but allowed to be pulled at track speed)


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## George Harris (Nov 2, 2010)

Generally, in railroad rule books the speed limit for an engine consist is limited to the maximum allowed for the slowest unit.


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## battalion51 (Nov 19, 2010)

On Amtrak property most units have a Maximum Speed permitted of 65 MPH or more. There are a few SW/Slug units that are lower, but beyond that they're all good for 65 MPH. So if there were a need to move the units between yards, you can put it on a manifest train (which will be restricted to 60 MPH anyway) and then still be able to move at track speed.


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