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Milwaukee Road History: The Milwaukee Electrification, page 10


Regenerative braking, little understood in 1915 except by electrical engineers, is a technique which simplified and increased the safety of mountain operation, reduced wear on brake shoes and actually recovered electrical power and returned it to the overhead system for use by other trains.

The Milwaukee has long been proud of this feature. The Milwaukee Road Magazine in 1916 described regenerative braking as

“a process of producing electrical current within the motors of the locomotive by converting the motors into generators, and the current thus produced being returned to the trolley; and the force of gravity which tends to make the train run away down grade is the power that drives the generators, and the work thus performed operates to hold the train back.”

Once on a down grade, the engineer throws a switch in the cab and regeneration takes over. The desired speed is maintained by use of the line current control. The trains are equipped with air brakes, but air is used only while switching into regenerative braking and as a back-up system in case of emergency.

Returning current to the line has proved an economic boon, since 40 to 60 per cent of the power used ascending a grade can be returned while de­scending. With the numerous grades in the Milwau­kee’s mountain electrification, the railroad recovers about 12 per cent of the total energy used by its electric locomotives and returns it to the system, powering other locomotives or receiving credit from the power suppliers.

Regenerative braking is now widely used throughout the world and has been a feature of all other types of Milwaukee Road electric locomotives.



Benefits of regenerative



-Simplified, safer mountain operation


-Reduced wear on brake shoes


-Recovered electrical power














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Last Updated: October 07, 2007