Union Pacific Railroad and ZTR Control Systems (“ZTR”), a green technology company and leader in locomotive control systems, today announced a partnership to build hybrid-electric locomotives.

The locomotives, which will run as “Mother-Slug” units, work much like today’s plug-in hybrid car, capable of operating in multiple modes including single engine, battery-assisted or electric only. In addition, the unit will have multiple ways to charge the locomotive batteries, including regenerative braking, wayside charging, and onboard charging. The “Mother-Slug” configuration replaces the two locomotives with one prime mover locomotive called the “Mother” and a connected accessory called a “Slug” that is controlled by the mother to provide additional horsepower or braking when required. 

In keeping with its sustainability commitments, Union Pacific will retrofit older slug locomotives with higher emissions into rechargeable energy storage systems with electric drives using batteries, energy management systems and advanced control systems provided by ZTR. As a result, the battery-electric powered slug will reduce fuel consumption and maintenance costs while delivering significant environmental benefits. 

Prototypes of the new Hybrid-Electric Locomotive is expected in late 2023.

Read the full release here.

Learn more about ZTR's environmental upgrades and solutions here.