News & Reviews News Wire Union Pacific unveils first mother-slug set of hybrid switchers (with video)

Union Pacific unveils first mother-slug set of hybrid switchers (with video)

By Bill Stephens | April 29, 2024

The locomotives can run on batteries or in conventional diesel-electric modes

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Union Pacific’s first set of mother-slug hybrid switchers were unveiled on April 29, 2024. UP

OMAHA, Neb. — Union Pacific today took the wraps of its first mother-slug set of hybrid switching locomotives that can run on diesel fuel or batteries.

The units, SD40-2 slug set UPY No. 409 and UPY No. 309, were converted at the railroad’s Jenks Locomotive Shop in North Little Rock, Ark., and will begin testing in North Little Rock next month.

“This is an incredibly exciting pilot project with great potential to improve the fuel efficiency of our locomotive fleet,” UP President Beth Whited said in a statement today (April 29, 2024). “It underscores our strong commitment to exploring and developing alternative energy sources while reducing our carbon footprint and advancing our sustainability goals.”

Depending on mode of operation, the hybrid switchers are expected to consume as much as 80% less fuel — reducing associated greenhouse gas emissions and pollutants. Additional benefits include reduced maintenance expense and noise compared to traditional diesels.

The set is the first of six being built using energy control systems from tech company ZTR under an agreement announced in 2022 [see “Union Pacific to partner on construction of hybrid-electric locomotives,” Trains News Wire, Oct. 6, 2022]. It relies the mother locomotive running on diesel and the slug providing battery power. The batteries can plug in for charging or recharge while in use.

“We are excited about the groundbreaking hybrid technology built in partnership with Union Pacific. Union Pacific is serious about reaching their sustainability goals and they have been an outstanding partner in this project,” said ZTR President Sam Hassan. “The development of the ZTR BLU Technology platform is one of the most significant projects for ZTR to date and will be the basis for further advancements in sustainable solutions, including emission-free locomotives.”

Union Pacific began rolling out mother-slug sets with ZTR’s Nexsys control systems in 2017 and currently operates more than 65 in yards systemwide.

“This is a huge step forward in zero-emission technology. It’s extremely cutting edge, and one of the coolest things I’ve worked on in my career,” said Jason Fox, UP’s senior director-locomotive engineering and quality, said in a statement. “If all goes well, we may someday use this technology in all of our rail yards as a switcher set used to build trains.”

UP also has committed to purchasing 20 battery-electric switchers, with the order split between Wabtec and Progress Rail, and is testing higher blends of biodiesel in its fleet.

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