Union Pacific mother and slug

USA: Union Pacific and locomotive control technology supplier ZTR have agreed to co-operate on the production of diesel-battery hybrid locomotives, which can powered by a diesel engine or a battery back which would be charged using the engine or a lineside supply.

Primarily intended for use in yard shunting operations, the ‘mother and slug’ sets will be formed of a conventional diesel locomotive connected to a battery unit converted from an older diesel loco. This would retain its traction motors, but would have the prime mover replaced by a battery pack, with the power electronics and controls being supplied by ZTR. The hybrids are expected to offer fuel savings and greenhouse gas emission reductions of up to 80% compared with conventional diesels.

The locomotives are to be converted at UP’s workshops in North Little Rock, Arkansas, with a first prototype expected to be delivered in late 2023 and five more in 2024.

Union Pacific has been using diesel-powered mother-slug sets fitted with ZTR’s Nexsys control systems since 2017, and currently has more than 65 in service.

‘Adding hybrid-electric locomotives to our fleet is another important step for Union Pacific as we work to explore drop-in technologies that modify current systems and reduce our carbon footprint’, explained Senior Vice-President of Engineering & Mechanical Shane Keller on October 6. ‘This pilot will help make our fleet more fuel efficient and further advance our commitment to reaching our sustainability goals, while testing the technology’s capability for expanded use across our locomotive fleet.’

ZTR Control Systems President Derek Shipley said ‘this investment aligns well with our ongoing goal to leverage ZTR’s technical expertise to support railways in their decarbonisation and efficiency improvement efforts. This initial hybrid-electric mother-slug application will be the basis of our design for future hybrid-electric, long-haul and fully electric solutions.’