NRE 3GS21B

Specifications
Specifications
Gauge	4 ft 8+1⁄2 in (1,435 mm)
Prime mover	Cummins QSK19C (×3)
Engine type	Diesel engine (×3)
Aspiration	Turbocharger (×3)
Cylinders	6 (×3)

Type and origin
Type and origin
Power type	Diesel-electric
Builder	National Railway Equipment (NRE)
Model	3GS21B
Build date	December 2006 – Present
Total produced	182

NRE 3GS21B
NRE 3GS21B
	A new NRE 3GS21B locomotive in the Union Pacific scheme.
Power type
Type and origin
Power type	Diesel-electric
Builder	National Railway Equipment (NRE)
Model	3GS21B
Build date	December 2006 – Present
Total produced	182
Gauge
Specifications
Gauge	4 ft 8+1⁄2 in (1,435 mm)
Prime mover	Cummins QSK19C (×3)
Engine type	Diesel engine (×3)
Aspiration	Turbocharger (×3)
Cylinders	6 (×3)
Power output
Performance figures
Power output	2,100 hp (1,570 kW)
Operators
Career
Operators	See list

The NRE 3GS21B is a low-emissions diesel genset locomotive built by National Railway Equipment (NRE). Instead of a single prime mover, the NRE genset locomotive is powered by three separate 700 horsepower (522 kW) Cummins QSK19C engines providing a total power output of 2,100 horsepower (1,570 kW). Each engine could be individually started or shut off depending on how much power is needed, reducing overall diesel emissions and improving fuel efficiency. More than 150 of the 3GS21B genset locomotives have been produced to date, with the majority of these units being manufactured at NRE's Mount Vernon shops in Southern Illinois. In addition, three road slug models have also been produced. The main difference between this and the NRE 3GS21C is that these units are on B-B (four wheel) trucks and the others are on C-C (six wheel) trucks.