Great Northern boxcab (3 phase)

Great Northern Boxcab (3-Phase)
Three Great Northern boxcabs
Type and origin Power type Electric Builder GE and ALCO Build date 1909
Specifications Configuration: ​  • AAR B-B  • UIC Bo′Bo′ Gauge 4 ft 8+1⁄2 in (1,435 mm) standard gauge Wheel diameter 60 in (1.5 m) Length 44 ft 2 in (13.46 m) Width 10 ft 0 in (3.05 m) Loco weight 230,000 lb (100,000 kg; 100 t) Electric system/s 6.6 kV, 25 Hz AC (3-Phase) Current pickup(s) Pantograph Traction motors 4 × GE-1506 Gear ratio 19/81
Performance figures Maximum speed 15 mph (24 km/h) Power output 1,500 hp (1,100 kW) Tractive effort: ​  • Starting 57,500 lbf (256 kN) at 25% adhesion  • 1 hour 38,000 lbf (170 kN)  • Continuous 34,800 lbf (155 kN) Factor of adh. 25%
Career Operators Great Northern Railway Number in class 4 Numbers 5000–5003 Delivered 1909

The GN boxcab locomotives were the first electric locomotives purchased by the Great Northern Railway (GN) for use through the Cascade Tunnel. Four locomotives were supplied by the American Locomotive Company; they used electrical equipment from General Electric and weighed 115 short tons (104 t) each..

They were three-phase electric locomotives producing 1,500 hp (1,100 kW) each. The specification called for 1000hp, but the actual output was substantially greater, as described by the consultant engineer Cary T. Hutchinson. They had a B-B wheel arrangement. They were built in February and March 1909, and delivered in Pullman Green. The GN numbered them 5000–5003 and they were used until May 1927.

Initially three locomotives were coupled together and hauled trains at a constant speed of 15.7 mph (25.3 km/h), but when larger trains required four locomotives the motors were concatenated (cascade control), so that the speed was halved to 7.8 mph (12.6 km/h) to avoid overloading the power supply.