Sold in 1906 to the Lackawanna & Wyoming Valley Railroad in northern Pennsylvania as a 600 hp (450 kW) 500 V DC locomotive, it was in service until 1953.
Electrification of the busy main line would increase the capacity of the existing four tracks.
But New Haven chose single-phase AC as proposed by Westinghouse, at 11 kV 25 Hz.
They had to operate over the 12 miles of New York Central track electrified at 660 V DC third rail from Grand Central to Woodlawn, so had AC/DC series commutator motors; the four Westinghouse 130 motors had a total hourly rating of 1,420 hp (1,060 kW).
The locomotive could change from AC to DC without stopping; power pickup was by eight third-rail shoes which could be lowered, plus two large AC pantographs and a small pantograph for DC where short sections through switches were too complicated for third-rail supply.
A second order of six supplied in 1908 had design changes, including guide wheels at each end to obviate "nose" or oscillation at high speed.
[4] In 1910 New Haven decided to extend electrification, and to electrify freight and switching as well as passenger service.
Similar to the 1912-1913 locomotives, they were 69 foot long and weighed 175 tons, with a top speed of 70 mph (110 km/h).
These were delivered in the 1920s to provide freight service within the city, serving mainly the General Motors plant.
[10] One example bearing number 300 from Oshawa is preserved at the Seashore Trolley Museum.
They were AC only, weighed 246 tons, and rated 4860 hp with a tractive effort of 90,000 lb.
Each Z-1 locomotive had two semi-permanently coupled 1-D-1 box-cab units; the pair weighed more than 371 tons with an hourly rating of 4330 hp and a continuous tractive effort of 88,500 lbs per unit (177,000 lb per pair) and a maximum starting effort of 189,000 lb.