EMD GP7
The EMD GP7 is a four-axle diesel-electric locomotives series of U.S. locomotive manufacturer General Motors Electro-Motive Division (EMD ) of the GP series.
With this series EMD came the requirements of the railway companies meet for a usable both in shunting and line services machine. Originally designed as a freight locomotives, some specimens were also used in passenger transport.
A total of 2,724 machines created with cab (A- units ) and 5 führerstand loose B units. The latter were exclusively ordered by the Santa Fe.
Development
The machines of the F- series initiated the replacement of steam locomotives in freight railways in North America. However, they were only suitable for the local freight with its extensive maneuvering. Through the front alignment of the cabs visibility was severely limited to the rear.
Just shunting was highly uneconomical steam locomotives, due to long service life and frequent starting. With competitors such as the American Locomotive Company ( ALCO) was a type of locomotive available, which eliminated exactly these criticisms. EMD had to follow suit. A first attempt to combine a more appropriate locomotive body with the mechanical equipment of the EMD F3, was not satisfactory in operation.
Was not until the year 1949 with the GP7 a competitive product to the Alco- models on the rails.
Construction
Technically, the GP7 based on the F7. Changes primarily impacted the housing form. According to the issued by chief engineer Dick Dilworth solution form follows function ( German: The shape is based on the application ) was a design especially like Dilworth put it, Christmas tree ornaments and other nonsense (English: " Christmas tree ornaments and other whimsy " ) deprived had.
The EMD GP7 had a stable framework, which was lined with doors. This provides a very wartungefreundliche design was created because all aggregates were easily accessible from the outside. The A- unit had a cab to which the machine could be in contrast to the series of the E and F series driven in both directions. Behind the engine room was with the traction generator which supplied the DC power to the traction motors and the diesel engine EMD 567B. The type designation EMD 567 means that the engine had a swept volume of 567 cubic inches. The vehicles of the early GP series had 16- cylinder engines.
The fuel tank was positioned between the bogies and took 4,542 liters of diesel oil. Along the engine cover a walkway for the shunter was arranged on both sides. So this could get from the cab directly to the two ends of the vehicle.
Equipment
On request, the machines were delivered with optional equipment. Many models come with a brake resistor. Here, the kinetic energy is converted by the traction motors in electric energy and this then generated via braking resistors heat. This causes the brake wear could be reduced because the dynamic brake operates without wear. To deliver the heat to the environment, the so -equipped locomotives had an additional roof vent, beginning with a diameter of 36 inches ( 914 mm). Later, the diameter of the fan to 48 inches was enlarged ( 1,219 mm). Locomotives with dynamic brake can be identified by the additional ventilation grille in the center of the vehicle.
Some machines were equipped with an additional boiler for train heating. This one use on passenger trains was possible. On machines with heating system, the boiler was installed in the short stem. This becomes clear from the additional exhaust system.