EMD SD7
| EMD series SD7 various railway companies |
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|---|---|
 EMD SD7 of the Southern Pacific Railway # 1518
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| Manufacturer: | Electro-Motive Division |
| Year of construction (s): | 1952-1953 |
| Axis formula : | Co'Co ' |
| Gauge : | 1435 mm ( standard gauge ) |
| Service mass: | 152.7 t |
| Top speed: | 105 km / h |
| Hourly output : | 1,100 kW |
| Motor type: | EMD 567 B, 2-stroke diesel |
| Power transmission: | electric |
| Number of traction motors: | 6th |
The EMD SD7 is a series of 6-axle diesel-electric locomotives from the US locomotive manufacturer General Motors Electro-Motive Division (EMD).
A total of 118 vehicles of this series were built in the EMD workshops in La Grange, Illinois .
development
With the introduction of the GP7 in 1949 , a machine was available that met the requirements of the railway companies in terms of track service and maneuverability . However, with an axle load of 28 tons , these machines were too heavy for some routes. So the idea arose to create a machine with a lower axle mass by extending the GP7 and using three-axle bogies . These considerations led to the delivery of the SD7 series in 1952.
However, due to the higher number of traction motors , the machines were more expensive to buy and maintain than the GP7. As a result, the sales of the early SD series models lagged behind those of the GP series .
construction
The SD7 was technically based on the successful GP7 series. By the longer bogies also had locomotive frame are stretched. The EMD SD7 had a stable frame, which was covered with doors. This created a very maintenance-friendly design, as all units were easily accessible from the outside. The series had a driver's cab with which it could be driven in both directions , in contrast to the machines of the E and F series . Behind it was the engine room with the traction generator , which supplied the direct current for the traction motors, and the EMD 567 B diesel engine . The EMD 567 type designation means that the engine had a displacement per cylinder of 567 cubic inches. The vehicles of the early SD series had 16- cylinder engines.
The fuel tank was arranged between the bogies and held approx. 4,500 liters of diesel oil . A walkway for the shunter was arranged along both sides of the engine casing. This enabled him to get directly from the driver's cab to both ends of the vehicle.
equipment
Many models were supplied with a resistance brake at the customer's request . Here, the kinetic energy is converted into electrical energy by the traction motors and then used to generate heat via resistance elements. As a result, the brake wear could be reduced, since the drag brake works largely wear-free. The locomotives equipped in this way had an additional roof fan to transfer the heat to the environment. In the photo of the SP 1518 on the right, the air inlet for cooling the resistors can be seen above the lettering 'Southern'.
literature
- Pinkepank, Jerry A .; The Second Diesel Spotters Guide; Kalmbach Publishing Co. Milwaukee; 4th edition 1980; ISBN 0-89024-026-4
