Milwaukee Road class EP-2
For class EP-2 "Bi- Polar" the Chicago, Milwaukee, St. Paul and Pacific Railroad (Milwaukee Road) is of ALCO and General Electric developed for passenger traffic in the Cascade Range electric locomotives. Five vehicles were built in 1919 and 1920. First you got the track numbers 10250-10254 and were later redrawn in E-1 to E-5. They were in the 40 years of service, a hallmark for the Milwaukee Road and made a landmark in the history of the electric drive of railway vehicles.
Construction
The locomotives with 12 drive and two drive axles are unique in their design. The wheel arrangement is specified after the American spelling with 1B D D B1, according to European notation 1'Bo ' Do' Th ' BO'1 '. That is, the locomotive has a drive of four mutually articulated frames that transfer the train and impact forces. Each is a frame with a duration of the Lokenden and two driving axles, which is also provided with the coupling inside the two frames, each four driving axles.
The locomotive body, which does not transmit any longitudinal forces, consists of three parts. The two end with the characteristic barrel-shaped structure are fixed to the respective underlying four-axle frame and based on sliding parts on the end frames from. This is reminiscent of the European Crocodile locomotives short middle section is carried by the two end portions and thus is not directly connected to chassis components. In the middle part is the steam boiler for train heating; the electrical equipment operated with 3000 V DC locomotives is housed under the round hoods. This was the move away from the box-shaped boxcab design that characterized the only two to four years older predecessor series EP-1. The Milwaukee Road was the only North American railway company, to General Electric, this type of joint locomotives surrendered.
The real peculiarity of the EP-2 is the simple version of the motors. On the axis of each of the spring-loaded drive wheel of the rotor of a DC motor is mounted, while the windings of the respective stator fixed to the front locomotive frame and positioned behind the respective axis, and thus only two pole could be carried out, which is due also naming bi- polar.
In contrast to the other then usual drives, this neither variant reduction gear still used rods for transmitting the driving forces, which is why the locomotive in comparison with other former types up to a speed of about 15 km / h were barely audible. Only then began the hum of the engines. The top speed was officially at about 113 km / h (70 mph) - but there were up to 130 km / h can be achieved.
The disadvantage was the poor efficiency due to the need for the Radsatzfederung large air gap, as well as the unfavorable two-pole motor design with low speed, so 12 powered axles were necessary for the performance, which had the lower American standards axle load of 17.3 tonnes. The type of the drive was used except for the EP -2 of the Milwaukee only to locomotives of the S-Class of the New York Central Railroad.
Use
As per the $ 200,000 expensive locomotives on the Coast Division were used, they were quickly recognized by its modern and unique design for marketing purposes, in particular for the showpiece Olympian. In a high-profile " tug of war " was allowed an EP - 2 on a truss bridge their force against two steam locomotives - a Mallet ( ( 1'C ) C1 ' ) and Consolidation ( 1'D ) - flaunt. In a brief attempt to use the more eastern Mountain Division showed that the locomotives were cheaper to operate than the locomotives used at the time of the parallel rows of EP-1 and EP- third In the regular passenger train service between Tacoma and Othello could be dispensed over the fabric with steam locomotives on operational intermediate stops and done the ride on slope portions without double covering.
In 1952 the locomotives for each $ 40,000 were modernized. They were among other multiple unit control. Also, the ends of the stems were rounded, which the locomotives made it look more modern. The conversion by the inexperienced with electric locomotives workshops of the Milwaukee Road, however, increasingly led to fires and electrical malfunctions. As of mid- 1957, the locomotives were transferred from the Coast Division of the Mountain Division and placed progressively from 1958 out of service. In 1960, all off. A locomotive ( the E-2, ex- 10251 ) is on display at the National Museum of Transport in St. Louis, the others were scrapped.