Milwaukee Road class A

The steam locomotives of the class A of the Milwaukee Road were the largest, most powerful and fastest Atlantic locomotives ( wheel arrangement 2'B1 ') that have ever been built. They were among the fastest steam locomotive in the world.

Formation

To establish the connection between Chicago and the Twin Cities of Minneapolis and St Paul competed three railway companies, the Chicago, Burlington and Quincy Railroad, the Chicago and North Western Railway and the Chicago, Milwaukee, St. Paul and Pacific Railroad, shortly Milwaukee Road. This compound was one of the busiest in the United States. The three routes were 694, 674 and 680 kilometers long, so that the travel time difference is not too much fell into the weight. In the early 1930s The trip lasted about 10 hours.

All three tracks aimed at speeding up the traffic, the superstructure of the routes has been improved and planned new trains. The end of 1934 was the Chicago & North Western rebuild some sets of express wagons, and twelve Pacific locomotives. The locomotives were able to pull the trains over long periods of time at 160 km / h and more, and the total distance an average of around 100 km / h was achieved. A few months later, the Burlington with a " Pioneer Zephyr" said diesel-electric high-speed railcars, which was still slightly faster and was regarded as America's fastest train.

The Milwaukee Road had to now do something to counter this competition. They decided against a railcar and a steam locomotive hauled train; the reasons for this was the greater flexibility in space that are not yet fully developed diesel technology, lower investment and greater safety in the event of a collision on a level crossing.

In ALCO finally two steam locomotives were ordered, which were designed in close collaboration with the chief engineer of the railway CH Bilty. The need for two sets of wagons 12 four-axle express passenger cars built the Milwaukee Road in its own railway workshops. As a name for the new train was chosen " Hiawatha ", after the legendary Indian chief Hiawatha flinkfüßigen.

The construction and production of the two locomotives lasted only a few months, and on 30 April 1935, the first machine was presented to the public at a ceremony for the first time. The second followed a few days later. A prime horses of the Milwaukee Road, they received the track numbers 1 and 2

Technology

The class A was significantly larger than the previously largest and most powerful of the Atlantics in 1914 -built Class E6s the Pennsylvania Railroad, and the permissible axle loads allowed a friction weight of 642 kN ( 65.5 t). That was more than did European Pacific locomotives, and was perfectly adequate for the intended draw weight of about 320 tons. The waiver of a third coupled axle reduced the friction of the engine and especially the reciprocating engine mass. Also contributed to the relatively high pressure of the boiler of 300 psi ( 20.7 bar), which allowed the use of relatively small cylinder and piston, and also passed driving and coupling rods of high alloy steel, so that here weight could be saved. Unlike most previous Atlantics the rods worked to the first attachment pin, which had a relatively great distance from the bogie.

Despite the high speeds, provided you gave up a three-cylinder engine. In the U.S., this engine type was very rare; the main reason was the poor accessibility of the inner cylinder and the larger maintenance costs associated with it.

The vehicles had a continuous cast steel frame with cast cylinders. Also the floor of the tender was a steel casting. All wheel sets of the locomotive and tender were running in roller bearings.

The designed by Otto Kuhler streamlining with very clear lines for American standards covered almost the entire locomotive. Only the lower half of the large drive wheels could be seen, as the lower edge of the panel was approximately level with the wheel center.

The locomotives were fired with oil. The five-axis Tender could hold 15 cubic meters of oil and 49 cubic meters of water, with the oil reservoir for the entire planned route was sufficient. The front bogie of the tender was triaxial, biaxial and the rear was similar in design to those of the express wagon. The cross section of the tender corresponded to the cars attached, so that a good optical transition between the locomotive and train of cars was given. The transition between the locomotive and tender are not interrupted the clean lines.

Speed

The work carried out at the beginning of May 1935 test drives the locomotive reached effortlessly laid down speeds. In a test run on May 15, 181 km / h were achieved. Thus, the Class A was for about a year - until the record-breaking run of 05 002 German on May 11, 1936 - officially the fastest steam locomotive in the world.

The speed of 181 km / h may have had in 1893 reached the No. 999 of the New York Central Railroad. Other than these, however, the locomotive Class A could maintain the daily operation and also for a long time that speed. In practice, the locomotives were even much faster. Regularly, the 120 - mph speed limit also unofficially referred to values ​​up to 130 mph ( 209 km / h ) is exceeded (193 km / h), and do not appear totally unrealistic in view of the construction of locomotives. If these details, then include the Class A locomotives in addition to the duplex locomotives of the Pennsylvania Railroad ( classes S1 and T1) to the fastest steam locomotives ever.

Use

On May 29, 1935, the scheduled operation began. The " Hiawatha " was now about six and a half hours of driving the fastest connection between Chicago and Minneapolis -St. Paul. The schedule called for on the open road speeds of at least 160 km / h, what the locomotives in everyday use coped easily.

The " Hiawatha " therefore was a complete success, and the passenger numbers rose. More cars were built, and in 1936 a third locomotive was put into service in 1937 and a fourth. But starting off with the increasingly heavy trains piled up so that as early as 1937, had to be purchased only two years after the introduction of the " Hiawatha ", larger and more powerful locomotives. It was Hudson locomotives ( wheel arrangement 2'C2 ', class F7)., This, however, ran more jagged than the Atlantics, despite equally large driving wheels at high speeds and therefore did not reach their top speed.

As the tension of the Class A was no longer sufficient for the main lines, they were used along with their car sets for the " Midwest Hiawatha ." But a short time later to diesel locomotives prevailed, and 1949, the number 3 and 1951, the other three locomotives were scrapped. All four specimens were scrapped. Unlike many other streamlined locomotives they had retained her disguise until the end.