National Museum of Transportation near Kirkwood in St. Louis County, Missouri — The American Midwest (Upper Plains)
What Does "Bi-Polar" Mean?
Photographed By Devry Becker Jones (CC0), April 22, 2019
1. What Does "Bi-Polar" Mean? Marker
Inscription.
What Does "Bi-Polar" Mean?. . This electric locomotive uses a drive system that eliminates the gearing normally used between the motor and axle. It does this by making the axle part of the motor itself. The armature of the motor is mounted on the axle, and the motor's poles and magnetic fields are mounted on the frames next to them. As there were two of these field magnets per motor the term "bi-polar" came to be used. The geared electric drives of the period were limited by the large size of the motors needed for mainline locomotives. They were difficult to fit into the space available between the frames and next to the wheels. The "bi-polar" avoided this problem although it had a considerable amount of weight not cushioned by its springs. They operated for long and successful careers, but the development of lighter and more compact motors made geared designs universal after world war two. The Milwaukee Road's "bi-polar" was a passenger locomotive. It could haul a 1000-ton train of a dozen steel cars up a 2.2% grade ( arise of 2. feet for every 100 feet of distance) at 25 mph wihtout a helper locomotive, or speed it along at 60 mph on level track. Its maximum safe speed was 65 mph. It ran on 3,000 volts of direct current power. It has 12 motors to drive its 44" wheels, and only the end axles with 36" wheels are not powered. It produced 3,517 HP for short periods. It is 76' long and weighs 521,000 lbs. New York Central #113, on exhibit nearby, also uses the same "bi-polar" drive, but uses 660-volt D.C. power.
This electric locomotive uses a drive system that eliminates the gearing normally used between the motor and axle. It does this by making the axle part of the motor itself. The armature of the motor is mounted on the axle, and the motor's poles and magnetic fields are mounted on the frames next to them. As there were two of these field magnets per motor the term "bi-polar" came to be used. The geared electric drives of the period were limited by the large size of the motors needed for mainline locomotives. They were difficult to fit into the space available between the frames and next to the wheels. The "bi-polar" avoided this problem although it had a considerable amount of weight not cushioned by its springs. They operated for long and successful careers, but the development of lighter and more compact motors made geared designs universal after WW II. The Milwaukee Road's "bi-polar" was a passenger locomotive. It could haul a 1000-ton train of a dozen steel cars up a 2.2% grade ( arise of 2. feet for every 100 feet of distance) at 25 mph wihtout a helper locomotive, or speed it along at 60 mph on level track. Its maximum safe speed was 65 mph. It ran on 3,000 volts of direct current power. It has 12 motors to drive its 44" wheels, and only the end axles with 36" wheels are not powered. It produced 3,517 HP for short periods. It is 76'
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long and weighs 521,000 lbs. New York Central #113, on exhibit nearby, also uses the same "bi-polar" drive, but uses 660-volt D.C. power.
Location. 38° 34.263′ N, 90° 27.792′ W. Marker is near Kirkwood, Missouri, in St. Louis County. It is in National Museum of Transportation. Marker can be reached from Barrett Station Road east of Old Dougherty Ferry Road, on the right when traveling east. Touch for map. Marker is at or near this postal address: 3015 Barrett Station Road, Saint Louis MO 63122, United States of America. Touch for directions.
Other nearby markers. At least 8 other markers are within walking distance of this marker. #1057 (here, next to this marker); #1 (here, next to this marker); #E-2 (a few steps from this marker); #1149 (a few steps from this marker); #884 (a few steps from this marker); #13889 (a few steps from this marker); #724 (a few steps from this marker); #1082 (a few steps from this marker). Touch for a list and map of all markers in Kirkwood.
Photographed By Devry Becker Jones (CC0), April 22, 2019
2. What Does "Bi-Polar" Mean? Marker
Credits. This page was last revised on April 24, 2020. It was originally submitted on April 28, 2019, by Devry Becker Jones of Washington, District of Columbia. This page has been viewed 110 times since then and 10 times this year. Photos:1, 2. submitted on April 28, 2019, by Devry Becker Jones of Washington, District of Columbia.
