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Union Pacific Motor Cars

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This page was last updated on July 27, 2013.

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Roster Listing

Motor Car Roster — A roster of Union Pacific's motor cars, including the McKeen cars, the EMC cars, the Brill cars, and the cars that UP itself built.


(from the book, "Union Pacific Diesels, 1934-1982, Volume 1" by Don Strack)

The first internal-combustion rolling stock on UP was a series of self-propelled McKeen passenger cars, powered by small gasoline and distillate-fueled engines. These motor cars were designed by UP's superintendent of motive power and machinery, William McKeen, and were built beginning in 1905 by UP in the railroad's Omaha, Neb., shops. In 1908, UP organized the McKeen Motor Car Co. as a subsidiary to sell McKeen cars to other railroads, and production continued in the Omaha shops. With their distinctive wedge-nosed front ends, these cars were designed and operated as self-contained passenger trains, but by 1909, they were powerful enough to pull a trailer.

Competition for McKeen's mechanical-transmission motor cars came in 1911 when General Electric released its own design for an electric-transmission motor car. McKeen's largest vehicle, a rounded-front 300-horsepower car with a three-axle power truck, was completed in 1916 as a demonstrator for Southern Utah Railroad in Utah's Carbon County coal fields (it was delivered on January 1, 1917). The last McKeen cars were completed in 1917, which was also GE's last year for motor-car production. The production of motor cars ceased with the United States' entry into World War I. By 1920, McKeen's mechanical-transmission car had lost sufficient interest among potential customers that UP bought full control of McKeen and formally stopped production. Union Pacific completed several motor cars for itself during mid-1923, using the remaining McKeen bodies.

A growing interest for electric-transmission motor cars after the war led to the formation of Electro-Motive Corp. in 1922 to again market gas-electric motor cars to America's railroads, taking advantage of better and more powerful engines and better electrical control. In 1927, UP began buying Electro-Motive motor cars, receiving 15 cars during 1927 and 1928. Also in 1928, UP acquired two motor cars from Brill, and another two came from Brill in 1930. Several of the mechanical McKeen cars were converted to gas-electrics during the 1920s, and the last mechanical McKeen cars were retired in 1942. Electric-transmission motor cars with both gasoline engines and distillate engines remained in service on UP throughout the 1940s and 1950s, with the last one being retired in 1961.

Between 1920 and 1932, the number of passenger-miles for America's railroads had dropped by two-thirds, inversely matching the tripling of automobile registrations during the same period. The public wanted faster schedules and more comfort. To furnish faster schedules, Union Pacific needed either lighter trains or more powerful locomotives. UP chose to pursue a lighter train, based on its experience with self-propelled motor cars, with their electric transmissions and increasingly powerful distillate engines during the late 1920s. Lighter trains would also spring from developments in lightweight metals during the post-World War I years, and from aerodynamic designs for rail equipment (specifically, Pullman's Railplane of March 1933). More comfort, especially for business and upscale pleasure travelers, would come with new, more modern designs. These developments led Union Pacific in 1933 to ask for the development of the lightweight, articulated passenger train, which became known as The Streamliner. Union Pacific saw The Streamliner as the answer to what the traveling public wanted, and the first Streamliner was M-10000.

System Repair Shop

A new engine house was constructed at Grand Island, Neb., in 1910, and at that time, Grand Island "became the major system repair point for a growing fleet of passenger motor cars. The motor cars continued to be repaired at Grand Island until the last of them were retired." (The Streamliner, Volume 2, Number 2, April 1986, page 21)

Using Distillate Fuel

(click here for more information about distillate fuel)

Union Pacific and other railroads were always looking to reduce costs, and "distillate" fuel was much cheaper than gasoline. Industry standards in the 1920s were not anything close to what we have now, so distillate fuel was essentially whatever the refiners said it was, and the quality of it varied considerably. The major motivation for the use of distillate fuel was cost. The price of distillate fuel was one-third to one-fourth the price of gasoline, which was about 15 cents per gallon in those days.

In the 1954 biography of Dick Dilworth, EMC's chief engineer, the author wrote about Dilworth's five-year search that began in 1927, "First of all, Dilworth had to discover what a distillate was. About the best definition he could arrive at was that it was anything that didn't classify as heavy fuel oil. It might range from a low-grade gasoline, to painter's naphtha, to gas oil. In fact it was anything the refinery didn't happen to want at that particular time. The most uniform product Dilworth came across was something known as Dubbs oil, the heavy half of the pressure benzene taken off during the Dubbs cracking process. Attempting to burn this stuff in a carburetor engine, according to Dilworth, was grim business."

After five years of work in the lab, and in test installations, in 1932 Dilworth was finally able to figure it out, and patented a carburetor that allowed distillate to be used in the Winton engines used in the EMC motor cars.

When Union Pacific began using distillate fuel in about 1926-1927, they used what was known as a Duff carburetor, using the design patented by Ralph Duff in 1918. Prior to that time, UP used gasoline in its motor cars.

Using resources available today, the most common and credible modern equivalent of distillate fuel today is what is called No. 2 fuel oil, also known as home heating oil, or furnace oil.

Miscellaneous Notes

Letter to the editor, concerning a photo in an issue of The Streamliner (Volume 14, Number 1, Winter 2000, page 10):

The photo shows a view of McKeen motor car M-23. The caption suggests that the photo was taken during a run to evaluate some device mounted to the front truck. That may be true, but I think that what it really shows is M-23 on its first trip west. Notice how shiny the car and trailer are (sticky fresh, as some would say). The photo is dated May 17, 1915. Available records show that M-23 was built in May 1915.

This photo is unique because it shows the first use of the M prefix to the motor cars, since M-23 was the first car built after the 1915 renumber plan was put into place. All of the cars built before that time, from UP 1 (in 1905) to UP 22 (in 1909), were later renumbered to their M series numbers.

In the Spring 2001 issue of The Streamliner, Don Lodge wrote a letter to the editor:

"The McKeens were gas mechanical and thus cannot be considered direct predecessors of the early Streamliners. In fact, the McKeen cars might be thought of as one of a number of dead ends in the history of self-propelled rail cars."

"The first Union Pacific gas electric cars came in 1927. These were M-29 and M-30, built in the company shops from unused McKeen parts, and M-31 to M-35, built by St. Louis Car for EMC. According to Keilty, the shop-built "McKeens" utilized four unused car sides, Hall-Scott gas engines, and electrical components from General Electric. It was the electrical parts from GE that were critical to these cars' success."

"GE's pioneering work in designing a method of tieing together the control of a gasoline engine and an electric generator led to the modern day diesel locomotive."

Union Pacific purchased full control and interest of the McKeen Motor Car Company in March 1920. (Associated Press, Kingsport Times, September 5, 1922)

McKeen Patents

William Riley McKeen held several patents for designs used on his motor cars.

McKeen also filed a patent for a weed cutter for railway equipment, Patent 830,163, dated September 4, 1906

Motor Cars In Utah

(incomplete; more to be added)

July 1911
OSL began using a 100-passenger motor car for service on the Cache Valley branches. To connect with through trains that ran through Cache Junction, one round trip was made between Cache Junction and Preston, Idaho, each day, and two round trips were made between Cache Junction and Logan each day. The motor train operation was in addition to regular steam trains which continued to make their scheduled truns. (Box Elder County News [Brigham City], July 27, 1911)

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