Milwaukee Road class F6
Encyclopedia
The Milwaukee Road classes F6 comprised twenty-two steam locomotive
Steam locomotive
A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...

s of the 4-6-4
4-6-4
Under the Whyte notation for the classification of steam locomotives, 4-6-4 represents the wheel arrangement of four leading wheels on two axles , six powered and coupled driving wheels on three axles, and four trailing wheels on two axles .Other equivalent classifications are:UIC classification:...

 configuration, commonly nicknamed “Hudson” but known as “Baltic” on the Milwaukee Road. They would have been the first 4-6-4 tender locomotive
Tender locomotive
A tender or coal-car is a special rail vehicle hauled by a steam locomotive containing the locomotive's fuel and water. Steam locomotives consume large quantities of water compared to the quantity of fuel, so tenders are necessary to keep the locomotive running over long distances. A locomotive...

s in the world were it not for the Milwaukee's financial difficulties which culminated in bankruptcy in 1925.

The fourteen class F6 locomotives were not delivered from their builder, the Baldwin Locomotive Works
Baldwin Locomotive Works
The Baldwin Locomotive Works was an American builder of railroad locomotives. It was located in Philadelphia, Pennsylvania, originally, and later in nearby Eddystone, Pennsylvania. Although the company was very successful as a producer of steam locomotives, its transition to the production of...

 of Philadelphia, Pennsylvania
Philadelphia, Pennsylvania
Philadelphia is the largest city in the Commonwealth of Pennsylvania and the county seat of Philadelphia County, with which it is coterminous. The city is located in the Northeastern United States along the Delaware and Schuylkill rivers. It is the fifth-most-populous city in the United States,...

, until 1929–1930. In 1931, eight sister locomotives of class F6-a were delivered; these differed in few aspects but can be distinguished by the straight running boards of the F6-a, in contrast to the stepped running boards of the F6.

Technical details

The 1925 design was by Milwaukee Road Chief Mechanical Engineer C. H. Bilty, with detail design by the Baldwin Locomotive Works
Baldwin Locomotive Works
The Baldwin Locomotive Works was an American builder of railroad locomotives. It was located in Philadelphia, Pennsylvania, originally, and later in nearby Eddystone, Pennsylvania. Although the company was very successful as a producer of steam locomotives, its transition to the production of...

, who actually built them. They represented the best of American locomotive practise at the time, and were given all the latest devices and fittings. A Coffin feedwater heater
Feedwater heater
A feedwater heater is a power plant component used to pre-heat water delivered to a steam generating boiler. Preheating the feedwater reduces the irreversibilities involved in steam generation and therefore improves the thermodynamic efficiency of the system...

 was fitted, which was the Milwaukee's favorite type; this was installed flush in the extended smokebox
Smokebox
A smokebox is one of the major basic parts of a Steam locomotive exhaust system. Smoke and hot gases pass from the firebox through tubes where they pass heat to the surrounding water in the boiler. The smoke then enters the smokebox, and is exhausted to the atmosphere through the chimney .To assist...

, and thus was not at all obvious. Possibly because of this, the boiler lagging
Lagging
Lagging may refer to:* Thermal insulation* Lagging * Lagging indicator * Lag...

 was continued over the smokebox, which was not common; most North American locomotives had bare smokeboxes which were graphited, rather than painted. The associated steam-driven centrifugal water pump
Boiler feedwater pump
A boiler feedwater pump is a specific type of pump used to pump feedwater into a steam boiler. The water may be freshly supplied or returning condensate produced as a result of the condensation of the steam produced by the boiler...

 was located under the cab at the left rear. The class F6-a was fitted with the tender-mounted Wilson Water Conditioner instead of the Coffin feedwater heater.

Valve gear
Valve gear
The valve gear of a steam engine is the mechanism that operates the inlet and exhaust valves to admit steam into the cylinder and allow exhaust steam to escape, respectively, at the correct points in the cycle...

 was of the low-maintenance Baker
Baker valve gear
Baker valve gear was the main competitor to Walschaerts valve gear for steam locomotives in the United States. Strictly speaking it was not a valve gear but a variable expansion mechanism adapted to the Walschaerts layout replacing the expansion link and sliding die block...

 type, with (of course) power reverse. A front-end throttle was installed, with the distinctive linkage running along the boiler on the engineer's side. A mechanical lubricator, driven from the crosshead on the engineer's side, fed oil to the cylinders, valves, guides and other parts of the running gear. Many of the locomotives were fitted with a speedometer, which was attached to the engineer’s side frontmost leading axle.

A single air pump for the locomotive and train air brakes
Air brake (rail)
An air brake is a conveyance braking system actuated by compressed air. Modern trains rely upon a fail-safe air brake system that is based upon a design patented by George Westinghouse on March 5, 1872. The Westinghouse Air Brake Company was subsequently organized to manufacture and sell...

 was fitted to the fireman's (left) side, with air tanks under the running boards on both sides. Like all larger North American coal-burning locomotives of the time, an automatic stoker was fitted; the two-cylinder engine to drive this was under the cab floor on the fireman's side.

Modifications

Locomotive #6401 received large, "Elephant ear" smoke deflectors in 1936 as an experiment; these were kept for several years, but were not fitted to other locomotives. Later that year a sheet-steel pilot
Pilot (locomotive)
In railroading, the pilot is the device mounted at the front of a locomotive to deflect obstacles from the track that might otherwise derail the train. In some countries it is also called cowcatcher or cattle catcher....

 was fitted to it and several other locomotives to replace the boiler-tube pilot installed from new. This featured a swing-up coupler. As well as giving a more attractive, streamlined look, this had a serious safety aspect; a sheet-steel pilot without a protruding coupler was more likely to deflect an obstacle without catching on it in e.g. a grade crossing accident.

Service

At first the locomotives were used mostly between Chicago and Minneapolis, but later on when the F6-a locomotives arrived they served as far west as the beginning of the electrified zone.

Speed record

On July 20, 1934, Milwaukee Road class F6 Baltic #6402 participated in a test run to prove the feasibility of a high-speed service, which was launched as the Hiawatha
Hiawatha (passenger train)
The Hiawathas were named passenger trains operated by the Chicago, Milwaukee, St. Paul and Pacific Railroad , and traveled from Chicago to the Twin Cities in Minnesota. The original train takes its name from The Song of Hiawatha by Henry Wadsworth Longfellow...

 service in 1935. The test used a regular service train from Chicago, Illinois to Milwaukee, Wisconsin
Milwaukee, Wisconsin
Milwaukee is the largest city in the U.S. state of Wisconsin, the 28th most populous city in the United States and 39th most populous region in the United States. It is the county seat of Milwaukee County and is located on the southwestern shore of Lake Michigan. According to 2010 census data, the...

, train 29. This was redesignated as Second 27 just for that day and given a special, high-speed timing. With a five-car train of 840000 pounds (381 t), #6402 completed the 85 miles (136.8 km) in 67 minutes and 37 seconds start to stop. The eventual Hiawatha timing was 75 minutes for this journey, and the Hiawatha timing was possibly the fastest scheduled train in the world in the 1930s.

While the ends of the trip were taken at relatively low speeds, the 68.74 miles (110.6 km) between the Chicago suburb of Mayfair and Lake, Wisconsin
Lake, Wisconsin
Lake is the name of some places in the U.S. state of Wisconsin:*Lake, Marinette County, Wisconsin, a town*Lake, Milwaukee County, Wisconsin, a former town*Lake, Price County, Wisconsin, a town...

was completed in 45 minutes and 53 seconds, an average of 89.89 mph (40.2 m/s). Times were taken with a stopwatch as each station was passed, and in addition the locomotive was fitted with a speedometer; this recorded the speed on a chart, indicating a maximum of 103.5 mph (46.3 m/s) was reached. The fastest inter-station average speed was 95.6 mph (42.7 m/s) between Oakwood and Lake; British expert Brian Reed showed that the latter half of that was an uphill gradient and thus speeds in the first half must have been significantly higher than the overall average. He stated that:
This must be taken as the first time a U.S. steam loco topped "the hundred".


More recently, British train timer Bryan Benn has taken the gradient profile given in Brian Reed's book and shown that it supports a maximum speed in excess of 101 mph during that portion of the run. He believes this is the first claim of over 100 mph (44.7 m/s) for a steam locomotive in which the surviving documentation strongly indicates its accuracy, and thus that #6402 was the record holder for steam locomotive speed for at least a short time.
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