Milwaukee Road Class F6

The Milwaukee Road classes F6 and F6-a comprised twenty-two steam locomotives of the 4-6-4 configuration, commonly nicknamed "Hudson" but known as "Baltic" on the Milwaukee Road.
The fourteen class F6 locomotives were not delivered from their builder, the Baldwin Locomotive Works of Philadelphia, Pennsylvania, 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, who actually built them. They represented the best of American locomotive practice at the time, and were given all the latest devices and fittings. A Coffin feedwater heater was fitted, which was the Milwaukee's favorite type; this was installed flush in the extended smokebox, and thus was not at all obvious. Possibly because of this, the boiler lagging 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 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 was of the low-maintenance Baker 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 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 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. Sometime during the 30s or 40s, the F6s had air horns put on top of their boilers behind their smokestacks, much like the class F7 streamlined Baltics.
==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.
When delivered the class F6 were numbered 6400–6413, with the class F6-a numbered 6414–6421. At the 1938 renumbering, they were numbered 125–138 and 139–146
Table of locomotives
Original No.	1938 No.	Class	Baldwinserial No.	Built 	Retired
6400 	125 	F6 	61135 	January 1930 	June 1954
6401 	126 	F6 	61136 	January 1930 	December 1954
6402 	127 	F6 	61137 	January 1930 	February 1954
6403 	128 	F6 	61138 	January 1930 	February 1954
6404 	129 	F6 	61139 	January 1930 	December 1952
6405 	130 	F6 	61140 	January 1930 	December 1952
6406 	131 	F6 	61141 	January 1930 	September 1952
6407 	132 	F6 	61142 	January 1930 	October 1952
6408 	133 	F6 	61143 	January 1930 	October 1952
6409 	134 	F6 	61144 	January 1930 	July 1954
6410 	135 	F6 	61145 	January 1930 	September 1954
6411 	136 	F6 	61146 	February 1930	November 1954
6412 	137 	F6 	61147 	February 1930	December 1954
6413 	138 	F6 	61148 	March 1930 	December 1954
6414 	142 	F6-a 	61655 	October 1931 	December 1954
6415 	143 	F6-a 	61656 	October 1931 	December 1954
6416 	144 	F6-a 	61657 	October 1931 	December 1954
6417 	145 	F6-a 	61658 	October 1931 	December 1954
6418 	146 	F6-a 	61659 	November 1931	December 1954
6419 	139 	F6-a 	61660 	November 1931	August 1952
6420 	140 	F6-a 	61661 	November 1931	June 1954
6421 	141 	F6-a 	61662 	November 1931	October 1952
==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 service in 1935. The test used a regular service train from Chicago, Illinois to Milwaukee, Wisconsin, 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 840,000 pounds (380 t), #6402 completed the 85 miles (137 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 (110.63 km) between the Chicago suburb of Mayfair and Lake, Wisconsin was completed in 45 minutes and 53 seconds, an average of 89.89 mph (144.66 km/h). 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 (166.6 km/h) was reached. The fastest inter-station average speed was 95.6 mph (153.9 km/h) 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 (160 km/h) 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.
==References==
*Benn, Bryan, Which was the world's first genuine 100 mph steam locomotive?. Retrieved February 5, 2010.
Category:4-6-4 steam locomotives
Category:4-6-4 locomotives
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