Milwaukee Road class F6

Milwaukee Road class F6 locomotive #6409.
Photo by Otto Perry at Chicago, Illinois on September 23, 1930.

Type and origin
Power type	Steam
Builder	Baldwin Locomotive Works
Serial number	61135–61148
Build date	January–March 1930

Specifications
Configuration	4-6-4
UIC class	2′C2′ h2
Gauge	4 ft 8 ¹⁄₂ in (1,435 mm) standard gauge
Leading dia	36 in (914 mm)
Driver diameter	79 in (2,007 mm)
Trailing dia	43 in (1,092 mm)
Loco weight	375,850 lb (170,480 kilograms; 170.48 metric tons)
Loco & tender weight	532,000 lb (241,000 kilograms; 241 metric tons)
Fuel type	Coal
Fuel capacity	40,000 lb (18,000 kilograms; 18 metric tons)
Water cap	15,000 US gal (57,000 l; 12,000 imp gal)
Firebox: • Firegrate area	80 sq ft (7.4 m²)
Boiler pressure	225 lbf/in² (1.55 MPa)
Feedwater heater	Coffin flush in smokebox
Cylinders	Two
Cylinder size	26 in × 28 in (660 mm × 711 mm)
Valve gear	Baker valve gear

Performance figures
Tractive effort	45,820 lbf (203.8 kN)

Career
Operators	Milwaukee Road
Class	F6
Number in class	14
Numbers	6400–6413; renumbered 125–138 in 1938
Delivered	1929
Retired	1952–1954
Disposition	All scrapped

Milwaukee Road class F6-a

Milwaukee Road F6-a locomotive #6417. Photo by Otto Perry at Chicago, Illinois on September 25, 1935.

Type and origin
Only items that differ from class F6 above are shown
Power type	Steam
Builder	Baldwin Locomotive Works
Serial number	61655–61662
Build date	October–November 1931

Specifications
Wheelbase	Loco: 40 ft 9 in (12.42 m)
Height	15 ft 6 in (4.72 m)
Loco weight	380,220 lb (172,460 kilograms; 172.46 metric tons)
Feedwater heater	Wilson Water Conditioner

Career
Operators	Milwaukee Road
Class	F6-a
Number in class	8
Numbers	6414–6421; renumbered 142–146, 139–141 in 1938

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. They would have been the first 4-6-4 tender locomotives 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 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 practise 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.

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^[1]
Original No.	1938 No.	Class	Baldwin serial No.	Built	Retired
6400	125	F6	61135	000000001930-01-01-0000January 1930	000000001954-06-01-0000June 1954
6401	126	F6	61136	000000001930-01-01-0000January 1930	000000001954-12-01-0000December 1954
6402	127	F6	61137	000000001930-01-01-0000January 1930	000000001954-02-01-0000February 1954
6403	128	F6	61138	000000001930-01-01-0000January 1930	000000001954-02-01-0000February 1954
6404	129	F6	61139	000000001930-01-01-0000January 1930	000000001953-12-01-0000December 1953
6405	130	F6	61140	000000001930-01-01-0000January 1930	000000001952-12-01-0000December 1952
6406	131	F6	61141	000000001930-01-01-0000January 1930	000000001952-09-01-0000September 1952
6407	132	F6	61142	000000001930-01-01-0000January 1930	000000001952-10-01-0000October 1952
6408	133	F6	61143	000000001930-01-01-0000January 1930	000000001952-10-01-0000October 1952
6409	134	F6	61144	000000001930-01-01-0000January 1930	000000001954-07-01-0000July 1954
6410	135	F6	61145	000000001930-01-01-0000January 1930	000000001954-09-01-0000September 1954
6411	136	F6	61146	000000001930-02-01-0000February 1930	000000001954-11-01-0000November 1954
6412	137	F6	61147	000000001930-02-01-0000February 1930	000000001954-12-01-0000December 1954
6413	138	F6	61148	000000001930-03-01-0000March 1930	000000001954-12-01-0000December 1954
6414	142	F6-a	61655	000000001931-10-01-0000October 1931	000000001954-12-01-0000December 1954
6415	143	F6-a	61656	000000001931-10-01-0000October 1931	000000001954-12-01-0000December 1954
6416	144	F6-a	61657	000000001931-10-01-0000October 1931	000000001954-12-01-0000December 1954
6417	145	F6-a	61658	000000001931-10-01-0000October 1931	000000001954-12-01-0000December 1954
6418	146	F6-a	61659	000000001931-11-01-0000November 1931	000000001954-12-01-0000December 1954
6419	139	F6-a	61660	000000001931-11-01-0000November 1931	000000001952-08-01-0000August 1952
6420	140	F6-a	61661	000000001931-11-01-0000November 1931	000000001954-06-01-0000June 1954
6421	141	F6-a	61662	000000001931-11-01-0000November 1931	000000001952-10-01-0000October 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”.^[2]

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

↑ Edson 1977, p. 49.
↑ Reed, p. 28.

Benn, Bryan, Which was the world's first genuine 100 mph steam locomotive?. Retrieved February 5, 2010.
Edson, William D. (Spring 1977). "Milwaukee Road All Time Steam, Diesel and Electric Roster". Railroad History (Railway and Locomotive Historical Society Inc.) (136): 49.
Reed, Brian (1972). Loco Profile 26 – The Hiawathas. Windsor, Berkshire, UK: Profile Publications Ltd.
Westcott, Linn H. (1960). Model Railroader Cyclopedia - Volume 1: Steam Locomotives. Milwaukee, Wisconsin: Kalmbach Books. pp. 203–207. ISBN 0-89024-001-9.

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