Between 1932 and 1936, the Baltimore & Ohio built four different and unique 4-6-4 „Hudsons” which were designated classes V-1 to V-4. What they had in common was the water tube firebox designed by master mechanic Colonel George H. Emerson. After the V-1 had been a rebuild of a P-1c Pacific with an extremely long firebox, the V-2 was built from the ground up in 1935 in the B&O's Mount Clare Shops.

It got the number 2 and was named “Lord Baltimore”. Inspired by the British GWR King class No. 6000 “King George V” that had visited the Fair of the Iron Horse, it was designed with all tubes and rods inside the boiler shell to create a clean look. The boiler itself was operated with an exceptionally high pressure of 350 psi. Large drivers with a diameter of 84 inches and cylinders with a small diameter assured high speeds with light trains.

After No. 2, the B&O built two additional 4-6-4 in its Mount Clare Shops in 1935. No. 2 was used to haul the new lightweight train “Royal Blue” between New York City and Washington, D.C. Later it hauled short express trains over the hilly line between Washington, D.C. and Cumberland, Maryland. It was scrapped in 1949, its sisters a year later.

H1b No. 2816 in September 2007 in Milwaukee

Brian Cazel

The 65 class H1a to H1e locomotives were built for use in front of express and freight trains. Starting with the H1c, they received partial streamlined fairing. After King George VI's train was pulled by an H1d on his visit to Canada in 1939, all streamlined Hudsons were officially allowed to call themselves “Royal Hudson”. The five H1s built in 1940 finally had oil firing. They were replaced by diesel locomotives by 1960 and some continued to run excursion trips for a longer period of time.

The class L-2 Hudsons of the Chesapeake & Ohio were 4-6-4 express locomotives introduced in 1942 to haul the fastest trains on level routes. They had to haul 15-car trains at 90 mph or 145 km/h. Trains on mountainous routes were already hauled by the “Greenbrier” 4-8-4 which had been introduced in 1935.

Their features included 78 inch (1,981 mm) drivers and a large 255 psi (17.6 bars) boiler with thermic syphons and an Elesco feed water heater. All axles of the locomotive and even the side rods had roller bearings. The Franklin type E booster was a special express variant that allowed operation up to 33 mph or 53 km/h.

The original class L-2 consisted of eight locomotives built in December 1941 and the following January. In 1948, five more of a revised design followed as L-2a. They had Franklin rotary cam poppet valves instead of piston valves and were the last steam express locomotives any US railroad purchased. After only a short career, they were scrapped in 1953.

In addition to the tank locomotives of the class 61, the need for more powerful express locomotives was also recognized in order to be able to transport regular, heavier express trains at higher speeds. A tender followed among various companies, the winner of which was a streamlined 4-6-4 locomotive from Borsig. In contrast to its competitors, some of which were also designed as steam turbine locomotives, the class 05 was created as a conventional three-cylinder steam locomotive, which was based as far as possible on the design of the standard locomotives. In 1935 road numbers 05 001 and 05 002 were built in the regular design, followed in 1937 by the different 05 003.

The locomotives had coupling wheels measuring 2,300 mm and a two-axle bogie at the front and rear. The streamlining completely covered the running gear, it had a straight lower edge and went down to a few centimeters above the rail heads. The five-axle 2'3 T37 tender was also paneled, but otherwise mostly compatible with the standard design. The tender's paneling was flush with the locomotive's paneling, removable, and closed off the cab at the rear.

Test drives showed an indicated power of around 2,360 hp, but significantly more was possible for a short time. The regular maximum speed was 150 km/h, and 175 km/h was approved to make up for delays. A typical train mass for these speeds was given as 250 tonnes.

Calculations had shown that at 140 km/h a performance increase of 385 hp at the towing hook had been achieved through the fairing. As with all large standard locomotives, the problem was the large length of the heating pipes, which here reached 7,000 mm and tended to lead to tension. In contrast to most other locomotives of this time, the coupling wheels were braked on both sides and, in addition, a speed-dependent control of the brake was achieved by means of a centrifugal governor. This allowed the usual train weight to come to a standstill at a distance of 1,200 meters from the distant signal within a defined time.

During the test drives and in the subsequent scheduled use of the first two engines, they often exceeded the requirements. The rule were trains consisting of five heavy express cars and together weighing almost 250 tonnes. In the process, speeds were kept above the permitted maximum speed over longer distances on several occasions. On May 11, 1935, road number 05 002 drove between Hamburg and Berlin with only four cars. Although no record run was planned, the speedometer needle reached its stop at 200 km/h and stayed there for a long time. Using the milestones and time measurements, an average of 200.4 km/h was calculated over 5 km and 201 km/h for a short time.

In addition to a calculated output of 3,400 hp, this meant a speed record for steam locomotives, which is still disputed today. The record is often attributed to the English “Mallard” with 201.2 km/h, but not only did this trip take place on a slight downward gradient, it also resulted in damage from an overheated bearing on the connecting rods and it is usually claimed that the trip was not adequately documented. Some American locomotives also allegedly reached over 220 km/h, but in these cases there is no reliable documentation.

The third locomotive followed in a very unusual configuration, since at these speeds there were advantages in moving the driver's cab forward. In order to avoid separating the fireman and driver, the boiler was installed backwards. Since the firebox was now on the opposite side of the tender, pulverized coal firing was installed. The coal dust was transported through a pipe that ran through the entire frame and also had bends due to the inner cylinder. Another difference was the installation of a combustion chamber to allow the gases, which were very hot after the rapid combustion, to cool down a little before hitting the heating tubes. The design of 05 003 did not work, as there was a lack of combustion air in many situations and there were frequent blockages due to slag deposits. Finally in 1944, the boiler was rotated to the conventional position and converted to fire regular coal while the cladding was removed.

In contrast to almost all locomotives available in small numbers, the German Federal Railroad did not decommission the three 05s because they could not do without these fast and more powerful engines. During the rebuild in 1950, the remnants of the paneling, which had already been damaged during the war, were also removed from 05 001 and 002. This did not result in any noticeable disadvantages because the network no longer allowed the highest speeds. However, the boiler pressure was reduced from 20 to 16 bars to reduce the wear.

In 1957 and 1958, the three units were replaced by class V 200 diesel locomotives. Road numbers 002 and 003 were then scrapped by 1960, with only the 001 remaining. The paneling of the latter was then largely restored and the locomotive was taken to the Nuremberg Transport Museum.

In the 1930s, the Nord was planning a new express locomotive that, due to its size, should achieve lower operating costs with longer trains and should also ideally be suitable for the speed range between 160 and 200 km/h.

In order to be able to determine the ideal cylinder arrangement, Marc de Caso developed the 232 R with a simple three-cylinder engine and the 232 S with a four-cylinder compound engine. Due to the founding of the SNCF, the program was postponed and the three 232 R were therefore only delivered in 1940.

The wheel arrangement chosen was 4-6-4 since it was possible to use a boiler of the same size as a 4-8-2 and at the same time take over large chassis parts from a 4-6-2 and replace the trailing axle with a bogie. A streamlined fairing was necessary in order to be able to reach the required speeds.

Locomotive Magazine, January 1948

The boiler was operated at a relatively high pressure of 20 bar. Otherwise, the locomotives had a Lemaître blast pipe, an ACFI feed water heater and modern injectors. The tender was basically designed for 38 m³ of water, but could only hold 36 m³ with the built-in stoker. On an incline of 0.4 percent, they could tow 685 tonnes at 113.5 km/h, which corresponded to an output at the drawbar of 2,615 hp. 

The tractive effort calculated from the cylinders is more of a theoretical value that could only hardly be achieved under real conditions. The practical quotient of adhesive weight and tractive effort for three-cylinder locomotives is usually given as 3.5, but it is 2.65 here. Thus, depending on the condition of the rails, there will have been a strong tendency to slip. If you take the value 3.5 as a basis, you get a realistic pulling force of 193 kN or 43,400 pounds. 

The three locomotives were tested on the Paris-Lille route in front of regular trains. Due to the war, their power could not be fully exploited and they were only approved for 140 km/h. Two locomotives were retired in 1958 and the third in 1961.

In addition to the 232 R with a simple three-cylinder engine, the Nord had the 232 S developed with a four-cylinder compound engine. It was therefore also used to test powerful express locomotives for the highest speed range. Due to the founding of the SNCF, the program was postponed and the four 232 S were therefore only delivered in 1941. They had streamlined bodywork that looked very similar to the 232 R. The similar 232 U 1, ordered at the same time, was not completed until 1949.

The Zara valves of the four cylinders were controlled by a rotating Dabeg camshaft control. Otherwise, the locomotives had a Lemaître blast pipe, an ACFI feed water heater and modern injectors. The boiler worked with a pressure of 20 bars. The tender was basically designed for 38 m³ of water, but could only hold 36 m³ with the built-in stoker. On a gradient of 0.5 percent, they could pull 595 tonnes at 113 km/h, which corresponded to an output of 3,400 hp. 

The four locomotives were tested on two different lines in front of regular trains. Due to the war, the performance of the locomotives could not be fully exploited and they were only approved for 140 km/h. Since the valve gear had problems, it had to be replaced in 1954 with another one with an oscillating camshaft. Their service life ended in 1961 and the SNCF did not order any more express locomotives with a 4-6-4 wheel arrangement, as locomotives with four coupled axles were now used for the heaviest trains.

In 1929, Gresley attempted to build a high-pressure locomotive using the Yarrow boiler from shipbuilding. This boiler consisted of three barrels arranged in a delta shape and was not divided into a firebox and a boiler barrel. It was faired with a streamlined mantle and operated at 450 psi. The chassis came from an A1 Pacific and was expanded to include an additional, independently movable trailing axle. A four-cylinder compound engine was used, which had relatively small cylinders due to the high pressure. Since the boiler did not meet the expectations placed upon it, the locomotive was rebuilt with a conventional boiler in 1936 and was given three cylinders of the same size.

The Nacional de Mexico received ten Hudsons from ALCO in Schenectady in 1937. With an adhesive weight of 170.000 pounds, they were among the lightest North American locomotives with this wheel arrangement. Thanks to their oil firing, they were able to stay in service well into the 1960s. Number 2708 survives today, retired in 1963 and on display in the Plaza de las Tres Centurias in Aguascalientes.

The first Hudsons of the Milwaukee Road were built by Baldwin between 1929 and 1931. While the first 14 locomotives were designated as class F6 and their running boards were broken above the air tank, the last eight were designated as F6a and had straight running boards. They were delivered with driving wheels with a diameter of 79 inches, which later increased to 80 inches due to thicker tires. The coffin feed water heater was apparently integrated into the smokebox for aesthetic reasons.

The boiler had a large firebox, which resulted in a load on the trailing bogie of around 53 tons. The express trains they hauled usually consisted of nine to ten cars, but often eleven to 14 cars and were occasionally even longer. With these trains, the 918-mile round trip between Minneapolis and Harlowton could be completed ten times in 30 days without any servicing stops. A lighter train covered a flat section of 65.6 miles at an average of 92.3 mph. 

To replace the Pacifics on the Twin Cities Hiawatha, the Milwaukee Road introduced a new type of Hudson or Baltic locomotives in 1938. The six locomotives were built by ALCO-Schenectady, received the numbers 100 to 105 and were designated class F-7. Their streamlined casing was designed by Otto Kuhler.

They were similar to the Chicago & North Western's class E-4, but had differences in the boiler and the cylinder dimensions. Their boiler was similar in size with some 4-8-4s and might have generated a power of around 5,000 hp. With their 84-inch drivers, they regularly travelled longer distances with more than 100 mph. Speeds they actually reached amounted to 120 mph, with up to 125 mph over short distances being claimed.

No. 100

collection Taylor Rush

On the Hiawatha, they reduced the travel time for the 412 miles between Chicago and the Twin Cities of Minneapolis and St. Paul to six and a half hours. There they had to do average speeds of more than 80 mph for an hour to keep up with the schedule. When the Twin Cities Hiawatha was dieselized, they were used on other Hiawatha trains. After a short career, they were scrapped between 1949 and 1951.