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In 1944, the PRR received a Baldwin-built straight steam turbine where the turbine was geared down and directly connected to the drivers. It looked much more like a regular steam locomotive. The most obvious visual clue that it was not a "normal" steam locomotives was that it had to cylinders and main rods. It still had side rods connecting the main drivers.

Class S2 number 6200 was built with a new wheel arrangement: 6-8-6. Initially, it was designed to be a 4-8-4. However, because of wartime restrictions on lightweight metals, the locomotive weight required the larger pilot and tender trucks. It had two steam turbines, one large one for forward movement and one small one for backup movements.

It too was unsuccessful. Once it got up to speed it could outpull anything on the rails at the time but most locomotives don't spend that much time rocketing across the plains at 100 mph. Below 40 miles per hour, it used an enormous ammount of steam and coal. It was used in passenger service between Crestline, OH and Chicago, IL before being placed in storage and later scrapped.

The PRR also had designs on the board for large Baldwin steam-turbine-electrics similar to the C&O units but they were canceled before metal was cut.

More :
One problem with conventional reciprocating steam locomotives is that when the horizontal motion of the pistons is converted into rotary motion of the drive wheels, the torque is not constant throughout the rotation of the wheels. Instead, if the torque per plotted on a graph, it would be represented as a sine-based wave, having high points and low points. The practical result of non-constant torque on drive wheels is a vehicle whose wheels may easily slip when starting.

Another problem with conventional reciprocating steam locomotives is that all of the side rods and valve gear become difficult to balance when the locomotive is traveling at high speeds.

In the 1920s and 1930s, the United States locomotive builders began looking at turbine power like that which is used in steamships and stationary power plants as an alternative to the more traditional reciprocating power. During the next few decades several steam-turbine designs were tested and used. However, none were really a success. Steam turbines make great nautical motors, where the hull of a ship provides a comparatively clean and cushioned enviroment. Railroad locomotives get dirty while they are running over the road, and freight locomotives also are involved in many low speed high impact collisions coupling up to trains. Passenger locomotives, with a fixed consit were safe from the violence of coupling onto a train, but their higher speeds made them even dirtier than a freight locomotive going thirty or forty miles an hour.

The photos