Steam Locomotives: The Art of Reversing Under Their Own Power
Steam locomotives may not be the most modern form of transport, but they have a unique capability that often gets overlooked: the ability to reverse under their own power. This marvel of engineering was achieved through various complex mechanisms, most commonly the Johnson bar and other reversing gears.
Understanding Reversing in Steam Locomotives
While steam locomotives could indeed reverse, this process required a specific setup. The Johnson bar, for instance, was a common mechanism that engineers used to change the direction of the locomotive. This device adjusted the position of the valve gear, altering the flow of steam to the cylinders, thereby enabling the locomotive to move in reverse.
Reversing a steam locomotive was not a simple task, much like the forward motion. Safety and control were paramount. For longer journeys, particularly on mainline routes, train operators often needed to turn the locomotive around using a turntable or a wye. A turntable would rotate the locomotive to face the correct direction, while a wye allowed the train to make a U-turn, facing the opposite way.
Practical Examples of Reversing Steam Locomotives
My personal experience with reversing steam locomotives comes from volunteering at the Keighley and Worth Valley Railway in West Yorkshire, UK. This railway is a living testament to the ingenuity of steam locomotives, where reversing them is a regular occurrence.
Due to the layout of the trains, steam locomotives can only travel forward or backward. From the front to the back, the train consists of a boiler for pressurized water, a firebox, the driving cabin, and a tender carrying coal or wood. As such, reversing the direction of the train is essential for certain operational needs.
In my experience at the Keighley and Worth Valley Railway, we lack traditional turntables. Instead, we use a series of route end track loops. When a steam train reaches the end of the line, engineers uncouple the passenger carriages and move the steam locomotive to the other end, ensuring that the locomotive always faces the direction of travel toward Oxenhope.
During busier operations, there may be a diesel locomotive at one end of the train, paired with a steam locomotive at the other. This fixed formation allows the train to shuttle back and forth throughout the day, utilizing both the diesel and steam locomotives efficiently. The drivers of both locomotives are in constant contact, ensuring the appropriate motive power during each trip.
A Contemporary Example
One recent instance involves a steam locomotive approaching Oxenhope on the Keighley and Worth Valley Railway. Trains on this route are often seen with a diesel locomotive at the front, providing the initial acceleration. As the train reaches the end of its journey, the steam locomotive switches to the rear, reversing its direction of travel, now pulled by the diesel at the front. This reversal is managed seamlessly through coordination between the train's safety and operational teams.
Pictures like the one taken in November 2023 by Nicholas Stone, the author of this answer, capture the essence of this unique transport method. These images not only document the beauty of steam locomotive travel but also highlight the intricate and effective mechanisms that made reversing possible.
From the intricacies of the Johnson bar to the practical considerations of reversing in steam locomotives, this capability remains a testament to the engineering prowess of the railways of the past. The ability to reverse under their own power, albeit complex, is a fascinating and often overlooked aspect of steam locomotive operation.