Locomotion No. 1 (originally named Active) was an early steam locomotive built by the pioneering railway engineers George and Robert Stephenson's via their manufacturing firm, Robert Stephenson and Company. It became the first steam locomotive to carry passengers on a public rail line, the Stockton and Darlington Railway.
Locomotion was originally ordered by the Stockton and Darlington Railway Company on 16 September 1824; its design greatly benefitted from the experience that George Stephenson had acquired during the construction of the previous series of Killingworth locomotives. Weighing a total of 6.6 tonnes, extensive use of cast iron was made throughout the vehicle, although some elements, such as the engine frame, were composed of timber instead. Fitted with a total of four driving wheels, it is believed that Locomotion was the first locomotive to make use of coupling rods to link together its driving wheels for greater adhesion and less slippage when accelerating. However, the adoption of a centre-flue boiler proved to be a weakness, providing for a poor heating surface compared to subsequently-built locomotives.
On 27 September 1825, Locomotion hauled the first train on the Stockton and Darlington Railway, becoming the first locomotive to run on a public railway; after this occasion, it was routinely used by the railway. On 1 July 1828, it was heavily damaged as a result of a boiler explosion while at Aycliffe Lane station, resulting in the death of its driver, John Cree. While it was rebuilt, as a consequence of the rapid advances in the capability of locomotives, Locomotion became obsolete within the space of a decade. Rebuilt after the boiler explosion, it was used on the line up until 1841, after which Locomotion adapted to function as a stationary engine. During 1857, as a consequence of its historical importance, Locomotion was preserved and subsequently put on display. Between 1892 and 1975, it was on static display at one of the platforms at Darlington Top Bank railway station. It is presently at the Darlington Railway Centre and Museum, now known as Head of Steam. A working replica of Locomotion has also been built and is currently at Beamish Museum.
On 23 June 1823, the pioneering locomotive manufacturer Robert Stephenson and Company was established by the railway engineers George Stephenson and his son Robert Stephenson. During November of that year, only months following its commencement of operations, a key early order for the company was placed by the Stockton & Darlington Railway Company for a total of four stationary engines. On 16 September 1824, the railway company also ordered a pair of steam locomotives, each of which reportedly costing around £550.
This order was a historically important one as the first of these locomotives, which was originally given the name ‘’Active’’ and later renamed Locomotion, was not only the first steam locomotive to be constructed for the Stockton & Darlington Railway, it would also result in the operation of the first steam-powered passenger railway anywhere in the world. While this line was worked by steam, the steep inclines present along the route required the use of static engines to move trains, as the primitive locomotives of the day struggled to perform such ascents unaided.
The design of Locomotion combined all of the accumulated improvements that George Stephenson had pioneered in the development and construction of the previous Killingworth locomotives. The vehicle possessed a total weight of 6.6 tonnes; many elements, including the boiler, cylinders and wheels, were composed of cast iron, while the engine frame was composed of timber instead. There were a total of four driving wheels present, which had a diameter of 1.22 meters and were configured in a 0-4-0 arrangement.
Locomotion used high-pressure steam, which was generated within a centre-flue boiler and drove a pair of vertical cylinders, which were enclosed within and ran in-line with the boiler itself. This boiler was furnished with a steam-blast in the chimney. As a consequence of the single flue arrangement, it had a poor heating surface compared to later steam locomotives. It is believed that Locomotion possessed a maximum speed of 15 mph (24 km/h). A pair of yokes positioned above the cylinders transmitted the power downwards through pairs of connecting rods, making use of a loose eccentric valve gear; it has been claimed that Locomotion was the first locomotive to use coupling rods to link its driving wheels together, rather than achieving this through either chains or gears, an approach which considerably increased adhesion to the rails.