Patentee
The Patentee Class was a 2-2-2 locomotive type designed by Robert Stephenson & Co. and patented in 1833 as a development of the preceding Planet Class design, representing one of the most significant evolutionary steps in early steam locomotive engineering. While the Planet Class of 1830 had established the basic arrangement of inside cylinders driving a single central driving axle, the Patentee design added a trailing axle behind the firebox, transforming the 2-2-0 Planet into a 2-2-2 with improved stability at higher speeds and a better-distributed weight that reduced the stress on the driving axle bearings. This single change — the addition of a rear carrying axle — was foundational for British locomotive design and established the 2-2-2 single-driver express wheel arrangement that dominated British express practice for the next forty years.
The Patentee's significance lay not just in its mechanical improvement over the Planet but in its exportability: Robert Stephenson & Co. supplied Patentee-type locomotives to railways across Britain and continental Europe, and the type became the de facto standard express locomotive of the 1830s and 1840s. Railways as varied as the Liverpool and Manchester, the Grand Junction, the London and Birmingham, the North Midland, and the Belgian State Railways all operated Patentee-type locomotives, making it one of the most widely-built early locomotive types and a key vehicle for the spread of Stephenson's locomotive technology across the industrialising world.
The Patentee design influenced virtually every subsequent British express locomotive through to the 1890s: the 2-2-2 single-driver types of the Great Northern, LNWR, Midland, and GWR all descended directly from the Patentee's wheel arrangement and general configuration. No original Patentee survives in operable form, though several replicas and partial remains are held in various museums.
Design and development
The Planet design of 1830, though revolutionary, was limited by its short wheelbase: as boilers grew larger to deliver more steam, the engine became unstable at speed. Robert Stephenson's solution, patented in 1833 and giving the class its name, was to add a single pair of carrying wheels behind the firebox, producing a 2-2-2 layout with the firebox suspended between the driving and trailing axles. The longer wheelbase improved stability, allowed a larger boiler and firebox, and gave more room for water and coal.
The Patentee proved enormously influential: it was supplied to the London & Birmingham, the Grand Junction, the early GWR (as the broad-gauge Star class), and to railways in Belgium, the Netherlands, Germany, Russia, and Austria. Over 70 were built between 1834 and 1840.
Service and withdrawals
The Patentees were the standard British express engine of the 1830s, working passenger trains on every major main line as it opened. They were progressively replaced by larger 2-2-2s and Bury bar-frame engines from the 1840s onwards, but many lasted until the 1850s, and several of the Continental examples remained in service even longer. None of the originals were preserved, but the layout was the direct ancestor of every 19th-century British single-driver express engine.
Identification features
2-2-2 layout with a single pair of large driving wheels (typically 5 ft 6 in to 6 ft 0 in), inside cylinders at the smokebox end, and a long Stephenson sandwich frame extending the full length of the engine. The trailing carrying axle distinguishes the class from the earlier Planet.
Notable locomotives
- Patentee (1834, not preserved)
- Replica of broad-gauge Patentee variant (North Star) at STEAM Swindon
