as depicted in the October 16, 1830 issue of ''
Mechanics' Magazine''.
Rocket The 0-2-2 or
Northumbrian wheel arrangement was first used for
Stephenson's Rocket, their entry for the
Rainhill Trials of 1829, a competition to choose a locomotive design for the new
Liverpool and Manchester Railway. Stephenson recognised that the rules of the competition favoured a fast, light locomotive of only moderate hauling power. Although
George Stephenson's
previous designs had been heavy four-coupled freight locomotives,
Rocket was almost entirely new. Stephenson was an advocate of the
adhesion railway, against the fashion of the time, and believed that the light loads for Rainhill would even allow just a single driving axle. This allowed the simplification of not requiring either a
chain drive between the axles or Stephenson's invention of the external
coupling rods. Achieving adequate traction required more of ''Rocket's
weight to be over the driving axle than the carrying axle. The heavy boiler was placed forwards, with the axle beneath it, giving a 0-2-2 layout rather than . The cylinders were set at a steep angle, as used the year before for Lancashire Witch'', rather than the typical vertical cylinders of this period. The cylinders were thus over the
firebox and both driver and fireman shared a footplate at the same, rear, end of the engine. Previously they had often been separated to their own ends of the engine.
Novelty Ericsson and
Braithwaite's entry for the Trials, their
Novelty, was an 0-2-2
well tank locomotive. Both the
driving wheels and
trailing wheels were the same size, and there may also have been the facility to fit a coupling chain drive to give better adhesion "when needed".
Novelty has also been described as a [ design, as there is no clear "front" or "rear" to this design.
Northumbrian Rocket was the only locomotive to complete the trials successfully and Stephenson became the supplier of locomotives to the L&MR. The 0-2-2 arrangement was subsequently used by
Robert Stephenson and Company on eight locomotives supplied to the
Liverpool and Manchester Railway after 1829:,
Meteor,
Comet,
Dart,
Arrow,
Phoenix,
North Star,
Northumbrian, and
Majestic. Like the rebuilt
Rocket, these had their cylinders set low in a near-horizontal position. The
Northumbrian type was superseded by the
Planet type. These reversed the layout, placing the cylinders inside, between the
frames, and below the
smokebox at the front. The inside cylinders were closer together, giving less of a
rocking couple and so were less prone to
yawing oscillation at speed. Placing the cylinders below the smokebox also permitted shorter steampipes and exhaust pipes to the
blastpipe, giving better efficiency.
Northumbrians were the last, and only, production locomotives with this wheel arrangement. After the
Planets, most passenger locomotives began to use a arrangement, with an additional front carrying axle to give better riding at speed. == Tank engines ==