User:Colin Douglas Howell/Galleries/Planet and other similar 2-2-0s of the 1830s

During the early to mid 1830s, the 2-2-0 became the most popular configuration for British and European passenger locomotives.

The cylinder layout of Robert Stephenson's 0-2-2s had serious drawbacks. With the cylinders at the rear next to the firebox, and the driving wheels at the front, the driving wheels only supported a minority of the locomotive's weight, which limited the tractive force available. This was further aggravated by the fact that when the locomotive pulled a train, its front end could be lifted by the force on the drawbar, reducing traction even more. The solution was to move the driving wheels to the rear and the cylinders to the front. This layout was adopted by most later steam locomotives.

The other problem with the cylinder arrangement on the Stephenson 0-2-2s was that they had cylinders outside the frames together with a short wheelbase. This combination allowed the alternating piston thrusts to easily torque the locomotive left and right, producing a "boxing" serpentine motion. To counter this, Stephenson and many other British builders adopted cylinders placed inside the frames driving a crank axle. With inside cylinders, the lateral lever arm of the piston thrusts was shortened, reducing the left-right torques and the locomotive's tendency to "snake".

Another major reason for the adoption of inside cylinders was that it insulated the cylinders within the hot smokebox, reducing heat losses from radiation. This significantly improved the engine's efficiency.

This altered arrangement of rear driving wheels with inside cylinders was the defining feature of Stephenson's next major locomotive class, the Planet, and gave rise to the popular 2-2-0 type.

Stephenson's Planet-type 2-2-0 locomotives, 1830
In late 1830, just a short time after the opening of the Liverpool and Manchester Railway, Robert Stephenson introduced a new locomotive, Planet, with its driving wheels in the rear and inside cylinders in the front, integrated with the smokebox. Soon afterward this locomotive set a new record of one hour for the 50 km Liverpool-Manchester run. It was much more effective than the old 0-2-2s and became the basis for an entire class of Liverpool and Manchester locomotives, the Planet class. It was the first locomotive type to be built in significant numbers. Stephenson also built examples for other railways, and many other builders followed the design, sometimes with modifications. The Planet-type and other similar 2-2-0s became the dominant British and European passenger locomotives of the early to mid-1830s and remained popular for the rest of the decade, with many serving into the 1840s. Though later Stephenson locomotives had different wheel arrangements, they still followed the basic pattern set by Planet.

American railroads also ordered and built Planet-type locomotives, but their popularity in America was short-lived. The type was designed for British railways, which had been carefully engineered at great expense to avoid sharp curves and steep grades. American lines were usually built on the cheap, with twisty, undulating, hilly lines, and the British locomotives found such conditions very difficult to handle.

Planet has not survived, but a working replica was built in 1992 for Manchester's Museum of Science and Industry.

Richard Roberts' vertical-cylindered 2-2-0s, 1833-1834
One unusual variant of the 1830s 2-2-0 was the vertical-cylindered type developed by Richard Roberts and built by Sharp, Roberts & Co. At first glance it was similar to an ordinary Planet-type 2-2-0, but the cylinders were mounted vertically on either side of the boiler above the front wheels, and the piston rods drove the driving wheels via outside bell cranks and connecting rods. There was no crank-axle, and the motion was fully visible. The first of these locomotives was Experiment, built in 1833 for the Liverpool and Manchester. Starting in 1834, three others were built for the Dublin and Kingstown Railway, Ireland's first railway. The first of these, Hibernia, was the first locomotive to run in Ireland. The type was short-lived, largely due to the use of troublesome piston valves. (Almost all other 19th-century locomotives used slide valves.)

Bury bar-framed 2-2-0s, 1837
Edward Bury was one of the most important English locomotive designers of the 1830s, and his locomotives had a distinctive style of their own. Instead of the typical plate frames used on most British locomotives, Bury's used bar frames. Though bar frames did not catch on in Britain, many U.S. builders adopted them, and eventually they became the standard for 19th-century American locomotives.

Bury's machines also had a unique style of firebox, an upright cylinder with a hemispherical top and a semicircular fire grate. The idea was to strengthen the boiler by keeping all its pressure vessels circular in form, though in practice Bury boilers were expensive to build and not especially strong. Their greatest advantage was ample steam room. The constraints imposed by the Bury boiler's shape limited the grate size and engine power. As a result, Bury's engines remained somewhat small when locomotives were growing in size. Bury boilers were also adopted by U.S. builders early on, and were continued by them into the 1850s.

A whole series of Bury-type 2-2-0s and 0-4-0s were built from 1837 to 1841 for the newly opened London and Birmingham Railway to serve as its first locomotives. This new railway was the most important one in Britain, and Bury contracted to run its trains at a set price per passenger and per ton of goods per mile, using locomotives provided by the L&BR to his specification. They were built by seven different manufacturers, including Bury's own firm. This contract never worked in practice and in 1839 Bury was apppointed as locomotive manager on a fixed salary, plus a profits bonus. He believed strongly in using small, cheap locomotives, simply utilizing more of them when extra power was needed. Heavy passenger trains on the London and Birmingham frequently used two, three, or even four Bury 2-2-0s.