Under the Whyte notation for the classification of steam locomotives, 4-2-2 represents the wheel arrangement of four leading wheels on two axles, two powered driving wheels on one axle, and two trailing wheels on one axle.
Other equivalent classifications are:
Like other steam locomotive types with single pairs of driving wheels, they were also known as singles.
The 4-2-2 configuration offered designers eight wheels to spread the weight of a larger locomotive, but prior to the bogies (invented in the 1830s) becoming popular, created a long rigid wheelbase with limited adhesion. As a result, the type was relatively rare until the 1870s. The first steam locomotive made by Borsig of Berlin in 1841, the Borsig No 1, was a 4-2-2, but the company quickly reverted to the more common 2-2-2 configuration.
The London and North Western Railway No. 3020 Cornwall was built as 4-2-2 at Crewe Works in 1847, but was extensively rebuilt, and converted to a 2-2-2 in 1858.
The one area where the type proved to be useful was on broad gauge locomotives, where sharp bends were less of an issue. Daniel Gooch built 29 examples of his Iron Duke express locomotive class for the Great Western Railway between 1847 and 1855. [1] They had an 8 ft (2.4 m) diameter driving wheel size. Twenty examples of a similar design were built for the Bristol and Exeter Railway after 1849, by Stothert & Slaughter in Bristol. [2] Because both sets of leading wheels are mounted independently in the frames in these classes, they are sometimes described as (2-2)-2-2 rather than 4-2-2. [3]
The first 4-2-2 to have a bogie was built by Archibald Sturrock of the Great Northern Railway (GNR) in 1853. This had 7 ft 0 in (2.134 m) flangeless driving wheels, and was only moderately successful, having a tendency to derail. [4] By the 1870s, improved design of bogies giving more flexibility enabled designers to create fast standard gauge express passenger locomotives of this type. On the GNR, Patrick Stirling built 53 examples with outside cylinders at Doncaster Works between 1870 and 1895, for use on the East Coast Main Line between London King's Cross and York. They ran at an average speed of more than 60 mph (97 km/h) during the race to the north, and were called eight-footers because of the driving wheel, that was more than 8 ft (2.4 m) in diameter. Stirling's successor Henry Ivatt built a further twelve singles between 1898 and 1901 before moving on to larger 4-4-2 designs.
The attraction of the 'single' (4-2-2 or otherwise) was that, thanks to the 'gearing' effect of the large single driving wheels, a locomotive could obtain high speeds while the operating speed of the engine's pistons and valve gear remained relatively low. This was important because of the relatively unsophisticated lubrication systems available at the time, with many of the parts of the engine's motion requiring to be 'oiled round' with the locomotive stationary before and after a run, or on longer trips by one of the crew taking to the running board to oil the required parts while on the move. Low piston speed also meant that the steam demand on the boiler would be relatively low, allowing a smaller, lighter boiler.
Before the development of the 'large boiler' designs in the 1890s, many boilers could not sustain the steam supply required of a small-wheeled locomotive operating at speed, thus requiring the large driving wheels of a single. At 70 mph (110 km/h), an 'eight-footer' single's driving wheels would be revolving at 245 revolutions per minute, opposed to the 327 revolutions of the driving wheels of a 'six-footer'. A locomotive with coupled wheels also suffered extra rolling resistance from the presence of coupling rods between the driving wheels which incurred a slight but measurable resistance arising from the small variances in the diameter of the driving wheels that were nominally of the same size. This meant that without the coupling rods, for a given locomotive speed the driving wheels would turn at very slightly different rate, but the coupling rods and the axles forced the driving wheels to turn at the same speed, with the added work being incurred as a binding force in the coupling rod bearings. Aside from this force, the coupling rod bearings themselves were a source of rolling resistance. Additionally, each driving axle of a locomotive had to be supported on large plain bearings, with required further lubrication, introducing a potential point of mechanical failure through overheating and a considerable source of friction. With only one driving axle, a 'single' had much less rolling resistance than a four-coupled engine, requiring less steam to achieve a given speed and also being more free-running when coasting downhill.
The 4-2-2 wheel arrangement had other specific advantages - the front bogie supported the weight of large cylinders and a long boiler which could exceed the load limits on a single front axle while also providing a superior stability and cornering at high speeds. Without restriction from a rear driving axle and wheels, a wide and deep firebox could be used, carried by the small single trailing axle, which provided good steam-making properties and a large ashpan making these locomotives suitable for running long distances at high speeds.
The Stirling 'eight-footers' were very successful, but were best suited to the predominantly straight and flat GNR main line in Cambridgeshire and the Vale of York. Other railways slowly replaced their original 'singles' with 4-4-0 locomotives that offered better traction at the cost of ultimate speed. However, in 1886 Francis Holt, manager at the Derby Works of the Midland Railway invented a practical form of steam sanding gear which allowed locomotive crews to quickly and effectively stop wheelspin. This led to the Midland reviving the 'single' in the form of the distinctive inside-cylinder "Spinners"; eighty-five were built to five designs by Samuel Waite Johnson between 1887 and 1900. [5] One 115 class, No. 673, survives at the National Railway Museum in York. Concurrent with Holt's invention was the so-called Race to the North, when groups of railway companies on the East Coast and West Coast routes between London and Edinburgh competed with each for the fastest journey times. For its portion of the West Coast route, the Caledonian Railway used its unique 4-2-2, No. 123. This had been built in 1885 as a showpiece for the 1886 world's fair in Edinburgh rather than to fulfil a traffic need for the railway, and so had used the now-unfashionable 4-2-2 'Single' layout. But when pressed into service during the Race to the North, No. 123's high speed performance and reliability made other locomotive engineers reconsider the advantages of the single-driver engine, especially when joined with the new steam-sander (No. 123 had a similar sanding system working by compressed air).
These factors lead to a resurgence of interest in the 'single' for fast express passenger work in the 1880s and 1890s. William Dean of the Great Western Railway built fifty examples of the standard gauge 3031 Achilles Class from 1893 to 1899. [6] No. 3065 Duke of Connaught contributed to the record-breaking run of the Ocean Mail express train from Plymouth to Paddington in 227 minutes on 9 May 1904, when it took over the train at Bristol from No 3440 City of Truro and completed the journey to Paddington in 99 minutes 46 seconds. By 1900, average train loads had grown beyond the capability of even a sander-fitted 'single' and their development was stopped. On the GNR, Stirling's famous 'eight-footers' required double heading with 4-4-0s before they were replaced by the 'Klondyke' 4-4-2 engines designed by Henry Ivatt, while on the Midland Railway Samuel Johnson developed a powerful compound 4-4-0 to replace his 'Spinners'.
Other notable UK examples of the 4-2-2 include the GER Class P43, which was an early oil-burning engine, developed by the pioneer of oil-boilers, James Holden. The last British 'single' to be designed was the Class 13 of the Great Central Railway, designed by Harry Pollitt in 1900 for work on the company's new main line to London. Ivatt Class A5 singles of the GNR, designed before the Great Central engines, continued to enter service during 1901, being the last of their type to take to the rails in Britain.
The T. D. Judah locomotive was built as a 4-2-4 by the Cooke Locomotive and Machine Works in 1863. It was purchased for use on the Central Pacific Railroad and was rebuilt as a 4-2-2 in 1872.
By 1900, typical loads on express trains had grown beyond the capabilities of 4-2-2 locomotives and the configuration was superseded by the 4-4-2.
In 1910, the British locomotive manufacturer Kerr, Stuart and Company produced four 4-2-2 locomotives, weighing 120 tons and with 7 ft driving wheels, for the Shanghai–Nanjing railway. [7] [8] These were the last recorded 'singles' built and almost certainly the largest.
A steam locomotive is a locomotive that provides the force to move itself and other vehicles by means of the expansion of steam. It is fuelled by burning combustible material to heat water in the locomotive's boiler to the point where it becomes gaseous and its volume increases 1,700 times. Functionally, it is a steam engine on wheels.
On a steam locomotive, a driving wheel is a powered wheel which is driven by the locomotive's pistons. On a conventional, non-articulated locomotive, the driving wheels are all coupled together with side rods ; normally one pair is directly driven by the main rod which is connected to the end of the piston rod; power is transmitted to the others through the side rods.
The UIC classification of locomotive axle arrangements, sometimes known as the German classification or German system, describes the wheel arrangement of locomotives, multiple units and trams. It is used in much of the world, notable exceptions being the United Kingdom, which uses a slightly simplified form of UIC, and in North America, where the AAR wheel arrangement system is used to describe diesel and electric locomotives. In North America, the Whyte notation is only used for steam locomotives.
Main components found on a typical steam locomotive include:
Under the Whyte notation for the classification of steam locomotives, 4-2-0 represents the wheel arrangement of four leading wheels on two axles, two powered driving wheels on one axle and no trailing wheels. This type of locomotive is often called a Jervis type, the name of the original designer.
A Crampton locomotive is a type of steam locomotive designed by Thomas Russell Crampton and built by various firms from 1846. The main British builders were Tulk and Ley and Robert Stephenson and Company.
Under the Whyte notation for the classification of steam locomotives by wheel arrangement, 4-4-2 represents a configuration of a four-wheeled leading bogie, four powered and coupled driving wheels, and two trailing wheels supporting part of the weight of the boiler and firebox. This allows a larger firebox and boiler than the 4-4-0 configuration.
Under the Whyte notation for the classification of steam locomotives, 4-2-4 represents the wheel arrangement of four leading wheels on two axles, two powered driving wheels on one axle, and four trailing wheels on two axles.
An 0-2-2, in the Whyte notation for the classification of steam locomotives by wheel arrangement, is one that has two coupled driving wheels followed by two trailing wheels, with no leading wheels. The configuration was briefly built by Robert Stephenson and Company for the Liverpool and Manchester Railway.
The Great Northern Railway (GNR) Small Boiler Class C1 is a class of steam locomotive, the first 4-4-2 or Atlantic type in Great Britain. They were designed by Henry Ivatt in 1897. In total 22 were built between 1898 and 1903 at Doncaster Works. The class were commonly known as 'Klondykes' [sic], after the 1897 Klondike gold rush. They could reach speeds of up to 90 mph. They were also known as Small Atlantics.
The Great Northern Railway (GNR) No. 1 class Stirling Single is a class of steam locomotive designed for express passenger work. Designed by Patrick Stirling, they are characterised by a single pair of large driving wheels which led to the nickname "eight-footer". Originally the locomotive was designed to haul up to 26 passenger carriages at an average speed of 47 miles per hour (76 km/h). They could reach speeds of up to 85 mph.
Patrick Stirling was a Scottish railway engineer, and Locomotive Superintendent of the Great Northern Railway of England. His father Robert Stirling was also an engineer. His brother James Stirling was also a locomotive engineer. His son Matthew Stirling was CME of the Hull and Barnsley Railway. Another son, Patrick Stirling played for Doncaster Rovers and was mayor of Doncaster.
B-B and Bo-Bo are the Association of American Railroads (AAR) and British classifications of wheel arrangement for railway locomotives with four axles in two individual bogies. They are equivalent to the B′B′ and Bo′Bo′ classifications in the UIC system. The arrangement of two, two-axled, bogies is a common wheel arrangement for modern electric and diesel locomotives.
The Dean Single, 3031 Class, or Achilles Class was a type of steam locomotive built by the British Great Western Railway between 1891 and 1899. They were designed by William Dean for passenger work. The first 30 members of the class were built as 2-2-2s of the 3001 Class.
The Great Northern Railway (GNR) Class C1 is a type of 4-4-2 steam locomotive. One, ex GNR 251, survives in preservation. Much like their small boiler cousins, they were capable of reaching speeds of up to 90 mph (145 km/h). They were also known as Large Atlantics.
London and North Western Railway (LNWR) 2-2-2 No. 3020 Cornwall is a preserved steam locomotive. She was built as a 4-2-2 at Crewe Works in 1847, but was extensively rebuilt and converted into her current form in 1858.
The leading wheel or leading axle or pilot wheel of a steam locomotive is an unpowered wheel or axle located in front of the driving wheels. The axle or axles of the leading wheels are normally located on a leading truck. Leading wheels are used to help the locomotive negotiate curves and to support the front portion of the boiler.
A steam motor is a form of steam engine used for light locomotives and light self-propelled motor cars used on railways. The origins of steam motor cars for railways go back to at least the 1850s, if not earlier, as experimental economizations for railways or railroads with marginal budgets. These first examples, at least in North America, appear to have been fitted with light reciprocating engines, and either direct or geared drives, or geared-endless chain drives. Most incorporated a passenger carrying coach attached to the engine and its boiler. Boiler types varied in these earlier examples, with vertical boilers dominant in the first decade and then with very small diameter horizontal boilers. Other examples of steam motor cars incorporated an express-baggage or luggage type car body, with coupling apparatus provided to allow the steam motor car to draw a light passenger coach.
Rigid-framed electric locomotives were some of the first generations of electric locomotive design. When these began the traction motors of these early locomotives, particularly with AC motors, were too large and heavy to be mounted directly to the axles and so were carried on the frame. One of the initial simplest wheel arrangements for a mainline electric locomotive, from around 1900, was the 1′C1′ arrangement, in UIC classification.
The GNR Classes D2 and D3 were two classes of 51 4-4-0 steam locomotives designed by Henry Ivatt for the Great Northern Railway (GNR). They were the first 4-4-0s to be introduced by the GNR, and Ivatt's first original design for the railway as well.