SCOA-P pattern wheels are a type of steam locomotive wheel. Rather than having traditional solid spokes, the SCOA-P spoke is hollow, with a 'U' shaped cross section. They are considerably lighter than a conventional spoked wheel or Boxpok wheel of the same size and strength.
SCOA-P wheels were developed in the late 1940s by the Steel Company of Australia Ltd (the P in the acronym standing for F. C. Paynter, who patented the design) [1] in response to Victorian Railways experiencing fatigue problems with conventional spoked wheels. Stronger Boxpok type 'B' wheels had been installed on a number of VR locomotive classes in the late 1940s, but they had the disadvantage of being relatively heavy and also restricted maintenance access to axleboxes, underslung springs, and in some cases boiler washout plugs. Boxpok wheels were proposed for the forthcoming Victorian Railways R class 4-6-4, which had a relatively heavy 19.5-long-ton (19.8 t) axle load, but it had been discovered that the use of a Boxpok wheel would make coupling rod pin removal difficult. The SCOA-P wheel was developed to allow the strength of the Boxpok design but also provide the maintenance access of a conventional spoked wheel.
The SCOA-P wheel centre of a 73-inch R class driving wheel weighed only 1,829 pounds (830 kg), 322 lb (146 kg) lighter than a Boxpok design of the same diameter and equivalent strength. [2] Using a 100-long-ton (100 t) vertical press, load testing was conducted of the strength and elasticity of the SCOA-P wheel centre against a 2,021 lb (917 kg) conventional spoked driving wheel centre of an A2 class locomotive that had the same diameter, but was engineered for a lower 17.5-long-ton (17.8 t) axle load). The tests revealed that the SCOA-P wheel was still elastic at 23.4 long tons (23.8 t), with a permanent set occurring at about 30 long tons (30 t), whereas the conventional spoked wheel experienced permanent set at 20 long tons (20 t). [2]
SCOA-P wheels were used on Victorian Railways' R class 4-6-4 and J class 2-8-0 locomotives, introduced in 1951 and 1954 respectively. They were also used on the Queensland Railways BB18¼ class 4-6-2 and Tasmanian Government Railways M class 4-6-2 and H class 4-8-2. [3]
Because the Vulcan Foundry, which built the VR J class, built SCOA-P wheeled locomotives for export until ceasing steam locomotive production in 1956, this wheel type was also seen in many of Vulcan's other export markets.
SCOA-P wheel centres were found on locomotives for the Gold Coast Railway in Africa (WM and YL classes), East African Railways (30 [4] and 31 [5] classes), Iran Railways' 2-10-2 Decapod, [6] and a class of Indian Government Railways' 2-8-4T tank locomotives, [7] among others.
A Fairlie is a type of articulated steam locomotive that has the driving wheels on bogies. The locomotive may be double-ended or single ended. Fairlies are most associated with the Ffestiniog Railway in Wales.
Under the Whyte notation for the classification of steam locomotives, 4-6-2 represents the wheel arrangement of four leading wheels on two axles, six powered and coupled driving wheels on three axles and two trailing wheels on one axle. The 4-6-2 locomotive became almost globally known as a Pacific type.
Under the Whyte notation for the classification of locomotives, 4-6-4 represents the wheel arrangement of four leading wheels, six powered and coupled driving wheels and four trailing wheels. In France where the type was first used, it is known as the Baltic while it became known as the Hudson in most of North America.
Under the Whyte notation for the classification of steam locomotives, 4-8-4 represents the wheel arrangement of four leading wheels on two axles, eight powered and coupled driving wheels on four axles and four trailing wheels on two axles. The type was first used by the Northern Pacific Railway, and initially named the Northern Pacific, but railfans and railroad employees have shortened the name when referring to the type, and now is most commonly known as a Northern.
Under the Whyte notation for the classification of steam locomotives, 2-10-0 represents the wheel arrangement of two leading wheels on one axle, ten powered and coupled driving wheels on five axles, and no trailing wheels. This arrangement was often named Decapod, especially in the United States, although this name was sometimes applied to locomotives of 0-10-0 "Ten-Coupled" arrangement, particularly in the United Kingdom. Notable German locomotives of this type include the war locomotives of Class 52.
Vulcan Iron Works was the name of several iron foundries in both England and the United States during the Industrial Revolution and, in one case, lasting until the mid-20th century. Vulcan, the Roman god of fire and smithery, was a popular namesake for these foundries.
Under the Whyte notation for the classification of steam locomotives, 2-8-2 represents the wheel arrangement of two leading wheels on one axle, usually in a leading truck, eight powered and coupled driving wheels on four axles and two trailing wheels on one axle, usually in a trailing truck. This configuration of steam locomotive is most often referred to as a Mikado, frequently shortened to Mike.
Under the Whyte notation for the classification of steam locomotives, 0-10-0 represents the wheel arrangement of no leading wheels, ten powered and coupled driving wheels on five axles and no trailing wheels. In the United Kingdom, this type is known as a Decapod, a name which is applied to 2-10-0 types in the United States.
GT3, meaning Gas Turbine number 3, was a prototype mainline gas turbine locomotive built in 1961 by English Electric at their Vulcan Foundry in Newton-le-Willows to investigate the use of its gas turbines in rail traction applications. It was designed by English Electric engineer J. O. P. Hughes in a project that started in the early 1950s. Externally it resembled a steam tender locomotive, although, in the case of GT3, the tender carried kerosene fuel. The designer stated the use of a traditional chassis arrangement and mechanical transmission was to avoid complicating the prototype with relatively untried technologies with regard to bogie assemblies and electrical transmission.
Under the Whyte notation for the classification of steam locomotives, 0-6-4 represents the wheel arrangement of no leading wheels, six powered and coupled driving wheels on three axles, and four trailing wheels on two axles.
A Boxpok is a steam locomotive wheel that gains its strength through being made of a number of box sections rather than having traditional solid spokes. Being hollow, they allow better counterbalancing than conventional drivers, which is important for fast locomotives. The Boxpok wheel was patented by General Steel Castings Corporation of Granite City, Illinois.
The K class was a branch line steam locomotive that ran on Victorian Railways in Australia from 1922 to 1979. Although its design was entirely conventional and its specifications unremarkable, the K class was in practice a remarkably versatile and dependable locomotive. It went on to outlast every other class of steam locomotive in regular service on the VR, and no fewer than 21 examples of the 53 originally built have survived into preservation.
The Victorian Railways J class was a branch line steam locomotive operated by the Victorian Railways (VR) between 1954 and 1972. A development of the successful Victorian Railways K class 2-8-0, it was the last new class of steam locomotive introduced on the VR. Introduced almost concurrently with the diesel-electric locomotives that ultimately superseded them, these locomotives were only in service for a relatively short time.
The DD class (later reclassified into D1, D2 and D3 subclasses) was a passenger and mixed traffic steam locomotive that ran on Victorian Railways from 1902 to 1974. Originally introduced on mainline express passenger services, they were quickly superseded by the much larger A2 class and were relegated to secondary and branch line passenger and goods service, where they gave excellent service for the next fifty years. The DD design was adapted into a 4-6-2T tank locomotive for suburban passenger use, the DDE (later D4) class. They were the most numerous locomotive class on the VR, with a total of 261 DD and 58 locomotives built.
The 18 class was a class of 0-6-0T wheel arrangement steam locomotive built by Vulcan Foundry for the New South Wales Government Railways of Australia.
The Queensland Railways BB18¼ class locomotive was a class of 4-6-2 steam locomotives operated by the Queensland Railways.
The Victorian Railways V Class is a steam locomotive, used on the Victorian Railways in the period 1900-1930.
The South African Railways Class 5 4-6-2 of 1912 was a steam locomotive.
The South African Railways Class F 4-6-4T of 1904 was a steam locomotive from the pre-Union era in Transvaal Colony.
The Bulleid Firth Brown wheel (BFB) was a locomotive wheel developed for the Southern Railway in the late 1930s. It was a disc wheel, in contrast to the usual spoked wheels in general use on British railways. The wheel was designed by Oliver Bulleid and developed by the steel company Firth Brown of Sheffield.
