UK Steam Trains
steam train ajax steam locomotive at the isle of wight railway foremarke hall steam locomotive at the gwr cheltenham Home Maps The Big 4 History of Steam The Loco's Reference
s of Loco

Types of Locomotive

Atlantic           4-4-2 Mogul             2-6-0           Pacific            4-6-2 Prairie            2-6-2  
Side Tank
Saddle Tank
In 1900 Frederick Whyte developed a way of describing the many types of wheel arrangements of Steam locomotives, This became known as the Whyte Notation. Using Whyte’s system you first count the number of leading wheels, then the driving wheels and then the trailing wheels. Using Whyte’s  notation a locomotive with two leading axles (4 wheels) in front, 3 driving axles (6 wheels) and one trailing axle (2 wheels) would be classified as a 4-6-2 a Pacific Class.  
Mikado
Consolidation   2-8-0
2-8-2
Mountain
4-8-2
Decapod
2-10-10
Power Classifications
The Midland Railway used a power classification based on the power output of a locomotives pulling or pushing force (Tractive Effort) at 50mph for passenger locomotives and 25mph for goods. This force is the tractive effort that can be indefinitely maintained and this is called the Continuous Tractive Effort. After the railway nationalisation in 1948, British Railways also adopted it. This system used a numbering system from 0-9 with 0 being the lowest power. Using this system however it was possible to have different classes of locomotive with the same power classification.  Power Class    Minimum & Maximum Tractive Effort lbf                                        Passenger locos 50mph     Freight Locos 25mph    
Classes
0                  under 3360 from 1928        under 6385 from 1928 1                  3360-4479                          6385-8064 2                  4480-5599                          8065-9744 3                  5600-6719                          9745-11424 4                  6720-7839                          11425-13104 5                  7840-8959                          13105-14784 6                  8960-10079                        14785-16464 7                 10080-11199                       16465-18144 8                 11200 & over                       18145 & over 9                 Not allocated                       used by British Railways  from 1954

Types of Locomotive

Tank Engines or  a tank locomotive carries it’s water in on board water tanks instead of carrying it in a tender pulled behind it. There were several different types of water tank configurations depending on there style and position. The type with two tanks, one each side of the boiler which originated in about 1840 were the most common. These were popular for shunting and shorter distance routes as hey could not carry large amounts needed for longer journeys. Locos that carry there water on board are called Tank engines.
side tank steam locomotive at the isle of wight railway a saddle tank steam locomotive
Saddle Tank locomotives had there water tank wrapped around the top of the boiler.
a tender steam locomotive
Tender Locomotives
Tender Locomotives as there name suggests pulled a Tender behind them which contained the fuel and water. Steam locomotives used a larger amount of water compared with fuel so needed to carry large quantities for long journeys.
Pannier Locomotives
a pannier tank steam locomotive
Pannier Locomotives had two water tanks one on each side of the boiler but not resting on the runing plate. This type of locomotive had a much lower centre of gravity compared to the saddle tank arrangement.
These wheel classifications would be followed by suffix to denote the type of loco. The Side Tank Engine shown below would be a 0-6-0T Side Tank=T        Saddle Tank=ST         Pannier=PT         Well Tank=WT  
Understanding Steam locomotive classes can seem quite confusing, especially for someone new to the subject. Steam Locos come in many shapes, sizes and power levels. Different railways favoured different classes of Locomotive depending on the work needing to be done. Many had the same class of loco but built and redesigned by themselves to suit there own requirements. Batches of locos would be given names, Jubilee Class, King Class or you might hear one referred to as a Gresley A1 or A3 after one of there famous designers. All the designers from all of the railways tried to make their designs the most efficient, fastest and most reliable.  
F = Freight   G = Goods    Mt = Mixed Traffic P = passenger    XP = Enhanced Passenger
Locos would be described as an 8F or a 7p etc depending on there power class and type of usage.
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