LMS locomotive numbering and classification
Encyclopedia
A number of different numbering and classification schemes were used for the locomotives owned by the London, Midland and Scottish Railway
(LMS) and its constituent companies; this page explains the principal systems that were used.
The following abbreviations for the constituent companies are used on this page:
Caledonian Railway
(CR), Furness Railway
(FR), Glasgow and South Western Railway
(GSWR), Highland Railway
(HR), Lancashire and Yorkshire Railway
(LYR), London and North Western Railway
(LNWR), Maryport and Carlisle Railway
(MCR), Midland Railway
(MR), North London Railway
(NLR) and North Staffordshire Railway
(NSR)
Cleator and Workington Junction Railway
(C&WJR), Glasgow and Paisley Joint Railway
(G&PJR), Knott End Railway (KER), Stratford-Upon-Avon & Midland Junction Railway (S&MJR), and Wirral Railway
(WR)
Somerset and Dorset Joint Railway
(S&DJR) - absorbed October 1936
For information about individual classes and locomotives, see: Locomotives of the London, Midland and Scottish Railway
. In short, locomotives were numbered in a series commencing at 1. There were no gaps allowed in the series, so a new locomotive would either be numbered at the end of the series or would reuse the number of an older locomotive.
Older locomotives would then either be withdrawn or renumbered into the 'duplicate list' series used for locomotives no longer in capital stock but which were not yet completely life expired. These engines were numbered in various series over time: Initially they took an 'A' suffix to the original number, then from 1862 they were renumbered above 1100, from 1870 above 1800, and from 1886 in the 3xxx series.
The GJR and LNWR also named their passenger tender locomotives (indeed all locomotives were named until 1858), and often the same name and number combinations would be applied to new locomotives as they replaced older ones. The removal of names attached to freight engines after 1863 allowed them to be re-applied to the increasing stock of passenger engines, including those running on the former London and Birmingham Railway
are of the LNWR, where locomotives had not been named.
When the London, Tilbury and Southend Railway
(LTSR) was absorbed by the MR in 1912, its locomotives were renumbered into this scheme. It had only two tender engines, both 0-6-0 types, and these became 2898 and 2899. The rest were tank locomotives of varying wheel arrangements, which required the adoption of new number ranges at the end of the tank engine series. In all, the number ranges used by the MR were as follows:
Note: While the majority of ex-MR locomotives were left unrenumbered by the LMS at Grouping in 1923, the ex-LTSR locomotives were subject to several renumberings to clear space for new stock, which changed the number ranges set out above.
These advantages more than overcame the disadvantage of the effort involved in renumbering almost every locomotive and giving them a number that usually bore no relation to its pre-Grouping identity, except for the Midland Railway
locomotives that had been renumbered along similar lines in 1907 and mostly retained their numbers.
The system comprised four groups of numbers into which locomotives from a set of railways were numbered:
Within each group, locomotives were numbered in blocks which ran (low to high numbers) as set out below. Within each block, the least powerful locomotives took the lowest numbers.
When the Somerset and Dorset Joint Railway
locomotives were absorbed in 1930, they were mostly allocated numbers in the Midland Railway series (appropriate, since the SDJR had been jointly owned by the Midland Railway and many MR designs had been used on the SDJR), though some took numbers in the former LNWR series.
The introduction of this scheme involved renumbering both new and old locomotives to put them in the appropriate sequences. During the remainder of the 1930s, numbers were cleared for new locomotives by simply adding 20000 to the numbers of old locomotives.
Diesel shunters, which started to appear from the early 1930s onwards, were numbered in the same series as steam locomotives. Originally a series commencing at 7400 was planned, but it was soon evident that this would not provide sufficient space and it was replaced by a series commencing at 7050. The prototype mainline diesel locomotives
, the first of which was introduced at the end of 1947 just prior to Nationalisation were given the 'significant numbers' 10000 and 10001.
introduced a system of locomotive classification based on the power output represented by a locomotive's tractive effort
at 50mph (passenger locomotives) or 25mph (goods locomotives). This is the continuous tractive effort and is much lower than the starting tractive effort which is the figure usually quoted in technical publications.
This system was adopted by the LMS and also, from 1948 the nationalised British Rail
ways. The classification was made up of a number (representing the power output - 0 being low power and 9 high power) and a letter (representing the type of work the locomotive was intended for), e.g. 4F. Over the years there were some modifications to the system, but the basics remained the same.
The principal downside with this method of classification was that it did not distinguish between particular classes of locomotive, so many very different types would have been classified '4F' for instance.
The tables below provide definitions for the numbers and letters used:
F : Freight (from 1928)
G : Goods (until 1928)
MT: Mixed Traffic (Freight & Passenger)
P : Passenger
XP: Enhanced Passenger (higher end of power range)
A single number without a suffix letter was originally used by the LMS on locomotives that were not of Midland Railway origin until 1928. Thereafter, it was used to indicate a mixed traffic locomotive. Where a mixed traffic locomotive fell into different power ranges, dual classification was used, e.g. 5P4F. In the 1950s the suffixes 'FA' and 'FB' were used to distinguish between freight locos at the lower and higher ends of the power range.
London, Midland and Scottish Railway
The London Midland and Scottish Railway was a British railway company. It was formed on 1 January 1923 under the Railways Act of 1921, which required the grouping of over 120 separate railway companies into just four...
(LMS) and its constituent companies; this page explains the principal systems that were used.
The following abbreviations for the constituent companies are used on this page:
- Principal Constituents
Caledonian Railway
Caledonian Railway
The Caledonian Railway was a major Scottish railway company. It was formed in the early 19th century and it was absorbed almost a century later into the London, Midland and Scottish Railway, in the 1923 railway grouping, by means of the Railways Act 1921...
(CR), Furness Railway
Furness Railway
The Furness Railway was a railway company operating in the Furness area of Lancashire in North West England.-History:The company was established on May 23, 1844 when the Furness Railway Act was passed by Parliament...
(FR), Glasgow and South Western Railway
Glasgow and South Western Railway
The Glasgow and South Western Railway , one of the pre-grouping railway companies, served a triangular area of south-west Scotland, between Glasgow, Stranraer and Carlisle...
(GSWR), Highland Railway
Highland Railway
The Highland Railway was one of the smaller British railways before the Railways Act 1921; it operated north of Perth railway station in Scotland and served the farthest north of Britain...
(HR), Lancashire and Yorkshire Railway
Lancashire and Yorkshire Railway
The Lancashire and Yorkshire Railway was a major British railway company before the 1923 Grouping. It was incorporated in 1847 from an amalgamation of several existing railways...
(LYR), London and North Western Railway
London and North Western Railway
The London and North Western Railway was a British railway company between 1846 and 1922. It was created by the merger of three companies – the Grand Junction Railway, the London and Birmingham Railway and the Manchester and Birmingham Railway...
(LNWR), Maryport and Carlisle Railway
Maryport and Carlisle Railway
The Maryport & Carlisle Railway was a small but highly profitable railway formed in 1836 to connect the town of Maryport to the county town of Carlisle and to allow the output of collieries inland of Maryport to be more cheaply transported to Maryport for oward movement by sea. Its headquarters...
(MCR), Midland Railway
Midland Railway
The Midland Railway was a railway company in the United Kingdom from 1844 to 1922, when it became part of the London, Midland and Scottish Railway....
(MR), North London Railway
North London Railway
The North London Railway was a railway company that opened lines connecting the north of London to the East and West India Docks. The main east to west route is now part the North London Line. Other lines operated by the company fell into disuse, but were later revived as part of the Docklands...
(NLR) and North Staffordshire Railway
North Staffordshire Railway
The North Staffordshire Railway was a British railway company formed in 1845 to promote a number of lines in the Staffordshire Potteries and surrounding areas in Staffordshire, Cheshire, Derbyshire and Shropshire....
(NSR)
- Minor Companies
Cleator and Workington Junction Railway
Cleator and Workington Junction Railway
The Cleator & Workington Junction Railway was located in West Cumberland in Northern England, serving the towns of Cleator Moor and Workington and intermediate villages...
(C&WJR), Glasgow and Paisley Joint Railway
Glasgow and Paisley Joint Railway
The Glasgow and Paisley Joint Railway company was formed in 1837 to provide a railway link between Glasgow and Paisley, Scotland. It was promoted jointly by the Glasgow, Paisley and Greenock Railway and the Glasgow, Paisley, Kilmarnock and Ayr Railway....
(G&PJR), Knott End Railway (KER), Stratford-Upon-Avon & Midland Junction Railway (S&MJR), and Wirral Railway
Wirral Railway
The Wirral Railway was incorporated in 1863 as the Hoylake Railway , with powers to build lines from Birkenhead to New Brighton, and to Parkgate on the western side of the Wirral Peninsula; the latter line was not built. Between 1872 and 1882 the HR was renamed twice, and extensions of the line...
(WR)
- Later Additions
Somerset and Dorset Joint Railway
Somerset and Dorset Joint Railway
The Somerset & Dorset Joint Railway – almost always referred to as "the S&D" – was an English railway line connecting Bath in north east Somerset and Bournemouth now in south east Dorset but then in Hampshire...
(S&DJR) - absorbed October 1936
For information about individual classes and locomotives, see: Locomotives of the London, Midland and Scottish Railway
Locomotives of the London, Midland and Scottish Railway
The London, Midland and Scottish Railway had the largest stock of steam locomotives of any of the 'Big Four' Grouping, ie pre-Nationalisation railway companies in thec UK. Despite early troubles arising from factions within the new company, the LMS went on to build some very successful designs;...
London and North Western Railway
The LNWR inherited its numbering system from one of its constituents, the Grand Junction RailwayGrand Junction Railway
The Grand Junction Railway was an early railway company in the United Kingdom, which existed between 1833 and 1846 when it was merged into the London and North Western Railway...
. In short, locomotives were numbered in a series commencing at 1. There were no gaps allowed in the series, so a new locomotive would either be numbered at the end of the series or would reuse the number of an older locomotive.
Older locomotives would then either be withdrawn or renumbered into the 'duplicate list' series used for locomotives no longer in capital stock but which were not yet completely life expired. These engines were numbered in various series over time: Initially they took an 'A' suffix to the original number, then from 1862 they were renumbered above 1100, from 1870 above 1800, and from 1886 in the 3xxx series.
The GJR and LNWR also named their passenger tender locomotives (indeed all locomotives were named until 1858), and often the same name and number combinations would be applied to new locomotives as they replaced older ones. The removal of names attached to freight engines after 1863 allowed them to be re-applied to the increasing stock of passenger engines, including those running on the former London and Birmingham Railway
London and Birmingham Railway
The London and Birmingham Railway was an early railway company in the United Kingdom from 1833 to 1846, when it became part of the London and North Western Railway ....
are of the LNWR, where locomotives had not been named.
Midland Railway
The MR undertook a wholesale renumbering of its locomotive stock in 1907 based on usage, wheel arrangement, power classification (see classification section below), and age, with locomotives of the same class numbered together. The least powerful and oldest classes took the lowest numbers and locomotives were renumbered in order of age.When the London, Tilbury and Southend Railway
London, Tilbury and Southend Railway
The London, Tilbury and Southend Railway is an English railway line linking Fenchurch Street railway station in the City of London with northeast London and the entire length of the northern Thames Gateway area of southern Essex. It is currently known as the Essex Thameside Route by Network Rail...
(LTSR) was absorbed by the MR in 1912, its locomotives were renumbered into this scheme. It had only two tender engines, both 0-6-0 types, and these became 2898 and 2899. The rest were tank locomotives of varying wheel arrangements, which required the adoption of new number ranges at the end of the tank engine series. In all, the number ranges used by the MR were as follows:
| Number Range | Wheel Arrangement Whyte notation The Whyte notation for classifying steam locomotives by wheel arrangement was devised by Frederick Methvan Whyte and came into use in the early twentieth century encouraged by an editorial in American Engineer and Railroad Journal... | Power Classification |
|---|---|---|
| 1-1197 | Passenger tender engines | |
| 1-299 | 2-4-0 2-4-0 Under the Whyte notation for the classification of steam locomotives, 2-4-0 represents the wheel arrangement of two leading wheels on one axle, four powered and coupled driving wheels on two axles, and no trailing wheels.... |
1 |
| 300-599 | 4-4-0 4-4-0 Under the Whyte notation for the classification of steam locomotives, 4-4-0 represents the wheel arrangement of four leading wheels on two axles , four powered and coupled driving wheels on two axles, and no trailing wheels... |
1 and 2 |
| 600-699 | 4-2-2 4-2-2 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.... |
1 and 2 |
| 700-779 | 4-4-0 4-4-0 Under the Whyte notation for the classification of steam locomotives, 4-4-0 represents the wheel arrangement of four leading wheels on two axles , four powered and coupled driving wheels on two axles, and no trailing wheels... |
3 |
| 990-1197 | 4-4-0 4-4-0 Under the Whyte notation for the classification of steam locomotives, 4-4-0 represents the wheel arrangement of four leading wheels on two axles , four powered and coupled driving wheels on two axles, and no trailing wheels... |
4 |
| 1198-2199 | Tank engines | |
| 1198-1199 | 4-4-0 4-4-0 Under the Whyte notation for the classification of steam locomotives, 4-4-0 represents the wheel arrangement of four leading wheels on two axles , four powered and coupled driving wheels on two axles, and no trailing wheels... (Passenger) |
Not classified |
| 1200-1499 | 0-4-4 0-4-4 Under the Whyte notation for the classification of steam locomotives, 0-4-4 represents the wheel arrangement of no leading wheels, four powered and coupled driving wheels on two axles, and four trailing wheels on two axles... (Passenger) |
1 |
| 1500-1599 | 0-4-0 0-4-0 Under the Whyte notation for the classification of steam locomotives, 0-4-0 represents one of the simplest possible types, that with two axles and four coupled wheels, all of which are driven... (Freight) |
0 |
| 1600-1999 | 0-6-0 0-6-0 Under the Whyte notation for the classification of steam locomotives, 0-6-0 represents the wheel arrangement of no leading wheels, six powered and coupled driving wheels on three axles, and no trailing wheels... (Freight) |
1 and 3 |
| 2000-2099 | 0-6-4 0-6-4 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.... (Passenger) |
3 |
| 2100-2109 | 4-6-4 4-6-4 Under the Whyte notation for the classification of steam locomotives, 4-6-4 represents the wheel arrangement of four leading wheels on two axles , six powered and coupled driving wheels on three axles, and four trailing wheels on two axles .Other equivalent classifications are:UIC classification:... (Passenger) |
Ex-LTSR |
| 2110-2179 | 4-4-2 4-4-2 (locomotive) Under the Whyte notation for the classification of steam locomotives, 4-4-2 represents the wheel arrangement of four leading wheels on two axles , four powered and coupled driving wheels on two axles, and two trailing wheels on one axle... (Passenger) |
Ex-LTSR |
| 2180-2199 | 0-6-2 0-6-2 Under the Whyte notation for the classification of steam locomotives, 0-6-2 represents the wheel arrangement of no leading wheels, six powered and coupled driving wheels on three axles, and two trailing wheels on one axle... (Freight) |
Ex-LTSR |
| 2200 onwards | Freight tender engines | |
| 2200-2239 | 2-6-0 2-6-0 Under the Whyte notation for the classification of steam locomotives, 2-6-0 represents the wheel arrangement of two leading wheels on one axle, usually in a leading truck, six powered and coupled driving wheels on three axles, and no trailing wheels. This arrangement is commonly called a Mogul... |
2 |
| 2290 | 0-10-0 0-10-0 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... |
Not classified |
| 2300-2899 | 0-6-0 0-6-0 Under the Whyte notation for the classification of steam locomotives, 0-6-0 represents the wheel arrangement of no leading wheels, six powered and coupled driving wheels on three axles, and no trailing wheels... (Double framed) |
1 and 2 |
| 2900 onwards | 0-6-0 0-6-0 Under the Whyte notation for the classification of steam locomotives, 0-6-0 represents the wheel arrangement of no leading wheels, six powered and coupled driving wheels on three axles, and no trailing wheels... (Single framed) |
1 to 4 |
Note: While the majority of ex-MR locomotives were left unrenumbered by the LMS at Grouping in 1923, the ex-LTSR locomotives were subject to several renumberings to clear space for new stock, which changed the number ranges set out above.
Post-Grouping Numbering
Shortly after the LMS was formed in 1923, it developed a new numbering scheme for all the locomotives that it had inherited. The scheme dealt with two key problems faced by the new company:- There were many locomotives with the same number, as each of the constituent companies had used a series starting at number 1
- Many of the constituent companies had numbered their locomotives in a somewhat random way, and the renumbering allowed for all locomotives in the same class to be given consecutive numbers and similar classes to be numbered in blocks
These advantages more than overcame the disadvantage of the effort involved in renumbering almost every locomotive and giving them a number that usually bore no relation to its pre-Grouping identity, except for the Midland Railway
Midland Railway
The Midland Railway was a railway company in the United Kingdom from 1844 to 1922, when it became part of the London, Midland and Scottish Railway....
locomotives that had been renumbered along similar lines in 1907 and mostly retained their numbers.
The system comprised four groups of numbers into which locomotives from a set of railways were numbered:
| Number Range | Original Owning Company |
|---|---|
| 1-4999 | Midland Railway Midland Railway The Midland Railway was a railway company in the United Kingdom from 1844 to 1922, when it became part of the London, Midland and Scottish Railway.... (including the London, Tilbury and Southend Railway London, Tilbury and Southend Railway The London, Tilbury and Southend Railway is an English railway line linking Fenchurch Street railway station in the City of London with northeast London and the entire length of the northern Thames Gateway area of southern Essex. It is currently known as the Essex Thameside Route by Network Rail... , absorbed in 1912), North Staffordshire Railway North Staffordshire Railway The North Staffordshire Railway was a British railway company formed in 1845 to promote a number of lines in the Staffordshire Potteries and surrounding areas in Staffordshire, Cheshire, Derbyshire and Shropshire.... and Stratford-Upon-Avon & Midland Junction Railway |
| 5000-9999 | London and North Western Railway London and North Western Railway The London and North Western Railway was a British railway company between 1846 and 1922. It was created by the merger of three companies – the Grand Junction Railway, the London and Birmingham Railway and the Manchester and Birmingham Railway... (including the North London Railway North London Railway The North London Railway was a railway company that opened lines connecting the north of London to the East and West India Docks. The main east to west route is now part the North London Line. Other lines operated by the company fell into disuse, but were later revived as part of the Docklands... ) and Wirral Railway Wirral Railway The Wirral Railway was incorporated in 1863 as the Hoylake Railway , with powers to build lines from Birkenhead to New Brighton, and to Parkgate on the western side of the Wirral Peninsula; the latter line was not built. Between 1872 and 1882 the HR was renamed twice, and extensions of the line... |
| 10000-12999 | Lancashire & Yorkshire Railway, Furness Railway Furness Railway The Furness Railway was a railway company operating in the Furness area of Lancashire in North West England.-History:The company was established on May 23, 1844 when the Furness Railway Act was passed by Parliament... , Maryport and Carlisle Railway Maryport and Carlisle Railway The Maryport & Carlisle Railway was a small but highly profitable railway formed in 1836 to connect the town of Maryport to the county town of Carlisle and to allow the output of collieries inland of Maryport to be more cheaply transported to Maryport for oward movement by sea. Its headquarters... , Cleator and Workington Junction Railway Cleator and Workington Junction Railway The Cleator & Workington Junction Railway was located in West Cumberland in Northern England, serving the towns of Cleator Moor and Workington and intermediate villages... and Knott End Railway |
| 14000-17999 | Caledonian Railway Caledonian Railway The Caledonian Railway was a major Scottish railway company. It was formed in the early 19th century and it was absorbed almost a century later into the London, Midland and Scottish Railway, in the 1923 railway grouping, by means of the Railways Act 1921... , Glasgow and South Western Railway Glasgow and South Western Railway The Glasgow and South Western Railway , one of the pre-grouping railway companies, served a triangular area of south-west Scotland, between Glasgow, Stranraer and Carlisle... , Highland Railway Highland Railway The Highland Railway was one of the smaller British railways before the Railways Act 1921; it operated north of Perth railway station in Scotland and served the farthest north of Britain... and Glasgow and Paisley Joint Railway Glasgow and Paisley Joint Railway The Glasgow and Paisley Joint Railway company was formed in 1837 to provide a railway link between Glasgow and Paisley, Scotland. It was promoted jointly by the Glasgow, Paisley and Greenock Railway and the Glasgow, Paisley, Kilmarnock and Ayr Railway.... |
Within each group, locomotives were numbered in blocks which ran (low to high numbers) as set out below. Within each block, the least powerful locomotives took the lowest numbers.
| Block Description | MR etc Numbers | LNWR etc Numbers | LYR etc Numbers | Scottish Numbers |
|---|---|---|---|---|
| Passenger tender locomotives | 1-1199 | 5000-6399 | 10000-10599 | 14xxx |
| Passenger tank locomotives | 1200-1499 / 2000-2219 | 6400-6999 | 10600-11199 | 15xxx |
| Freight tank locomotives | 1500-1999 / 2220-2289 | 7xxx | 11200-11999 | 16xxx |
| Freight tender locomotives | 2290-4999 | 8xxx-9xxx | 12xxx | 17xxx |
When the Somerset and Dorset Joint Railway
Somerset and Dorset Joint Railway
The Somerset & Dorset Joint Railway – almost always referred to as "the S&D" – was an English railway line connecting Bath in north east Somerset and Bournemouth now in south east Dorset but then in Hampshire...
locomotives were absorbed in 1930, they were mostly allocated numbers in the Midland Railway series (appropriate, since the SDJR had been jointly owned by the Midland Railway and many MR designs had been used on the SDJR), though some took numbers in the former LNWR series.
New Locomotives
New-build LMS locomotives were not allocated any particular numbers, but were fitted into the most appropriate division. The unallocated 13xxx series of numbers were also used for new build LMS types.1932 Renumbering
In 1932, as older locomotives had been withdrawn and new standard LMS designs were becoming more common, it was decided that modifications should be made to the numbering system. In short, all LMS-built locomotives were to have numbers in the 1-9999 series, with pre-Grouping locomotives being renumbered out of that series as required to accommodate them.The introduction of this scheme involved renumbering both new and old locomotives to put them in the appropriate sequences. During the remainder of the 1930s, numbers were cleared for new locomotives by simply adding 20000 to the numbers of old locomotives.
Diesel shunters, which started to appear from the early 1930s onwards, were numbered in the same series as steam locomotives. Originally a series commencing at 7400 was planned, but it was soon evident that this would not provide sufficient space and it was replaced by a series commencing at 7050. The prototype mainline diesel locomotives
British Rail Class D16/1
British Railways Class D16/1 or 10000 and 10001 were the first mainline diesel locomotives in Great Britain. They were built by the London, Midland and Scottish Railway at its Derby Works, using the EE16SVT 1600 hp diesel engine with electric transmission, in association with English Electric and...
, the first of which was introduced at the end of 1947 just prior to Nationalisation were given the 'significant numbers' 10000 and 10001.
Application by British Railways
New engines built by British Railways to ex-LMS designs after Nationalisation in 1948 continued to use this numbering system, albeit with 40000 added to the numbers to avoid number conflicts with other absorbed engines (see BR locomotive and multiple unit numbering and classification). There were some minor amendments made by BR, however:- Former LMS diesel locomotives were numbered in the 10xxx series (mainline locomotives) and 12xxx series (shunters).
- Locomotives numbered above 20000 by the LMS were renumbered into the 58xxx series.
LMS System
The Midland RailwayMidland Railway
The Midland Railway was a railway company in the United Kingdom from 1844 to 1922, when it became part of the London, Midland and Scottish Railway....
introduced a system of locomotive classification based on the power output represented by a locomotive's tractive effort
Tractive effort
As used in mechanical engineering, the term tractive force is the pulling or pushing force exerted by a vehicle on another vehicle or object. The term tractive effort is synonymous with tractive force, and is often used in railway engineering to describe the pulling or pushing capability of a...
at 50mph (passenger locomotives) or 25mph (goods locomotives). This is the continuous tractive effort and is much lower than the starting tractive effort which is the figure usually quoted in technical publications.
This system was adopted by the LMS and also, from 1948 the nationalised British Rail
British Rail
British Railways , which from 1965 traded as British Rail, was the operator of most of the rail transport in Great Britain between 1948 and 1997. It was formed from the nationalisation of the "Big Four" British railway companies and lasted until the gradual privatisation of British Rail, in stages...
ways. The classification was made up of a number (representing the power output - 0 being low power and 9 high power) and a letter (representing the type of work the locomotive was intended for), e.g. 4F. Over the years there were some modifications to the system, but the basics remained the same.
The principal downside with this method of classification was that it did not distinguish between particular classes of locomotive, so many very different types would have been classified '4F' for instance.
The tables below provide definitions for the numbers and letters used:
| Power Class | Minimum & Maximum Tractive Effort (lbf) | |
|---|---|---|
| Passenger Locos at 50mph | Freight Locos at 25mph | |
| 0 | Under 3360 (used from 1928) | Under 6385 (used 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 and over | 18145 and over (used from 1937) |
| 9 | Not allocated | Used by British Railways from 1954 |
F : Freight (from 1928)
G : Goods (until 1928)
MT: Mixed Traffic (Freight & Passenger)
P : Passenger
XP: Enhanced Passenger (higher end of power range)
A single number without a suffix letter was originally used by the LMS on locomotives that were not of Midland Railway origin until 1928. Thereafter, it was used to indicate a mixed traffic locomotive. Where a mixed traffic locomotive fell into different power ranges, dual classification was used, e.g. 5P4F. In the 1950s the suffixes 'FA' and 'FB' were used to distinguish between freight locos at the lower and higher ends of the power range.