SR Z Class
Encyclopedia
The SR Z class was an 0-8-0T 3-cylinder tank engine designed by Richard Maunsell
and intended for heavy shunting on the Southern Railway, the first eight entering into service in 1929. It was a successful design and would have been built in greater numbers, but an order for a further ten was cancelled in 1930 due to the reduction in freight traffic as a result of the Great Depression
.
tank locomotives to work in its marshalling yards
around London and on freight transfers between them. Robert Urie
's G16 class
4-8-0
performed this task well, and further examples were on order in 1922, but Richard Maunsell considered the firebox to be too large and the superheater
an unnecessary expense on such locomotives. He therefore cancelled the order in favour of a new design.
Due to the requirement for heavy shunting, the design was provided with an 0-8-0 wheel arrangement to increase traction
, whilst enabling the locomotives to negotiate tight curves prevalent in goods yards. Another requirement was for the locomotive to be able to maintain power after long periods of standing idle, as freight marshalling was an intermittent duty. A 1500 gallon water capacity was also required to reduce the need for regular watering.
but, as a result of the unexpected need to redesign and rebuild the SECR K class
locomotives at Ashford, Maunsell decided to construct the Z class at Brighton
. One result of this change was that the boiler used was of an existing Brighton design, that of the D.E. Marsh C3 class
. The resultant design was a three-cylinder locomotive that incorporated Walschaerts outside valve gear, driving the third axle and a custom-built inside gear driving the second. The first of the class emerged from Brighton in March 1929 followed by the remainder over the next six months.
Steam and vacuum brakes, as well as steam heating were provided. This was to enable the locomotive to undertake the shunting of passenger stock should such a role be called for. A second batch of ten locomotives was planned to be constructed at Eastleigh
, but the economic climate in 1931 meant that the order was scrapped. By the time trade recovered in the mid 1930s, Maunsell had begun experimenting in the use of diesel-electric
locomotives
for these duties, and no further examples were built.
, Norwood Junction
, Exmouth Junction
and Eastleigh
, and proved to be very popular with the locomotive crews until they were replaced by diesel shunters of the class 12
in the early 1950s. They were less successful at Nine Elms
yard as the buffer beams overhung the ends of the locomotives by 11 ft in total, which could be a disadvantage when negotiating tight curves in a confined space during shunting.
In December 1942 three of the class were loaned to the War Department, and saw service in Scotland where their abilities to move heavy freight were needed to move troop trains and war materials over winding routes. These were considered a rarity amongst locomotive crews, and due to the customised inside valve gear, the regulators worked in a different fashion to the norm, therefore causing problems amongst those unfamiliar with the design. They returned to the Southern Railway in May 1943.
As more diesel-electric shunters were delivered during the 1950s the class was gradually transferred to less demanding work at Brighton
and Tonbridge
freight yards. Towards the end of their working lives, the entire class was moved to the Western section of the BR(S)(BR Southern Region), where their traction was put to good use in banking trains up the steep bank between Exeter St. David's
and Exeter Central
stations. However, with the reorganisation of the BR regions in 1962, the Western section of the BR(S) came under the control of the BR(W) (BR Western Region). As the Z Class was not of a standard design under BR (W) control, they were withdrawn throughout 1962, and banking duties were taken over by ex-GWR Pannier Tanks.
in Sussex. The locomotive was withdrawn from service in November 1962 and stored in working order at Exmouth Junction locomotive shed until the Spring of 1963. It was then moved to Fratton MPD where it was stored for the remainder of 1963 and most of 1964. In the event the preservation attempt failed, and the locomotive was on the scrap line at Eastleigh Works
, with coupling rods removed and tied to one side, by October 1964. It was at Bristol Barrow Road MPD for a short period early in 1965 while on its way to South Wales for scrapping. It was cut up at Cashmore
s of Newport
in May 1965.
Richard Maunsell
Richard Edward Lloyd Maunsell held the post of Chief Mechanical Engineer of the South Eastern and Chatham Railway from 1913 until the 1923 Grouping and then the post of CME of the Southern Railway in England until 1937....
and intended for heavy shunting on the Southern Railway, the first eight entering into service in 1929. It was a successful design and would have been built in greater numbers, but an order for a further ten was cancelled in 1930 due to the reduction in freight traffic as a result of the Great Depression
Great Depression
The Great Depression was a severe worldwide economic depression in the decade preceding World War II. The timing of the Great Depression varied across nations, but in most countries it started in about 1929 and lasted until the late 1930s or early 1940s...
.
Background
The newly amalgamated Southern Railway needed a group of powerful shuntingSwitcher
A switcher or shunter is a small railroad locomotive intended not for moving trains over long distances but rather for assembling trains ready for a road locomotive to take over, disassembling a train that has been...
tank locomotives to work in its marshalling yards
Classification yard
A classification yard or marshalling yard is a railroad yard found at some freight train stations, used to separate railroad cars on to one of several tracks. First the cars are taken to a track, sometimes called a lead or a drill...
around London and on freight transfers between them. Robert Urie
Robert Urie
Robert Wallace Urie was a Scottish locomotive engineer who was the last chief mechanical engineer of the London and South Western Railway....
's G16 class
LSWR G16 class
The LSWR G16 class is a steam tank locomotive class of 4-8-0T wheel arrangement. It was designed by Robert Urie and introduced in 1921 specifically for heavy shunting over humps at Feltham marshalling yard, on the London and South Western Railway...
4-8-0
4-8-0
Under the Whyte notation for the classification of steam locomotives, 4-8-0 represents the wheel arrangement of four leading wheels on two axles , eight powered and coupled driving wheels on four axles, and no trailing wheels. The type was nicknamed the Mastodon or Twelve-wheeler in North America....
performed this task well, and further examples were on order in 1922, but Richard Maunsell considered the firebox to be too large and the superheater
Superheater
A superheater is a device used to convert saturated steam or wet steam into dry steam used for power generation or processes. There are three types of superheaters namely: radiant, convection, and separately fired...
an unnecessary expense on such locomotives. He therefore cancelled the order in favour of a new design.
Due to the requirement for heavy shunting, the design was provided with an 0-8-0 wheel arrangement to increase traction
Traction (engineering)
Traction refers to the maximum frictional force that can be produced between surfaces without slipping.The units of traction are those of force, or if expressed as a coefficient of traction a ratio.-Traction:...
, whilst enabling the locomotives to negotiate tight curves prevalent in goods yards. Another requirement was for the locomotive to be able to maintain power after long periods of standing idle, as freight marshalling was an intermittent duty. A 1500 gallon water capacity was also required to reduce the need for regular watering.
Construction history
The new class was largely designed at Ashford railway worksAshford railway works
Ashford railway works was in the town of Ashford in the county of Kent in England.-South Eastern Railway:Ashford locomotive works was built by the South Eastern Railway on a new site in 1847, replacing an earlier locomotive repair facility at New Cross in London...
but, as a result of the unexpected need to redesign and rebuild the SECR K class
SECR K class
The SECR K class was a type of 2-6-4 tank locomotive designed in 1914 by Richard Maunsell for express passenger duties on the South Eastern and Chatham Railway . The Southern Railway K1 class was a three-cylinder variant of the K class, designed in 1925 to suit a narrower loading...
locomotives at Ashford, Maunsell decided to construct the Z class at Brighton
Brighton railway works
Brighton railway works was one of the earliest railway-owned locomotive repair works, founded in 1840 by the London and Brighton Railway in Brighton, England, and thus pre-dating the more famous railway works at Crewe, Doncaster and Swindon...
. One result of this change was that the boiler used was of an existing Brighton design, that of the D.E. Marsh C3 class
LB&SCR C3 class
The London, Brighton and South Coast Railway C3 class was a class of 0-6-0 steam locomotives, intended for heavy freight trains. Ten were built by Brighton railway works in 1906 to the design of Douglas Earle Marsh.-History:...
. The resultant design was a three-cylinder locomotive that incorporated Walschaerts outside valve gear, driving the third axle and a custom-built inside gear driving the second. The first of the class emerged from Brighton in March 1929 followed by the remainder over the next six months.
Steam and vacuum brakes, as well as steam heating were provided. This was to enable the locomotive to undertake the shunting of passenger stock should such a role be called for. A second batch of ten locomotives was planned to be constructed at Eastleigh
Eastleigh Works
Eastleigh Works is a locomotive, carriage and wagon building and repair facility in the town of Eastleigh in the county of Hampshire in England.-History under the LSWR:...
, but the economic climate in 1931 meant that the order was scrapped. By the time trade recovered in the mid 1930s, Maunsell had begun experimenting in the use of diesel-electric
Diesel-electric
Diesel-electric transmission or diesel-electric powertrain is used by a number of vehicle and ship types for providing locomotion.A diesel-electric transmission system includes a diesel engine connected to an electrical generator, creating electricity that powers electric traction motors...
locomotives
British Rail Class D3/12
British Rail class D3/12 was a class of three experimental diesel-electric shunting locomotives designed by Richard Maunsell of the Southern Railway in 1937...
for these duties, and no further examples were built.
Operational details
Throughout their working lives, the Z class locomotives remained in their role as heavy shunters in the larger marshalling yards at Hither GreenHither Green railway station
Hither Green is a railway station located in Hither Green in the London Borough of Lewisham, in southeast London, United Kingdom. Hither Green is a busy commuter station with services to several London termini and destinations to the southeast Hither Green is a railway station located in Hither...
, Norwood Junction
Norwood Junction railway station
Norwood Junction railway station is in South Norwood in the London Borough of Croydon in south London, in Travelcard Zone 4.The station is managed by London Overground and trains operated by Southern and London Overground .-History:...
, Exmouth Junction
Exmouth Junction
Exmouth Junction is the railway junction where the Exmouth branch line diverges from the London Waterloo to Exeter main line in Exeter, Devon, England. It was for many years the location for one of the largest engine sheds in the former London and South Western Railway...
and Eastleigh
Eastleigh railway station
Eastleigh railway station serves the town of Eastleigh in the county of Hampshire in England. It is located on the South Western Main Line and is the junction station for two other routes, the Eastleigh-Fareham Line and the Eastleigh-Romsey Line...
, and proved to be very popular with the locomotive crews until they were replaced by diesel shunters of the class 12
British Rail Class 12
The British Rail Class 12 is a diesel locomotive built primarily for shunting duties around London.-History:This was the second batch of Southern Railway shunters based on the English Electric 6KT 350 hp diesel engine. The first experimental batch were designed by Richard Maunsell of the SR in...
in the early 1950s. They were less successful at Nine Elms
Nine Elms
Nine Elms is a suburb of London, situated in the far north-eastern corner of the London Borough of Wandsworth between Battersea and Vauxhall.It is primarily an industrial area, dominated by Battersea Power Station, Battersea Dogs and Cats Home, railway lines, a major Royal Mail sorting office and...
yard as the buffer beams overhung the ends of the locomotives by 11 ft in total, which could be a disadvantage when negotiating tight curves in a confined space during shunting.
In December 1942 three of the class were loaned to the War Department, and saw service in Scotland where their abilities to move heavy freight were needed to move troop trains and war materials over winding routes. These were considered a rarity amongst locomotive crews, and due to the customised inside valve gear, the regulators worked in a different fashion to the norm, therefore causing problems amongst those unfamiliar with the design. They returned to the Southern Railway in May 1943.
As more diesel-electric shunters were delivered during the 1950s the class was gradually transferred to less demanding work at Brighton
Brighton railway station
Brighton railway station is the principal railway station in the city of Brighton and Hove, on the south coast of England. The station master is Mark Epsom...
and Tonbridge
Tonbridge railway station
Tonbridge railway station is a station serving the town of Tonbridge in Kent, England. It is a junction between two important commuter routes; the South Eastern Main Line serving Ashford, Ramsgate and Dover and the Hastings Main Line serving Tunbridge Wells and Hastings, as well as a branch to...
freight yards. Towards the end of their working lives, the entire class was moved to the Western section of the BR(S)(BR Southern Region), where their traction was put to good use in banking trains up the steep bank between Exeter St. David's
Exeter St Davids railway station
Exeter St Davids station is the most important of seven National Rail stations in the city of Exeter in southwest England. Today the station is owned by Network Rail and operated by First Great Western.-History:...
and Exeter Central
Exeter Central railway station
Exeter Central railway station is the most centrally located of the railway stations in Exeter, Devon, England. It is smaller than St Davids which is on the west side of the city but it is served by trains on the London Waterloo to Exeter main line, and is also by local services to , and . From...
stations. However, with the reorganisation of the BR regions in 1962, the Western section of the BR(S) came under the control of the BR(W) (BR Western Region). As the Z Class was not of a standard design under BR (W) control, they were withdrawn throughout 1962, and banking duties were taken over by ex-GWR Pannier Tanks.
Southern
Livery was black, with yellow numbering and 'Southern' on the tank sides. As the class were built at Brighton the locomotives should logically have been allocated numbers in the ‘B’ (Brighton) series but they rather entered traffic as A950-A957 reflecting their Ashford origins. However, by the time of the 1931 renumbering scheme when Ashford locomotives had 1000 added to their numbers, the numbers 1950-1957 had already been allocated. The class were therefore numbered in the western section sequence 950-957.Post-1948 (nationalisation)
Livery remained black in the guise of BR Freight Black, and the locomotives were provided with the BR crest on the tanks, whilst the numbering was located on the sides of the coal bunker. The Z class were given the numbers 30950–7 under the BR standard numbering system.Preservation
A private attempt was made in the 1960s to preserve a Z class, BR no 30952 with the intention to locate it on the Bluebell RailwayBluebell Railway
The Bluebell Railway is a heritage line running for nine miles along the border between East and West Sussex, England. Steam trains are operated between and , with an intermediate station at .The railway is managed and run largely by volunteers...
in Sussex. The locomotive was withdrawn from service in November 1962 and stored in working order at Exmouth Junction locomotive shed until the Spring of 1963. It was then moved to Fratton MPD where it was stored for the remainder of 1963 and most of 1964. In the event the preservation attempt failed, and the locomotive was on the scrap line at Eastleigh Works
Eastleigh Works
Eastleigh Works is a locomotive, carriage and wagon building and repair facility in the town of Eastleigh in the county of Hampshire in England.-History under the LSWR:...
, with coupling rods removed and tied to one side, by October 1964. It was at Bristol Barrow Road MPD for a short period early in 1965 while on its way to South Wales for scrapping. It was cut up at Cashmore
John Cashmore Ltd
John Cashmore Ltd was a company based at Newport, Monmouthshire, Wales...
s of Newport
Newport
Newport is a city and unitary authority area in Wales. Standing on the banks of the River Usk, it is located about east of Cardiff and is the largest urban area within the historic county boundaries of Monmouthshire and the preserved county of Gwent...
in May 1965.
Locomotive Summary
| SR No. | BR No. | Date Built | Date Withdrawn |
|---|---|---|---|
| 950 | 30950 | ||
| 951 | 30951 | ||
| 952 | 30952 | ||
| 953 | 30953 | ||
| 954 | 30954 | ||
| 955 | 30955 | ||
| 956 | 30956 | ||
| 957 | 30957 | ||