O4  63570 – 63920  2-8-0  GCR & ROD  Robinson  



O4 1.jpg

o4 2.jpg

Power Classification 7F
Introduced 1911– 1920
Designer Robinson
Company GCR and ROD
Weight – Loco 73t 4cwt
               Tender 47t 6cwt
Driving Wheels 4ft 8ins
Boiler Pressure 180psi superheated
Cylinders Outside – 21in x 26in
Tractive Effort 31,325lbf
Valve Gear Stephenson (piston valve)

In 1911 Robinson introduced a highly successful design of 2-8-0 locomotives on the Great Central Railway for hauling coal trains to the new docks at Immingham.

The GCR’s new port at Immingham was due to open in 1912, and new locomotives were required to haul the expected increase in coal traffic to Immingham from where it was exported. In August 1910, an order was placed for twenty locomotives based on Robinson’s existing Q4 0-8-0 but enlarged to give greater haulage capacity. The Q4 had already proven itself as a successful design that was robust and simple. The first GCR 8K (LNER O4/1 class) class locomotive (966) was built in September 1911. A superheated boiler was fitted of similar size to that used by Robinson on his C4 Atlantics. A leading pony truck was fitted to take the extra weight. The larger boiler was matched with an increase in cylinder diameter from 19in to 21in. The slide valves were replaced with piston valves of 10in diameter, positioned between the frames. As well as inheriting various design elements, the O4s also inherited the nickname ‘Tinies’ from the Q4s.

 q4 small Q4 class introduced by Robinson on the GCR in 1902
 c4 small C4 class introduced by Robinson on the GCR in 1903
 o4 small O4 class introduced by Robinson on the GCR in 1911

The new locomotives quickly proved a great success, and by 1914 six batches totalling 126 locomotives had been built. Three more were purchased by the GCR from the Ministry of Munitions in 1919, and all 129 would enter LNER ownership at Grouping (1923).

The O4’s boiler was of the same type as used on class B5, class C4, class C5, and class S1 locomotives. Designed for 200psi, it was actually operated at 180psi. The boiler was fitted with a Belpaire firebox. The prototype (GCR 966, BR 63572) was built with Robinson’s new 18 element superheater, introduced a few months earlier on an A5 4-6-2T. This superheater was based on the Schmidt design and was fitted to eight further O4s. Nine of the early O4s were also built with Schmidt superheaters, and four with a 24 element version of the Robinson superheater. This latter 24 element superheater became the standard for new O4s, although in 1916 it was decided to use 22 elements. Often 24 element superheaters were converted by merely blanking off two elements, although some waited until a boiler replacement was required. The 18 element and Schmidt superheaters were all replaced by Grouping.


 b5 small B5 class introduced on the GCR by Robinson in 1902
 c4 small C4 class introduced on the GCR by Robinson in 1903
 s1 small S1 class introduced on the GCR by Robinson in 1907
 a5 small A5 class introduced on the GCR by Robinson in 1911
 o4 small O4 class introduced by Robinson on the GCR in 1911

In 1918 eighteen more engines were built at Gorton with larger 6ft diameter boilers (GCR class 8M, LNER class 05) and they were known as the Tiny’s. They were later rebuilt with 5ft diameter boilers and were incorporated in the O4 class.

During the First World War the class was adopted by the Railway Operating Division (ROD) of the Royal Engineers as the standard type for war services. 521 locomotives were built by many different locomotive builders for service in France. The first orders for 325 locomotives were placed in February 1917 and these were followed by orders for 196 more in 1918 in order to keep British industry going during the post-war run-down in military manufacturing. They were almost identical to the GCR engines, but most of them were fitted with steel fireboxes that proved to have short lives. Some engines stayed in Britain and eventually all of those that travelled to France returned to Britain.

During First World War, the GCR class 8K (LNER class O4/1) was developed into the GCR class 8M (LNER class O5) by fitting a larger 5ft 6in boiler. This boiler was actually a shortened version of the boiler used on the B2 ‘Sir Sam Fay’ class with a 28 element superheater fitted. Two batches of ten were ordered, although these did not enter traffic until 1918 and 1921 respectively. Only nineteen 8Ms were built, with one of the first batch being built as the prototype 4-6-0 Class B6 (GCR Class 8N). The class 8M was not continued any further, and two of the 8M locomotives were rebuilt as 8Ks in 1922.

At the end of the war the engines were disposed of by the War Department. One hundred locomotives were purchased by the GWR (ROD class), fifty by the LNWR (all withdrawn by 1933). Others were sold overseas to China and Australia, where they were reported to be still at work in the late 1960s.

At Grouping in 1923, the LNER inherited 131 8K (LNER O4) and 17 8M (LNER O5) locomotives from the GCR. The ROD’s asking price for war-surplus locomotives had dropped, and the LNER was quick to add to its O4 fleet. 125 were purchased in December 1923, followed by 48 in February 1925, and a final purchase of 100 in February 1927 giving a total of 273 going to the LNER. The prices continued to drop, and the last purchase was for the amazingly low price of £340 per locomotive.

By 1929, the LNER’s stock of O4s totalled 405, including a further O5 that had been rebuilt as an O4 (leaving 15 remaining O5 class engines). The O5s were slowly rebuilt as O4s during the 1930s, with the last rebuild occurring in 1943. These were classified as O4/6.

World War 1 had led to an increase in the cost of coal and a deterioration in the quality. Hence Robinson became interested in the use of coal dust which also offered the promise of total combustion, and four O4s were used for pulverised fuel experiments between 1917 and 1924. The coal dust was gravity-fed into rotating feed screws at the bottom of the fuel container. Here, the fuel met a blast of air from a fan mounted at the front of the tender. The resulting gaseous mixture was fed through pipes to enter the back of the firebox via two 7.5in diameter holes in the foundation ring. The grate and ashpan were replaced with firebrick. The fans were fed by a De Laval steam turbine. The feed screws were initially powered by a four-cylinder petrol engine, but this was later replaced by a small steam engine. The entire arrangement needed an external source of steam to start a cold engine. Also, wartime conditions meant that investments in fuel preparation were limited. Coal dust was typically recovered from colliery screens and then dried over the flues of Lancashire boilers. Initial problems included getting the correct dust:air mixture. Problems with firebox size and design were also experienced. Colloidal fuel (dust/oil mixture) was also tried, but trials showed little advantage beyond a higher superheat temperature. Overall, the trials were not a success.


LNER locomotive in service


Built Number


1911-14 For GCR      126  126
1919 GCR bought from ROD (built at Gorton)           3  129
1923 LNER class O5 engines converted to LNER O4         2  131
LNER purchased from ROD     125  256
1925 LNER purchased from ROD       48  304
1926 LNER class O5 engines converted to LNER O4         1  305
1927 LNER purchased from ROD     100  405
1932-41 LNER class O5 engines converted to LNER O4       15  420
1941 Requisitioned for use in the Middle East      -92  328
1943 Last class O5 engine was converted to class O4         1  329
1944-47 Rebuilt as class O1 locomotives      -51  278
1947 Numbers taken into BR stock
·         O4/1       69
·         O4/2       11
·         O4/3     120  200
·         O4/4         0
·         O4/8       16    16
·         O4/5      8
·         O4/6    13
·         O4/7    41

The O4s were originally built with Robinson’s standard 1ft 10.25in high chimney. In 1923, one engine was fitted with a B7-type 1ft 3in chimney for trials in Scotland. Ten ex-ROD locomotives also had these chimneys fitted in 1924 for use in Scotland. The original Robinson chimneys had a tendency to crack, and they were gradually replaced from October 1923 with Doncaster “flowerpot” chimneys. From 1933, reduced-height domes and Gorton plain waisted 1ft 5.5in chimneys were fitted to the remaining unrebuilt O4s to bring them within the LNER’s Composite Gauge.

Doncaster had a clear preference for round-topped boilers, and there were a number of attempts to rebuild the O4s with round-topped boilers in-place of their Belpaire originals. Although the GCR had tried a similar reboilering in 1921, the LNER did not start until 1929 when two O4s were rebuilt with 5ft 6in boilers of the same type as used on the O2s. These rebuilds required frame extensions, and were classified as O4/4. In 1932, a shortened version of this boiler was produced, and was used on four O4s. Five further O4s were rebuilt with the new shortened boiler in 1939. All nine were classified O4/5. Also in 1939, a further shortening was applied to the boiler design, and was used in 47 O4 rebuilds by 1947. These were classified O4/7.

During the Second World War the War Department needed heavy freight engines so in September 1941 it requisitioned 92 LNER locomotives. Of these, 61 were RODs bought by the LNER in the mid-1920s after being used in France during the First World War and 31 were original GCR class 8K engines. They were shipped to Egypt and Palestine, where they worked on Egyptian State Railways, Palestine Railways, the Haifa, Beirut and Tripoli Railway between Palestine and Lebanon, the Chémin de Fer Damas-Hama et Prolongements in Syria, and Iraqi State Railways. Iraqi State Railways had six examples and designated them class RD: in March 1967 at least one remained in storage at Shalchiyah works outside Baghdad awaiting disposal. When the LNER renumbering scheme was drawn up the class was to be renumbered from 3500 upwards, with space left for the return of these engines. However, none of them did return after the Second World War and the LNER engines eventually became 3570-3920.

By the time 329 engines (including 51 class O1 engines) came into BR ownership they had all been fitted with flower-pot chimneys by Gresley and they were provided with a variety of different boilers. Five were sold to the War Department in 1952.

Number in Service under BR ownership.

Year End

Withdrawals Number in Service
O4/1 O4/5 O4/6 O4/7 O4/8




8  13  41  16




 199 7  13  41  16




 196 6  13  40  16


1950  196 6  13  40  16




6  13  40  16




 189 6  13  40  18




6  13  40  23




6  13  40  29




4  12  40  43




4  11  39  60




3  11  35  83




 119 2  11  34  99




   86  10  27  99




   82  10  24  99




   74    9  18  95




   27    7    7  75




   14    6    4  64




   10    3    3  41




     1  12





The 5 withdrawn in 1952 purchased by the British Government and were converted to oil burning and sent to the Suez Canal zone where they were used until 1955. They subsequently were used on the Egyptian State Railway until withdrawn in 1961.


 o4-1 small
O4/1  These were the original engines built with small GCR Belpaire boilers, steam vacuum brakes and 4,000 gallon tenders with water scoops.
O4/2  These were O4/3 engines with cab and boiler mountings reduced to fit the Scottish loading gauge. They were converted in 1925 onwards. Initially fitted with 3,250 gallon tenders but by 1925 they had 4,000 gallon tenders. They were reclassified O4/1 in December 1946.
O4/3  These were ROD engines with small Belpaire boilers, steam brake only and tenders without water scoops. They were reclassified O4/1 in 1947.


 o4-4 small
O4/4  This was the classification used for engines rebuilt by Gresley with O2 boilers between 1932 and 1939. The last of these was converted to O4/8 in 1947.
O4/8  Thompson also rebuilt some of the O4s, fitting the new cab and B1 boiler, but keeping the original valve gear and cylinders. These rebuilds were reclassified O4/8. A total of 99 O4/8s were built between 1944 and 1958.

The locomotives weighed 72t 10cwt.


 o4-5 small
O4/5 These were engines which were rebuilt from 1932 onwards by Gresley with shortened O2 type boilers with round top fireboxes and the smokebox on a saddle.

The locomotives weighed 74t 13cwt


 o4-6b small
O4/6 These were the original large boilered O5 class. They were rebuilt from 1924 onwards by Gresley with smaller Belpaire boilers, but still retained the Higher cabs.

63912-63920 of the O4/6 class had side window cabs.


O4/7 These engines were rebuilt from 1939 to 1944 by Gresley with shortened O2 type boilers with round top fireboxes. As such they were similar to the O4/5 class, but they retained their original GCR smokebox.

The locomotives weighed 73t 17cwt


 O1 small
O1 Thompson rebuilt fifty-eight engines from 1944 to 1949 by Thompson with 100A (B1 type) boilers, side window cabs, Walschaert valve gear and raised running plates.

Classified O1, they had a much more modern appearance and looked like a 2-8-0 version of the B1 class.

The locomotive weighed 73t 6cwt and had a superheated boiler with a pressure of 225psi. The tractive effort was 35,520lbf.

ROD locomotive in service


Comment Number


1917-19 Built by various contractors



1919 Surplus engines sold to GCR


Sold to GWR



1920 Sold to LNWR



1923 Sold to LNER



1925 Sold to GWR



Sold to LNER



1927 Sold to LMS



Sold to LNER



  • The 521 were built by-
    • North British Locomotive Company
    • Robert Stephenson & Co
    • Nasmith Wilson & Co
    • Kitson & Co
    • GCR at Gorton
  • Of the remaining 40-
    • 13 were sold to J&A Brown in New South Wales, Australia for use on the Richmond Vale Mining Railway. Three of these have been preserved.
    • It is unclear what happened to the other 27 but some of them went to China.
  • The LNWR and LMS engines, which were mainly bought to acquire the tenders, were all withdrawn from service by 1932. 30 of these were sold in 1932 to Armstrong Whitworth who sold them to China where they were known as class KD4 engines.
  • Of the 100 engines purchased by the GWR, 45 remained in service long enough to be taken into BR stock in 1948 as ROD class engines numbered 3002-3049. The last ones in service were withdrawn in October 1958. In January 1948 they were based at the following depots.




Cardiff Canton


Croes Newydd




Pontypool Road




St Phillips Marsh


Stafford Road










Gwr fitted GWR fitted version of the LNER O4 class
 gcr o1 small GCR class O4/1

Thompson became the LNER’s CME in 1941, and he quickly initiated his standardisation programme. This programme included a 2-8-0 mineral locomotive to replace the existing 2-8-0s, J19s, J20s, and J38s. Wartime austerity measures meant existing locomotives had to be rebuilt, so Thompson chose the O4 as a basis of his rebuilds. The existing frames and wheels were kept, but new Walschaerts valve gear, new cab and a raised running plate were fitted. The boiler and cylinders from the B1 4-6-0 were used. The new locomotives were classified as O1 and a total of 58 O4s were rebuilt between 1944 and 1949.

 j19 small J19 class introduced by Hill on the GER in 1912
 j20 small J20 class introduced by Hill on the GER in 1920
 j38 small J38 class introduced by Gresley in 1926
 b1 small B1 class introduced by Thompson in 1942
 O1 small O1 class introduced by Thompson in 1944 as a rebuild of class O4 engines.

Initial allocations of the O4s were to Gorton, Mexborough, Annesley, Retford, Stavely, Sheffield, and Immingham. Mexborough had the largest allocation, and would continue to do so until 1939. Sheds along the London Extension did not receive any O4s until 1914, when Neasden received three O4s to haul coal trains from Annesley to London. Mexborough O4s handled the bulk of the coal traffic over the Woodhead Route.

The LNER’s large purchases of ROD locomotives, meant the O4s fulfilled virtually all of the LNER’s heavy mineral locomotive requirements until Nationalisation (1948). The bulk of the O4s were located to the Southern Area (381 total), with small allocations to the North Eastern Area (24) and Scottish Area (16). Allocations tended to be to a greater range of sheds during the Second World War.

With the outbreak of World War 2, it was expected that the British Army would require O4s, and the LNER started to prepare 300 for requisition. 57 were prepared before the initial order was cancelled. All 57 returned to LNER service. In 1940, the GWR borrowed 30 O4s from the LNER. These returned between 1941 and 1943. In 1941, the military requisitioned 92 O4s (and 50 LMS 8Fs) for service in the Middle East. These opened up a supply route through Persia to Russia. None returned to Britain, and were written off the LNER’s books in December 1943. The final sale price of £5,700 to the British Government was finalised in 1947.


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