British Railway History Item
BR Class Riddles British Railways Standard Class 4 4-6-0
Built 1951-54. Designed by Robert A. Riddles.
Total Number Built 80.
Introduced 1951. Designed at Brighton. Classified 4MT.
(a) 75067-76079 Fitted with double chimney from 1957. BR1B tender.
(b) 75003/5/6/8/20/26/29 Fitted with double chimney from 1957. BR2 tender.
(d) 75000/2/4/7/9-19/21-25/27-28/30-49 Fitted with BR2 tender.
(e) 75050-75064 Fitted with BR2A tender.
75001/65-66 Fitted with BR1B tender.
Number Series 75000-75079.
Built at British Railway's Swindon Works.
No Lot Nos. yet available.
The Standard Class 4 4 6-0 is a lighter relation of the Standard Class 5, and is designed for almost universal availability over British main and secondary lines. Of existing types the locomotive is perhaps best compared with the Great Western Manor: With the same boiler pressure and driving wheel diameter, cylinders of similar dimensions save for a 28 in. stroke as opposed to the typical Western 30 in., identical coal and water capacity in the tender and total engine weight just a ton lighter the engine's principal gain over ita predecessor which will extend its range of action. is in maximum width below the running plate. Here it is 8 feet 7 3/8 inch over cylinders, as compared to the Manor's 8 feet ll? inch.
The boiler design is based on that of the standard L.M.R. Class 4MT 2-6-4 Tank, though the barrel is 9 inch longer and since the water is delivered into the boiler through clack-valves at 30 deg. from the boiler centre-line, the familiar top-feed casing is absent. The same modern aids to servicing are provided as on the 5MT : self-cleaning smoke-box, a rocking grate divided into two portions that can be rocked separately (but of seven sections in all in this case) and a self-emptying ashpan with two hoppers. The loco has a Western single note whistle in the conventional position ahead of the cab mounted on the manifold. The chime whistle is only fitted to the larger Standard engines.
The loco is fitted with plain bearing axleboxes to all wheels, and Timken roller bearings are found on the tender only, which resembles that of the Ivatt Class 2MT 2-6-0 in appearance. The 10 inch diameter piston valves are operated by conventional Walschaert valve gear, with a maximum travel of 7 11/32 inch at 77 per cent cut-off, and the reversing gear is of the same type fitted to the earlier BR Standard engines. Although the cab layout is generally similar to that of the Class 7MT Pacific and 5MT 4-6-0, the space is more restricted to suit a smaller loading gauge.
Designed at Brighton, with some additional work farmed out to Derby, Doncaster and Swindon, the class of 80 lightweight 4-6-0 locomotives were built at Swindon to work secondary main line traffic - both goods and passenger - on virtually any secondary route.
They continued the Standard family characteristics, established with ?Britannias? ,?Clans? and Standard Class 5s. Standardisation of locomotives and components was, of course, nothing new at the time, but the rail Nationalisation of 1948, bringing all the former disparate routes and administrations under ?one roof?, meant that an over-riding trend was set in motion for commonality within types operating over several administrations.
In part, the final designs were driven by a balance of higher availability and lower maintenance costs, the latter particularly pertinent in the British post-war climate, with both finance and manpower shortages as urgent factors. Other objectives were steam production capacity; simplicity of working parts, readily visible and easily accessible; the widest range of mixed traffic working; high level of bearing performance; mechanical lubricators; self-cleaning smokeboxes, rocking grates and self-emptying ashpans; engines to be sure-footed; and thermal efficiency, with large grates, low combustion and high degrees of superheat. Originally one of a list of twelve proposed standard types, the 4s shared the ?skirts above the knees? appearance of their sister classes, designed to give railmen as easy an access as possible.
The first loco entered traffic during May 1951 and was, in many respects, a tender version of the LMS 2-6-4 tanks built under Stanier and Fairburn (some of the latter were built at Brighton after nationalisation of the railways) but with the same smaller cylinders and higher pressure boilers of the Standard 4 tanks that started to leave Brighton works during July 1951.
In their day, the class replaced many ageing and obsolete types and in their many and varied wanderings around the country and with all manner or passenger and freight work, annual mileage of around 30-55000 was not unusual. In general, in addition, this mileage was accompanied by appreciative comments from footplatemen not known for lavish praise. Perhaps this was due in part to their allocation to points where such crew had been used to managing with worn-out cast-offs and, thus, new locomotives were to be welcomed. In turn, however, they too were replaced with the ever-quickening pace of the 1955 Modernisation Plan.
The first loco withdrawn was 75067 on 31 October 1964 from Eastleigh shed.
The last five locos withdrawn were 75009, 75019, 75020, 75027 and 75048 on 18 August 1968 from Carnforth shed, at the end of steam on BR.
Six locos are preserved - 75014, 75027, 75029, 75069, 75078 and 75079.
Motive Power Details
Weight: Loco 69 tons 0 cwt
50 tons 5 cwt BR1B 4,725 gallons, 7 tons coal
42 tons 3 cwt BR2 3,500 gallons, 6 tons coal (d)
42 tons 3 cwt BR2A 3,500 gallons, 6 tons coal (e)
Driving Wheel: 5' 8"
Boil Press: 225lb/sq in Su
Cylinders: Two 18" x 28" (outside)
Valve Gear: Walschaerts (piston valves)
TE: 25,100 lb
Overall Length: 60 ft
Class Total: 80
Allocation and Withdrawal Details
Last Updated : Monday 5th May 2003 11:52