S&DJR 7F 2-8-0

S&DJR 7F 2-8-0
LMS 13809, a preserved 7F locomotive, working the Hellifield to Carnforth leg of a Cumbrian Mountain Pullman in 1983.
Specifications
Power type	Steam
Designer	Henry Fowler
Builder	Midland Railway, Derby Works (1914), Robert Stephenson & Co. (1925)
Serial number	RS 3892–3896
Build date	1914 (6), 1925 (5)
Total produced	11
Configuration	2-8-0
UIC classification	1′D h2
Gauge	4 ft 8 1⁄2 in (1,435 mm)
Driver diameter	4 ft 7 1⁄2 in (1,410 mm)
Minimum curve	6 chains (400 ft; 120 m) normal 4.5 chains (300 ft; 91 m) dead slow
Weight on drivers	56 tons 0 cwt (125,400 lb or 56.9 t)
Locomotive weight	64 tons 15 cwt (145,000 lb or 65.8 t)
Tender weight	42 tons 14 cwt (95,600 lb or 43.4 t)
Fuel type	Coal
Boiler	G9AS or G9BS
Boiler pressure	190 lbf/in2 (1.31 MPa)
Firegrate area	28.4 sq ft (2.64 m2)
Heating surface: – Total	G9AS: 1,681 sq ft (156.2 m2) G9BS: 1,845 sq ft (171.4 m2) (both include superheater)
Cylinders	Two, outside
Cylinder size	21 in × 28 in (533 mm × 711 mm)
Valve gear	Walschaerts
Valve type	Outside admission piston valves
Tractive effort	35,295 lbf (157.00 kN)
Factor of adhesion	3.5
Locomotive brake	Steam
Train brakes	Vacuum
Career
Railroad(s)	SDJR » LMS » British Railways
Power class	SDJR: 5P/5G LMS: 7F
Number	S&DJR: 80–90; LMS: 9670–9680; later 13800–13810; BR: 53800–53810
Withdrawn	1959–1964
Disposition	Two preserved, nine scrapped

53809, at Green Park Station (now a car park) in Bath Spa, 6th March 2006.

No. 53809 crosses the Butterley Reservoir causeway on the Midland Railway - Butterley

The Somerset and Dorset Joint Railway (S&DJR) 7F 2-8-0 is a class of steam locomotive designed for hauling heavy coal and goods trains. Eleven were built in two batches in 1914 and 1925, and were used until withdrawn between 1959 and 1964. Two are preserved.

Background

The Midland Railway, joint owners of the S&DJR with the London and South Western Railway (L&SWR), were in charge of locomotive policy on the line. The S&DJR which was highly graded and required power over and above what was available from the Midland's small engines. M. H. Ryan, S&DJR locomotive superintendent argued for a type specific to the line.

Two plans for 0-8-0s were suggested in 1907 but would have been too heavy. Clearly a special exception to the small engine policy, James Clayton the draughtsman at Derby was given a free hand to design the engine, and produced something unlike any other Derby-designed locomotive of the time.

Design

The design used the G9AS boiler from the Midland Compounds, with a Belpaire firebox and Walschaerts valve gear. A leading pony truck was added, to distribute the weight, making it a 2-8-0. The cylinders were mounted high on the frame, and sloped, to avoid fouling platforms. Because of the gradients that the loco would face, Clayton provided two steam brake cylinders on the engine and a further one on the tender. The Derby standard axle boxes were fitted, so the engines were still subject to the hot boxes that were a fact of life on the Midland. As the locomotives were initially too large for some of the turntables, it was envisaged that they would spend half their time travelling in reverse. Consequently, they were fitted with tablet exchanging apparatus on both sides of the locomotive. In addition, the first six were equipped with cab tenders, but these were later removed circa 1920.^[1] The 1914-built locomotives were right-hand drive, while the 1925-built were left-hand drive. In all cases the vacuum brake ejector was located on the driver's side of the smokebox.

Construction

Six were built in 1914 and numbered 80–85 by the S&DJR. In 1925 an additional 5 were ordered from Robert Stephenson and Company in Darlington and built with the larger G9BS boilers, becoming numbers 86–90. Two locomotives, 9679 (ex-89) and 9680 (ex-90) received the smaller G9AS boiler in 1930, while the remaining three retained the larger boiler until it was replaced in the 1950s – 53808 in 1953; 53807 in 1954; and 53806 in 1955. These locomotives gained a packing piece between the smaller boiler and original smokebox saddle. The exception was 53807, the smokebox saddle being rotten and replaced with a one-piece unit like the 1914-built locomotives. This locomotive was therefore unique, as only left-hand drive locomotive with a one piece smokebox saddle.

East Midlands trials

Their success on the Mendip hills prompted the Midland to try them on the East Midlands coal trains, but they were not so satisfactory. They were, after all, designed for climbing hills, but perhaps the reasons were fuel efficiency, for they consumed considerable amounts of high quality coal.^[2]

Later life

53808 at Bath Green Park shed in 1964

The S&DJR locos were taken into London, Midland and Scottish Railway (LMS) stock in 1930, and renumbered 9670–9680. They were renumbered as 13800–13810 in 1932. On nationalisation in 1948 British Railways (BR) added 40000 to their numbers making them 53800–53810.

Withdrawals of the 1914-built locomotives occurred between 1959 and 1962 and the five 1925-built engines were all withdrawn between 1963 and 1964.

Preservation

Two have survived, 88 (9678/13808/53808) on the West Somerset Railway and 89 (9679/13809/53809) at the Midland Railway - Butterley. No. 88 returned to service in December 2005 and is painted in S&DJR blue livery, which it never carried in service. No. 89's latest overhaul was completed in January 2006, and the locomotive emerged in BR Black Livery as No. 53809 (with Late Crest), entering service in early February at the Midland Railway - Butterley.

Both met for the first time in preservation at the West Somerset Railway during the next month, after No. 89 made a return to Bath Green Park Station over March 5 and 6th 2006, 40 years after the S&D closed.

References

External links

Wikimedia Commons has media related to S&DJR Class 7F.

• Information about the class from S&DJR trust
• Rail UK database
• Heißdampf-Güterzuglokomotive der Sommerset—Dorset-Verbindungsbahn mit Rauchröhrenüberhitzer Patent Schmidt from Die Lokomotive (German)