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British Railways Class 21 North British Locomotive Company Type 2 Bo-Bo Diesel

Class 21

Introduced in December 1958, this was a another fleet of pilot scheme Type 2 Locomotives built by the North British Locomotive Company and ordered under British Railways 1955 Modernisation Plan. They were designed for mixed traffic and came into service in 1958. The class was a diesel-electric design, but a similar class was built as a diesel-hydraulic for the Western Region, which were numbered in the D6300 series, later to be known as Class 22.

The initial order was for 10 locomotives, which were introduced between December 1958 and May 1959. However, the British Transport Commision saw fit to order afurther 48 locomotives before any were delivered: 28 for the Eastern Region and 20 for the Scottish region. Of the first 10 ordered, their first duties being on suburban trains on the Great Northern lines around London. After a short time, the Eastern Region locos were allocated to Hornsey, Ipswich and Stratford depots for service on former Great Eastern and London, Tilbury & Southend Lines. They proved unsuccessful on these duties and by March 1960 they could be seen sheeted over at Peterborough shed awaiting transfer to Scotland where they spent the rest of their working lives.

When first introduced, the locos had indicator discs at each end. A curiosity of these was that they folded sideways to accomodate the doors fitted for multiple working. The pilot scheme locos. were fitted with a different design of main grille to the rest of the locos. Most of the pilot scheme machines lost this grille to the normal design very soon after delivery. The livery on delivery was all-over BR loco Brunswick Green, with aluminium window frames on the cabs, roof panels (not the whole roof) in mid-grey and the roof fan grille in black. From 1964 onwards half-size yellow warning panels were introduced which covered most of the bottom half of the cab front (see photo of D6151 below).

Their first duties after transfer were on crew training, evening freight trains, to Carlisle and back. Some were then put to work on the fast passenger services between Glasgow and Aberdeen. These were the new flagship trains of the Scottish Region, boasting a 3 hour journey from Glasgow to Aberdeen. However, they were still not reliable enough to maintain a good service, even in pairs, which resulted in a return to steam haulage and the use of Gresley Streamlined A4 Pacifics on these trains.

In 1963, D6123 was selected as a test locomotive and sent to Davey Paxman's works in Colchester to have a new engine fitted, in an attempt to salvage something from these locos. The loco spent a few days at Carlisle Kingmoor shed on its journey south. After D6123 was rebuilt with its Paxman engine, it was put back to work on the the Glasgow to Aberdeen services. Due to poor reliability of the remaining locos, a further 19 were rebuilt during 1965 with new power units and reclassified along with D6123 as Class 29. When D6123 was rebuilt, it came out of the works with a new livery of two-tone green divided by a black stripe on the bodysides. The normal BR green covered the lower part of the bodyside and the lighter green, the same as on the Class 47, was applied to the top part of the body, above the crease, about half-way up. The other 19 locos that were converted carried a similar livery, except the black stripe was off-white instead. As well as a new livery, some minor bodywork changes were done on the rebuilt machines. One of the engine room windows, the one towards the main grille, was removed and a grille put in, together with another directly below it. The locos. were also fitted with headcode boxes vice the disc indicators and the communication doors were sealed up. These two changes also took place on a few of the unconverted machines.

D6109 received all-over BR blue livery with full yellow ends in 1967. None of the machines ever had TOPS numbers applied to them, which would be 21 0xx for a MAN-engined loco. or 29 0xx for a Paxman-engined examples.

Of the 38 machines that were not rebuilt, all were scrapped early. Quantity 29 were withdrawn in December 1967 and the remainder had all been withdrawn by the end of December 1971. The last three locos withdrawn were D6111, D6117 and D6152 in August 1968 from Glasgow Eastfield shed. The first disposal was D6136, cut up by Barnes & Bell at Coatbridge in April 1968. All the remainder were cut up for scrap by the end of 1969 with the exception of D6122 which lasted until June 1980 finally being cut up at Woodham Brother's, Barry scrapyard.

BUILT: 1958-60 by the North British Locomotive Company, Glasgow.

Initial Allocations

Hornsey 34B (10)
Ipswich 32B (18)
Kittybrewster 61A (19)
Stratford 30A(10)

SPECIFICATION FOR 10 PILOT LOCOS.

ENGINE: NBL/MAD L12V18/21 1,100hp (Derated to 1,000hp).

TURBOCHARGERS: Napier

NUMBER SERIES: D6100-D6157.

PREVIOUS NUMBERS: Nil.

CYLINDERS: 12

CYCLE: four-stroke

TRANSMISSION: .

MAX SPEED: 75mph. Availability of full engine output between 4.3 and 75mph.

TRACTIVE EFFORT: 45,000lb at 28% adhesion at 2,800A main generator.

CONTINUOUS TE: 25,000lb at 11 mph at 1,700A main generator'

WEIGHT: 73 tons.

WHEEL ARRANGEMENT: Bo-Bo.

MAIN GENERATOR: GEC WT880.

TRACTION MOTORS: four GEC WT440, nose suspended.

GEAR DRIVE single reduction.

CONT: rail hp 733.

LOCO BRAKES: air.

TRAIN BRAKES: vacuum, giving brake force of 84% of loco weight in working order.

MIN RADIUS CURVE: 4.5 chains without gauge widening at dead slow speed.

TRAIN HEATING: Spanner Swirlyflo vertical boiler giving a teaming capacity of 1,500lb/h.

Engine fuel capacity 360 gal.

Boiler fuel capacity 100 gal.

Boiler water capacity 600 gal

SPECIFICATION FOR PRODUCTION LOCOS (with MAN engine).

ENGINE: NBL/MAN L12V18/21BS 1,100hp (Derated to 1,000hp).

TURBOCHARGERS: Napier.

NUMBER SERIES: D6100-D6157.

PREVIOUS NUMBERS: Nil.

CYLINDERS: 12.

CYCLE: four-stroke.

TRANSMISSION:

MAX SPEED: 75mph. Availability of full engine output between 5.2 and 64 mph.

TRACTIVE EFFORT: 45,000lb at 28% adhesion at 2,800A main generator.

CONTINUOUS TE: 30,000lb at 10.2 mph at 1,940A main generator.

WEIGHT: 73 tons.

WHEEL ARRANGEMENT: Bo-Bo.

MAIN GENERATOR: GEC WT880A.

TRACTION MOTORS: four GEC WT440, nose suspended.

GEAR DRIVE single reduction.

CONT: rail hp 816.

LOCO BRAKES: air.

TRAIN BRAKES; vacuum, giving brake force of 84% of loco weight in working order.

MIN RADIUS CURVE: 4.5 chains without gauge widening at dead slow speed.

TRAIN HEATING: Spanner Swirlyflo vertical boiler giving a teaming capacity of 1,500lb/h.

Engine fuel capacity 360 gal.

Boiler fuel capacity 100 gal.

Boiler water capacity 600 gal.

QTY BUILT : 58.

CURRENT FLEET STRENGTH: NIL (All Withdrawn - None Preserved).

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Last Updated : Monday 2nd June 2014 03:18

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