British Rail Class 21

Infobox Locomotive
name = North British Type 2 diesel-electric
British Railways Class 21
powertype = Diesel-electric


caption =
roadnumber = D6100–D6157
builder = North British Locomotive Co.
builddate = 1958–1960
totalproduction = 58
gauge = RailGauge|ussg|lk=on|al=on
primemover = MAN L12V18/21S
tractionmotors = GEC WT440, 4 off
transmission = DC generator, DC traction motors
whytetype = Bo-Bo
uicclass = Bo'Bo'
wheeldiameter = convert|3|ft|7|in|m|3|abbr=on
minimumcurve = convert|3.5|chain|m|lk=in
trainbrakes = Vacuum
locobrakeforce = convert|50|LTf|kN|sigfig=2|abbr=on|lk=in
wheelbase = convert|37|ft|0|in|abbr=on
length = convert|51|ft|6|in|abbr=on
width = convert|8|ft|8|in|abbr=on
height = convert|12|ft|8|in|abbr=on
weight = convert|72.50|LT|sigfig=3
topspeed = convert|75|mph|abbr=on|lk=on
poweroutput = "Engine:" convert|1000|hp|0|abbr=on|lk=on or convert|1100|hp|0|abbr=on
tractiveeffort = "Maximum:" convert|45000|lbf|kN|1|abbr=on|lk=on
fuelc
convert|460|impgal|abbr=on|lk=on
trainheating = Spanner convert|1500|lb per hour Steam generator
multipleworking = "D6100–D6137:" ● Red circle
"D6138–D6157:" ★ Blue star
axleloadclass = Route availability 6 (5 from 1969)
railroad = British Railways
retiredate = 1967–1968
disposition = 20 rebuilt to class 29, remainder scrapped:"This is article is about diesel locomotives built 1958-1960; For 2007-era locomotives, see Vossloh G1206.The North British Type 2 diesel-electric (later known as British Railways’ Class 21) was a type of diesel locomotive built by the North British Locomotive Company in Glasgow for British Railways in 1958-1960.

Starting in 2007, the classification has been reused for new Vossloh G1206 acquired by Euro Cargo Rail/EWS.

Description

Under the British Railways Modernisation Plan, a batch of ten Convert|1000|hp|kW|sigfig=3|abbr=on diesel-electric locomotives for evaluation under the pilot scheme. At the same time, six similar locomotives employing hydraulic transmission were ordered for comparison, these becoming Class 22. Repeat orders resulted in a total of 58 of the diesel-electric locomotives being built (numbered D6100–6157). They were delivered between December 1958 and November 1960.

The first 38 locomotives entered service from the Eastern Region depots at Stratford, Hornsey and Ipswich on commuter services into London, where they were evaluated against rival designs from English Electric, British Railways, Birmingham RC&W and Brush. The final 20 locomotives had uprated Convert|1100|hp|kW|sigfig=3|abbr=on engines and were delivered to Kittybrewster depot on the Scottish Region.

Unfortunately, they proved to be extremely unreliable in service, and by the end of 1960 the Eastern Region fleet was transferred to Eastfield depot on the Scottish Region for convenience of return to their manufacturer when warranty work was required. However, North British Loco closed down in 1962, by which time the type’s principal shortcomings had become plain. In particular there were problems with the coupling between the power unit and the generator. The engines themselves were a MAN design, but which were license-built by NBL and of inferior quality to the German originals.

In an attempt to improve reliability, 20 locomotives, (D6100–03, D6106-D6108, D6112–D6114, D6116, D6119, D6121, D6123, D6124, D6129, D6130, D6133, D6134, D6137), were re-engined between 1963 and 1965 with Convert|1350|hp|kW|sigfig=3|abbr=on Paxman engines to form Class 29.

The remaining 38 locomotives retained their original NBL/MAN engines until they were withdrawn from service between December 1967 and August 1968 and sold for scrap. Most were quickly cut up by Scottish scrap dealers McWilliams of Shettleston or Barnes and Bell of Coatbridge, but locomotive D6122 was sold to Woodhams' Scrapyard in Barry, South Wales, where it languished until 1980 before being broken up. None have survived.

ources

*cite book | last = Stevens-Stratten | first = S.W. | coauthors = Carter, R.S. | title = British Rail Main-Line Diesels | publisher = Ian Allen Ltd | date = 1978 | location = Shepperton | isbn = 0 7110 0617 2
*Ian Allan ABC of British Railways Locomotives, summer 1966 edition
*cite book | last = Sugden | first = S.A. | title = Diesel & Electric Loco Register (3rd edn) | publisher = Platform 5 | location = Sheffield | isbn = 1 872524 55 9
*cite book | last = Grindlay | first = Jim | title = British Railways Locomotive Allocations 1948-1968 (Part 6 - Diesel & Electric Locomotives) | publisher = Modelmaster Publications | location = Troon | isbn = 978 0 9544264 6 0