37901

37901 in its original
form as 37150

Above: 37901, in its previous guise as 37150, at Polmadie Depot on 2nd March 1980. (Martin Bray)

37901, then numbered D6850, was delivered from English Electric to Cardiff Canton in 1963.

During the 1980s, a requirement for a new type of medium power diesel loco was identified; a replacement for the then ageing but still reliable class 37. At the time the decision was also taken to refurbish many of the existing class 37 fleet, including numerous improvements. Some were fitted with electric train heat, whilst others were intended for freight use and some had ballast weights for improved adhesion.

Six locomotives were chosen as testbeds for alternative power units to be evaluated for the proposed class 37 replacement. D6850, by then renumbered 37150, was one of the six; the existing English Electric power unit was replaced by a Mirrlees engine of similar rating. 37150 then became 37901, and was named Mirrlees Pioneer at Cardiff Canton where it was then based.

After conversion to
37901

Above: 37901 stored at Cardiff Canton awaiting disposal on 11th June 2000. (Martin Bray)

The six converted locomotives worked diagrams out and back from their South Wales home, and were generally well regarded, apart from being slow to start with a heavy load, earning them the nickname 'Slugs'.

However there were major changes in the rail industry, including the onset of privatization; meanwhile the refurbished class 37 locomotives were giving excellent performances. The new build project was abandoned, leaving the class 37/9 fleet as a small class that were expensive to maintain due to their non-standard nature. They were gradually withdrawn, 37901 towards the end of 1998. It has since been bought by a private owner for preservation.

General Info

Built

English Electric, 1963

Lot no.

???

Engine

Mirrlees MB275T of 1800hp at 1000rpm

Transmission

Electric - six English Electric 538/A axle-hung motors

Power at Rail

1300hp

Tractive Effort

62680lbf

Wheels

Co-Co

Weight

120t

Max Speed

80mph

Train Brakes

Vacuum and air

Train Heat

None

Depot and Sector Allocations

Cardiff Canton

86A

06/1963

Haymarket

HA

09/1966

Eastfield

ED

05/1970

Renumbered from D6850 to 37150

04/1974

Motherwell

ML

11/1979

Eastfield

ED

01/1984

Motherwell

ML

18/11/1984

Cardiff Canton

CF

03/1985

Stratford

SF

24/11/1985

Cardiff Canton

CF

16/02/1986

Renumbered to 37901

30/10/1986

Named Mirrlees Pioneer

03/12/1986

Freight Metals Cardiff class 37/9 pool

FMCC

01/01/1989

Freight Metals Cardiff Canton class 37/7 and 37/9 pool

FMHK

15/04/1990

Trainload Metals Cardiff class 37/9 reserve pool

FMMK

25/04/1993

Freight Metals Cardiff Canton class 37/7 and 37/9 pool

FMHK

22/08/1993

Trainload Freight West - CF class 37/9 (Wales)

LNHK

20/03/1994

Trainload Freight West - CF class 37 (South Wales)

LNCK

27/09/1996

Headquarters - EWS stored main line locomotives

WNXX

06/11/1998

EWS - main line locomotives for component recovery

WNYX

10/12/1999

EWS - locomotives for disposal

WNZX

07/06/2002

Llangollen

02/10/2003

This locomotive is operated by the diesel group. Thanks to the Class 37 locomotive group for historical information and Martin Bray for photos.

Transferred 11th Sept 2007 by John Rutter - email webmaster

37901 in Pentrefelyn Carriage Shed having a final repaint before the naming as Mirrlees Pioneer 11th March 2006

Photo John Rutter

37901 named as “Mirrlees Pioneer” after the naming ceremony in Llangollen Station on 11th March 2006

Photo John Rutter