British Rail HS4000

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HS4000 "Kestrel"
HS 4000 Barrow Hill Open Day 1971.jpg
HS 4000 at Barrow Hill Open Day 1971
Type and origin
Power typeDiesel-electric
BuilderHawker Siddeley, at Brush Traction, Loughborough
Serial numberBrush 711 (1967)[1][2]
Build dateCompleted In 1967
 • UICCo'Co'
Gaugeinitially 1,435 mm (4 ft 8 12 in) (UK)
after 1971 1,520 mm (4 ft 11 2732 in) Russian gauge[3]
Wheel diameter3 ft 7 in (1.092 m)[4]
1,092 mm (42.99 in)[3]
Wheelbase51 ft 8 in (15.75 m)[3]
Outer wheelset distance to middle axle: 7 ft 3 in (2.21 m)[1][3]
Inner wheelset distance to middle axle: 7 ft 8 in (2.34 m)[1]
Length66 ft 6 in (20.27 m)[3]
Width8 ft 9 34 in (2.69 m)
Height12 ft 9 34 in (3.91 m)
Axle load~22.2 long tons
21.5 t (after rebogying with Class 47 type bogies)
Loco weight133 long tons 6 hundredweight (135 t)[1][2][note 1]
126 t[3][note 2]
Fuel capacity1,000 imp gal (4,500 l; 1,200 US gal)
Prime moverSulzer 16LVA24[1]
Traction motors6 Brush Motors (DC)
Transmissionthree phase AC alternator, DC traction motors[1]
Train brakesDual (Air and Vacuum), electric regenerative dynamic brakes[1]
Performance figures
Maximum speed110 mph (180 km/h)
Power outputEngine: 4,000 hp (2,983 kW) @1100 rpm[1][3]
At rail: 2,500 kW (3,353 hp)[1]
Tractive effort450 kN (100,000 lbf)[3] maximum
270 kN (61,000 lbf) @ 30 km/h (19 mph)[3]
187 kN (42,000 lbf) @ 45 km/h (28 mph)[3]
OperatorsBritish Railways, Soviet Railways
DispositionExported to Russia, later scrapped.

HS4000, named Kestrel, was a prototype high-powered mainline diesel locomotive built in 1967 by Brush Traction, Loughborough as a technology demonstrator for potential future British Rail and export orders.[7] The locomotive number is a combination of the initials of Hawker Siddeley (the owners of Brush Traction) and the power rating of its Sulzer diesel engine (4000 HP).[7]

It was of Co-Co wheel arrangement and was fitted with a Sulzer 16LVA24 engine rated at 4,000 horsepower (3,000 kW) providing a maximum speed of 110 mph (180 km/h)[note 3] and weighed 133 tonnes. It was painted in a livery of yellow ochre with a broad chocolate-brown band around the lower bodyside separated by a thin white line running around the body.

Background and design[edit]

In the mid 1960s British rail produced specifications for type 5 locomotives weighing less than 126t with more than 3,000 hp (2,200 kW) of power for both passenger and freight working.[1] Brush Electric Engineering Ltd. (Brush Traction) in association with Sulzer Brothers Ltd. responded with a 4,000 hp (3,000 kW) locomotive for British Rail's appraisal. The design principle was that a single engine would require less maintenance than twin-engined vehicles, and that the very high power would mean that double heading for freight trains would be unnecessary.[1][2]

Diesel engine[edit]

Brush employed Sulzer's 16-cylinder Vee 16LVA24 engine made in Winterthur. Previous experience with Sulzer's 12-cylinder twin parallel-bank dual-crank 12LDA28 engine had gone well, but the highest power available from Sulzer in this form was the 12LDA31 of 2,350 hp (1,750 kW) see The Sulzer engine in diesel traction : A potted and incomplete history. Not only did the V engines provide over 3,000 hp (2,200 kW), but being single-crank with the consequently lighter engine block (over the dual-bank design) gave a better power-to-weight ratio.[8]

The engine is a four-stroke turbocharged oil-cooled design, with the oil being cooled by water in a heat exchanger, and the water cooled in radiators. The piston diameter is 240 mm with a stroke 280 mm.[3]

A smaller auxiliary generator (~40 kW[3]) was used to charge the batteries or start the engine etc.[1]

Electrical transmission and auxiliary electrical system[edit]

To transmit this power to the rail Brush utilised a brushless salient pole[note 4] three phase alternator connected to a rectifying circuit of 84 silicon diodes producing ~2,500 kW of power for electric traction from the diesel engine.[1][2] An auxiliary alternator, also brushless and producing three phase electrical power gave ~500 kW for electrical train heating, and also supplied power to electrical fans etc. in the locomotive.[1][2] The rotors for both alternators were electrically energised[note 5] by DC produced by the rectified output of brushless alternators.[1][2][note 6]

Each of the 6 axles were powered by its individual traction motor which were four pole force ventilated types. Connection of the axle to the motor was via a reduction gear (giving 110 mph (180 km/h) top speed), then through a flexible hollow shaft drive to the axle.[1][2]

The fans (blowers) to cool the traction motors and engine radiators were of the three phase asynchronous type, the motors driving the compressors, pumps, fans for the dynamic (resistive) brake etc. were DC motors.[1][2]

Braking system[edit]

Locomotive braking was by vacuum, air (high pressure) or dynamic (electrical regenerative resistive braking), the dynamic brakes were preferentially used at high speeds, with the air brake being activated at lower speeds where dynamic braking was less effective; speed sensors automatically determined the braking type to be used. Additionally a hydraulically activated parking brake was fitted.[1][2]

Electronic devices[edit]

Plug-in solid state modules were used for voltage and power control including monitoring wheelslip and monitoring engine temperature.[1][2]

Superstructure construction[edit]

A Warren truss body construction with welded, stressed steel skin was used on the sides of the locomotive which supported the transverse load of the main engine entirely.[1][2]


The bogie side frames were of one piece cast construction with coil spring suspension,[1][2] connected by 4 transverse members; two internal and two at either end[3]

After the Hither Green rail crash, British Rail issued a directive that all locomotives should have an axle weight of no-more than 21 tons. In an attempt to comply with this, Brush fitted the locomotive with modified British Rail Class 47 bogies. The lighter construction and traction motors helped but the attempt was ultimately unsuccessful leaving Kestrel at 22.5 tons per axle. Kestrel continued to be used but the axle-weight problem contributed to the decision to sell the locomotive and prior to this, in March 1971, the original bogies were refitted.


The driver's cab is attached to the frame below by rubber fittings.[3] Driver controls were similar to that of Class 47.[9]


British Rail[edit]

Construction of the locomotive (Brush works No. 711 of 1967) started in 1966 and was complete by 1967.[1] However the locomotive was considerably over the 20t axle-load limit specified by British Rail for its procurement requirements. The locomotive was officially handed over to BR on 29 January 1968 at Marylebone Station. Test runs were performed with both passenger and freight stock; the locomotive was primarily used to haul heavy freight trains - including a coal train of over 2000t weight[2] - the locomotive achieved an 88% availability figure after 14,000 miles (23,000 km).[1][2]

Following the fitting of its new bogies the locomotive was used on express passenger trains. On a London King's Cross to Newcastle service diagrammed for British Rail Class 55 ('Deltic') operation the unit was 14mins faster than required even though the new traction motors meant reduced power at the rail.[9]

In March 1971 it was withdrawn from service in the UK and sent back to Brush for refitting.

Sale to Soviet Union[edit]

The locomotive was sold to the Soviet Union in 1971 for £127,000,[2] being shipped from Cardiff Docks to Leningrad docks by the MV Krasnokamsk[9] in July 1971.[1] On arrival in Russia, Kestrel was exhibited at the Moscow Rolling Stock Exhibition and then was moved to the All-Union Rail Transport Scientific Research Institute at Shcherbinka[10] where it was re-gauged to 1,520 mm (4 ft 11 2732 in), and tested on a circular test railway[note 7] as well as being used on some parts of the Russian rail network.[3]

After testing of the locomotive the engine was removed for static testing, and the locomotive body ballasted for use in high load tests of other vehicles.[11]

The remains of the vehicle are believed to have been scrapped in 1993.[1]


United Kingdom[edit]

The locomotive did not result in any further orders.[12]


Some of the observations of Russian railway engineers relate to different practices between Russian and British locomotive design, specifically:

  • Due to the smaller loading gauges in Great Britain, the cab windows were set too low for signals to be seen if the driver is standing.
  • The passages were too narrow.
  • The bogies were considered overly large.
  • The requirement to sling the engine and compressor below the main frame considered unusual.
  • The stressed skin construction was noted as being not suitable due to corrosion increasing the susceptibility to structural weakening, as the load-bearing skin is thin and point welded.[11]

The axle bearings, traction transmission[13] and spherical rubber metal joints in the suspension[14] were considered of interest.[11]


Some of the HS4000's technology was used to form the basis of, or improvements in, subsequent locomotives built in the Soviet Union.[1][12]


HS4000 "Kestrel" is made as a kit and ready-to-run in OO gauge by Silver Fox Models.[15]

Heljan of Denmark have produced a highly detailed OO scale model of the Kestrel, as part of a limited run of 4000 units.[16]

The Swanley New Barn Railway, in Swanley, Kent, operates a 7 1/4 inch gauge overscale version of the 'kestrel' which was built by Mardyke Miniature Railways. Unlike the full size, this model is a diesel-hydraulic.[17]

References and notes[edit]


  1. ^ Weighed at Derby on 22 January 1968, producing an overweight result.[5]
  2. ^ Estimated, fully loaded, overall weight target.[6]
  3. ^ Sustained maximum speed, based on the traction motor gearing[2]
  4. ^ Salient-Pole Machines General description of salient pole machines as both motors and generators
  5. ^ i.e. not permanent magnet type
  6. ^ Thus the excitor alternators, and the main alternators's rotor were coaxial and connected, with the rectifying diodes also undergoing rotary motion
  7. ^ See ru:Экспериментальная кольцевая железная дорога ВНИИЖТ : Experimental test railway VNIIZhT in the Yuzhnoye Butovo District. VNIIZhT (ВНИИЖТ) is the Russian railway research institute of railway transport (Всероссийский научно-исследовательский институт железнодорожного транспорта)
    See Экспериментальное кольцо ВНИИЖТа Archived 12 September 2009 at the Wayback Machine. 'Experimental ring VNIIZhT'


  1. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z THE RAILWAY RAPTORS section HS4000 KESTREL
  2. ^ a b c d e f g h i j k l m n o p HS4000 "'KESTREL' : The world's most powerful Sulzer engined diesel locomotive" Check |url= value (help).
  3. ^ a b c d e f g h i j k l m n o Diesel HS400 (Kestrell) (Russian) information from "Локомотивы и моторвагонный подвижной состав железных дорог Советского Союза. 1966-1975", Ракова, Москва "Транспорт" 1979 г. (English:Locomotives and multiple train units rolling stock of railways of the Soviet Union. 1966-1975, Rakov, Moscow "transport" 1979)
  4. ^ Toms 1978, p. 76
  5. ^ Toms 1978, p. 77
  6. ^ Toms 1978, pp. 76–77
  7. ^ a b Recognition and Equipment information, HS4000
  8. ^ The Sulzer engine in diesel traction : A potted and incomplete history 1912 - 1990
  9. ^ a b c A Sulzer Engineer's Memories 1965-1979 On British Railways & Elsewhere section HS4000 "Kestrel"
  10. ^ Toms 1978, p. 82
  11. ^ a b c Тепловоз HS400 (Кестрелл) Diesel HS4000 Kestrel Author: Oleg Izmerov, Bryansk
  12. ^ a b The Railway magazine. August 2008, via
  13. ^ Измеров О.В. : ЛАССИФИКАЦИИ ТЯГОВЫХ ПРИВОДОВ ПО ДИНАМИЧЕСКИМ СВОЙСТВАМ ДЛЯ ЗАДАЧ ПРОЕКТИРОВАНИЯ РЕЛЬСОВЫХ ЭКИПАЖЕЙ Classification of vehicle traction drives by dynamic properties, Author:O V Izmerov, it is noted that the axial drive found in the 'Kestrel' locomotive gives lower horizontal and vertical track forces than an axle hung motor on a TEP75 locomotive at 160 km/h.
  15. ^ "HS4000 Kestrel Co-Co Brush". Archived from the original on 16 December 2013. Retrieved 17 November 2012.
  16. ^ "Brush/Hawker Siddeley KESTREL". (in Danish). Archived from the original on 16 February 2010. Retrieved 19 January 2010.
  17. ^ "Kestrel - HS4000". Retrieved 19 March 2011.


External links[edit]

  • "HS4000 in 1985". Photograph of HS4000 in Russia in a bad state of repair, still in Hawker Siddeley livery.