Cromwell tank

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Tank, Cruiser, Mk VIII, Cromwell (A27M)
Puckapunyal-Cromwell-2.jpg
A Cromwell Mk. 1 displayed at the Royal Australian Armoured Corps Tank Museum, Puckapunyal, Australia (2007). The white writing on the turret is to inform cargo handlers that it is not to be transported by sea as deck cargo
Type Cruiser tank
Place of origin United Kingdom
Service history
In service 1944–1955
Used by British Army, Israeli Army, Greek Army, Portuguese Army
Wars World War II, 1948 Arab–Israeli War, Korean War
Production history
Designer Leyland, then Birmingham Railway Carriage and Wagon Company from 1942[1]
Manufacturer Nuffield Mechanisation and Aero
Number built 4,016
Specifications
Weight 27.6 long tons (28 tonnes)
Length 20 ft 10 in (6.35 m)
Width 9 ft 6 12 in (2.908 m)
Height 8 ft 2 in (2.49 m)
Crew 5 (Commander, gunner, loader/radio operator, driver, front gunner)

Armour 3 inches (76 mm)
Main
armament
Ordnance QF 75 mm
with 64 rounds
Secondary
armament
2 x 7.92 mm Besa machine gun
with 4,950 rounds
Engine Rolls-Royce Meteor V12 petrol
600 horsepower (450 kW)
Power/weight 21.4 hp/tonne
Transmission Merritt-Brown Z.5 gearbox (five forward and one reverse gear) driving rear sprockets
Suspension Improved Christie
Ground clearance 16 inches
Fuel capacity 110 gallons + optional 30 gallon auxiliary
Operational
range
170 miles (270 km) on roads, 80 miles cross country[2]
Speed 40 miles per hour (64 km/h) with 3.7:1 final reduction drive

Tank, Cruiser, Mk VIII, Cromwell (A27M),[nb 1] and the related Centaur (A27L) tank, were one of the most successful series of cruiser tanks fielded by Britain in the Second World War. The Cromwell tank, named after the English Civil War leader Oliver Cromwell, was the first tank put into service by the British to combine a dual-purpose gun, high speed from the powerful and reliable Meteor engine, and reasonable armour, all in one balanced package. Its design formed the basis of the Comet tank.

The Cromwell and Centaur differed in the engine used. While the Centaur had the Liberty engine of the predecessor cruiser tank, the Crusader (and the interim A24 Cavalier), the Cromwell had the significantly more powerful Meteor. Apart from the engine and associated transmission differences, the two tanks were effectively the same and many Centaurs built were given the Meteor to make them Cromwells.

The Cromwell first saw action in the Battle of Normandy in June 1944. The tank equipped the armoured reconnaissance regiments, of the Royal Armoured Corps, within the 7th, 11th, and Guards Armoured Divisions. While the armoured regiments of the latter two divisions were equipped with M4 Shermans, the armoured regiments of the 7th Armoured Division were fully equipped with Cromwell tanks. The Centaurs were not generally used for combat except for those fitted with a 95mm Howitzer which were used in support of the Royal Marines during the invasion of Normandy.

Development[edit]

The Cromwell and the related Centaur were the product of further development of British cruiser tanks, and they were designed as the replacement for the Crusader tank, which although not yet in service would become obsolete in time. In late 1940, the General Staff set out the specifications for the new tank, and designs were submitted in early 1941. The tank would be fitted with the QF 6 pounder gun with the expectation that it would enter service in 1942.

Due to the typical rushed production and lack of components, the A24 Cavalier, then known as "Cromwell I", built by Nuffield had far too many problems to see active combat service. One of the key problems was that its Nuffield-built Liberty engine was simply not up to the task. It had been ordered as it was based on tried equipment and therefore should have entered service with minimal delay.

Leyland and Birmingham Railway Carriage & Wagon (BRC&W) had been involved in the development and had offered similar designs to Nuffield. A second specification for a better tank was the General Staff A27. The tank would be fitted with the QF 6 pounder gun with the expectation that it would enter service in 1942. Once it became clear there would be delays, a programme was set in place to fit the 6 pounder to the Crusader to get some 6 pounder tanks in service.[3]

At the same time, a new engine was designed to be a tank powerplant. The Meteor engine was based on the powerful Rolls-Royce Merlin engine used in aircraft such as the Spitfire. Rolls-Royce, Leyland and BRC&W produced a prototype by January 1942 based on the Crusader but using the Meteor. With nearly 600 hp (450 kW) it proved to be exceptionally mobile when trialled. Leyland were lined up to produce the Meteor but withdrew in mid-1941 as they had doubts about being able to provide sufficient cooling. Rolls-Royce, the makers of the Merlin, were already fully committed to manufacturing the Merlin and could not spare the facilities for the Meteor, and so manufacture was passed to the Rover Car Company.[4]

The General staff issued new specifications to cover the tanks. The BRC&W design using the Meteor was A27M (or "Cromwell III") and Leyland's version of it to take the Liberty was A27L ("Cromwell II"). Nuffields A24 with the Liberty was the Cromwell II. The naming was reworked in November 1942 with the A27L as Centaur, A27M as Cromwell and A24 as Cavalier.

Production began in November 1942. It would take considerable time for Rover to make ready production lines for the Meteor, and it was not until a few months later, in January 1943, that sufficient Meteor engines were available and the A27M Cromwell began production. The Centaur production design allowed for the later conversion to the Meteor engine and many Centaurs would be converted to Cromwells before use.

Design[edit]

Silhouettes of M4 Sherman (top) and Cromwell (bottom) together

The frame was of riveted construction, though welding was used later. The armour plate was then bolted to the frame; large bosses on the outside of the plate were used on the turret. Several British firms besides Leyland contributed to production of the Cromwell and Centaur, including LMS Railway, Morris Motors, Metro-Cammell, Birmingham Railway Carriage and Wagon Company and English Electric.[2] Some variants were produced with 14-inch-wide (360 mm) tracks; later, 15.5-inch tracks were used.

The suspension was of the Christie type, with long helical springs (in tension) angled back to keep the hull sides low. Of the five road wheels each side, four had shock absorbers. The tracks were driven by sprocketed wheels at the rear and tension adjusted at the front idler, this being standard British practice. As with previous Christie-suspension cruiser tanks, there were no track return rollers, the track being supported instead on the tops of the road wheels. The side of the hull was made up of two spaced plates, the suspension units between them, and the outer plate having cutouts for the movement of the road-wheel axles. The gearbox had five forward and one reverse gears. The first gear was for "confined spaces, on steep inclines or...sharp turns".

The Meteor engine delivered 540 hp at 2,250 rpm. This was the maximum rpm, which was limited by governors built into the magnetos. Fuel consumption on "pool" petrol (67 octane) was between 0.5 and 1.5 miles per gallon depending on terrain.

The driver sat on the right in the front of the hull, separated from the hull gunner by a bulkhead. The driver had two periscopes and a visor in the hull front. The visor could be opened fully or a small "gate" in it opened; in the latter case a thick glass block protected the driver. A bulkhead with access holes separated the driver and hull gunner from the fighting compartment. A further bulkhead separated the fighting compartment from the engine and transmission bay. The engine compartment drew cooling air in through the top of each side and the roof and exhausted it to the rear. To allow fording through up to 4 ft (1.2 m) deep water a flap could be moved over to cover the lowermost air outlet.[5] Air for the engine could be drawn from the fighting compartment or the exterior; it was then passed through oil bath cleaners.

The Cromwell still had revisions to make before service, most notably changing from the QF 6-pounder (57 mm) to the ROQF 75 mm gun, which was an adaptation of the 6 pounder design to fire the ammunition of the US M3 75 mm gun, which gave it a better HE round to use in infantry support. This meant that the 75 would use the same mounting as the 6 pounder. In June 1944 the Cromwell first saw action during Operation Overlord, the Allied invasion of Normandy. It had a mixed reception by crews. It was faster and had a lower profile than the Sherman tank and thicker frontal armour; 3 in (76 mm) versus the 2 in (51 mm) of the Sherman. On later Cromwells this was increased incrementally, first to 3 14 in (83 mm), then finally to 4 in (100 mm). The 75 mm gun, though able to fire a useful HE shell, was not as effective against armour as the 6 pdr or the Ordnance QF 17 pounder gun. A derivative of Cromwell, the Cruiser Mk VIII Challenger, was built to take the 17 pounder; only a small number were built. In practice, the majority of the 17-pounder armed tanks to see service in the war were Firefly variant of the Sherman.

There was a 7.92 mm Besa machine gun mounted co-axially to the main armament operated by the gunner. A second was "gimbal" mounted in the front of the hull. The mounting gave 45 degrees of coverage to the front (it had 25 degrees of vertical movement as well) and sighting was by a No. 35 telescope which was connected through a linkage to the mounting.

In the top of the turret was mounted a 2 inch "bombthrower" angled to fire forward. Thirty smoke grenades were carried for it.

Production[edit]

Total A27 production consisted of 4,016 tanks, 950 of which were Centaurs and 3,066 Cromwells. In addition, 375 Centaur hulls were built to be fitted with an anti-aircraft gun turret; only 95 of these were completed.

Combat service[edit]

Wounded German soldiers being ferried to an aid post on the hull of a Cromwell tank

The Centaur was chiefly used for training; only those in specialist roles saw action. The Close Support version of the Centaur with a 95 mm howitzer replacing the 75mm saw service in small numbers as part of the Royal Marine Armoured Support Group on D-Day, and a number were used as the basis for combat engineering vehicles such as an armoured bulldozer.

The Sherman remained the most common tank in British and Commonwealth armoured units. Cromwells were used as the main tank to equip the armoured brigades of only one division, the 7th Armoured Division, although the Cromwell was used as the main tank in the armoured reconnaissance regiments of British armoured divisions (Guards Armoured Division and 11th Armoured Division)[6] in North West Europe, because of its speed and relatively low profile. The Cromwell in turn was succeeded by small numbers of the Comet tank. The Comet was similar to the Cromwell, being based on it[7] and shared some components, but had a superior gun in the 77 mm gun (a version of the 17 pounder with different ammunition).

In general the Cromwell was found to be very reliable with excellent speed and manoeuvrability though it required more maintenance than the Sherman. It was given a modification to the exhaust to redirect fumes so that they were not drawn into the fighting compartment, a problem found when tanks were drawn up together preparing for an advance.[8]

In northern Europe, the Cromwell was used by Allied units of the 1st Polish Armoured Division (10th Mounted Rifle Regiment)[9] and Czech Armoured Brigade.

After the war, the Cromwell remained in British service, and saw service in the Korean War with 7 RTR and the 8th King's Royal Irish Hussars.

The Cromwell/Centaur had the distinction of being the first tank to go into service with the Greek Army during the re-formation following the Second World War. Fifty-two Centaur I tanks were donated early in 1946, during the opening stages of the Greek Civil War, but they were kept in storage due to the lack of trained personnel. In 1947 the first Greek officers returned from training courses in the United Kingdom and training of tank crews began. The Centaur saw limited service in the civil war, as during the last year of the war (1949) battles were fought on mountains. Centaurs formed the core of the Greek Armour Corps during the 1950s, and were retired in 1962, having been replaced by US-built M47s.

Finland used the Charioteer version of the Cromwell post war.

Operators[edit]

Performance[edit]

The Cromwell was the fastest British tank to serve in the Second World War[citation needed], with a top (ungoverned) speed of 40 mph (64 km/h). However, this speed proved too much for even the Christie suspension and the engine was governed to give a top speed of 32 mph (51 km/h), which was still fast for its time. Thanks to its excellent engine power and Christie parentage the Cromwell was very agile on the battlefield. The dual purpose 75 mm main gun fired the same ammunition as the US 75 mm gun and therefore it had around the same HE and armour-piercing capabilities as the 75 mm equipped Sherman tank. The armour on the Cromwell ranged from 8 mm up to 76 mm thick overall. However, on all-welded vehicles built by BRCW Co. Ltd, the weight saved by the welding allowed for the fitting of appliqué armour plates on the nose, vertical drivers' plate and turret front, increasing the maximum thickness to 102 mm. In period photos, these vehicles are identified by their War Department numbers carrying the suffix W, e.g. T121710W. This armour compared well with that of the Sherman, although the Cromwell did not share the Sherman’s sloped glacis plate. The Cromwell crews in North-West Europe succeeded in outflanking the heavier and more sluggish German tanks with superior speed, manoeuvrability and reliability. However, the Cromwell was still not a match for the best German armour and British tank design would go through another stage, the interim Comet tank, before going ahead in the tank development race with the Centurion tank.


Variants[edit]

Cromwell tank hierarchy.png

The modifications and developments of the Cromwell were classified under "Type" and "Mark". A single Mark could cover up to four Types and a Type up to six Marks making classification complex.[10]

The Types ran from A (the earliest Cavaliers, Centaurs and Cromwells) to F (a late model Cromwell with driver's side escape hatch).

Centaur I
First draft. Armed with the Royal Ordnance QF 6 pounder (57 mm) gun (with 64 rounds of ammunition). It was used only for training. 1,059 produced.[citation needed]
A Centaur IV on the beach towing a 'Porpoise' sledge containing additional ammunition during the Normandy invasion. Porpoise was also used by the M7 Priest 105 mm howitzers.
Centaur II
Mark I with wider tracks and no hull machine gun. Experimental only.
Centaur III
Centaur armed with the 75 mm ROQF Mk V gun. In 1943, most Centaur I were converted to IIIs, but a few remained as such. 233 produced.[citation needed]
Centaur IV
Centaur armed with a 95 mm howitzer (with 51 rounds of ammunition). This is the only version of the Centaur known to have seen combat, in service with the Royal Marines Armoured Support Group. The vehicles were fitted with wading gear to get them ashore. Trunking waterproofed the engine inlets and covers were fitted to the guns. 114 produced.[11]
Centaur, AA Mk I
Used a Crusader III, Anti-Aircraft Mk II turret fitted with twin 20 mm Polsten guns. Were originally deployed in Normandy, but withdrawn as unnecessary due to Allied air superiority. 95 were produced.[citation needed]
Centaur, AA Mk II
Used a Crusader III, AA Mk III turret with twin 20 mm Polsten AA guns.
Cromwell I
Exactly the same as the Centaur I, but using the Meteor engine. Only 357 produced[citation needed] due to the switch from the 6 pounder (57 mm) to the 75 mm gun.
Cromwell
Cromwell II
Increased track width and removal of the hull machine gun to increase stowage. None produced.
Cromwell III
Centaur I upgraded with Meteor V12 engine. Only ~ 200 produced[citation needed] due to scarcity of Centaur I's.
Cromwell IV
Centaur I or III upgraded with Meteor engine, or built as such. The most numerous variant with over 1,935 units produced.[citation needed]
Cromwell IVw
Meteor engine, and all welded hull.
Cromwell Vw
Cromwell built from the start with the 75 mm gun and a welded instead of riveted hull.
Cromwell VI
Cromwell armed with 95 mm howitzer. 341 produced.[citation needed]
Cromwell VII
Cromwell IV and V upgraded with additional armour (101 mm to front), wider (15.5 inch) tracks, and additional gearbox. These were introduced very late in the war and did not see much in the way of combat. ~ 1,500 produced.[citation needed]
Cromwell VIIw
Cromwell Vw reworked to Cromwell VII standard, or built as new to that standard
Cromwell VIII
Cromwell VI reworked with same upgrades as VII.

Vehicles based on chassis[edit]

Centaur Dozer with hydraulic operated blade
Tank, Cruiser, Challenger (A30)
The design combined a lengthened Cromwell chassis with widened superstructure to mount the 17-pounder gun in a new turret.
SP 17pdr, A30 (Avenger)
A version of the Challenger using a lighter open-topped turret.
Centaur Dozer
A Centaur with the turret removed and given a simple dozer blade operated by a winch. Since the winch passed over the top of the hull it was not possible to retain the turret. One of "Hobart's Funnies". 250 produced.
Centaur Observation Post (OP)
A Centaur with a dummy main gun, and extra radio communications.
Centaur Kangaroo
A Centaur with turret removed to make space for passengers. (Few produced)
Centaur Armoured Recovery Vehicle (ARV)
A Centaur with turret removed, and replaced with winch fitted instead, and an optional A-frame.
Cromwell Command
The main gun was removed and it carried one No. 19 (Low Power) and one No. 19 (High Power) Wireless sets. These were used by brigade and divisional headquarters.[12]
Cromwell Observation Post
Cromwell IV, Cromwell VI, or Cromwell VIII fitted with extra radio equipment; 2 x No. 19 and 2 x No. 38 (portable) radios. The main gun was retained.[12]
Cromwell Control
Two No. 19 Low Power radio. Main armament kept. Used by regimental headquarters[12]
Excelsior tank
experimental design with elements of Infantry tank as a possible replacement for Churchill tank
FV 4101 Charioteer
Cromwell hull with a QF 20 pounder gun in a tall turret, designed in the 1950s to give more fire support 200 produced.

Surviving vehicles[edit]

Around 40 Centaur and Cromwell tanks survive, ranging from scrapyard wrecks to fully restored museum vehicles. At least two, one owned by the Czech Republic Army Technical Museum at Lešany and one owned by the Cobbaton Combat Collection in the United Kingdom, are in running condition.[13]

Other examples include:

  • Bovington Tank Museum, Dorset, England. Cromwell IV displayed in interior location accessible to public on payment of entry fee to museum.[14] and a Centaur dozer [15]
  • Thetford Forest, Norfolk, England. Cromwell IV in outside location freely accessible to public. This tank is located on the A1065 two miles north of Mundford. Between January and May 1944 the area was occupied by armoured regiments of the 7th Armoured Division (Desert Rats) prior to their embarking for Normandy. The tank forms part of a 1998 memorial to the Division. It is in good display condition having been refurbished and painted as a replica of the tank Little Audrey of 1st Royal Tank Regiment.[16]
  • The Royal Australian Armoured Corps Army Tank Museum, Puckapunyal, Victoria. Cromwell MkI shipped to Australia to assist with the up gunning of the Australian Cruiser tanks but did not arrive before that programme had been terminated. Repainted with the markings it arrived in Australia with, it is now under cover on display at the museum.
  • The Israeli Armored Corps Museum in Latrun. Cromwell IV tank, that was used by the IDF in War of Independence (1948–1949).
  • The Liberty Park in Overloon, The Netherlands. Cromwell IV tank, that remained on the battlefield after Operation Aintree during the Battle for Overloon in October 1944 in which the 11th Armoured Division was involved. This tank is on display in the museum, accessible to the public on payment of entry fee to museum.
  • The Tank Museum, Greek Army Armored Training Center, Avlona, near Athens, Greece. Centaur I (A27L) tank. The Greek Army received 52 Centaur I tanks from the British in 1946.
  • Centaur tanks have been discovered in a good state of preservation in the Solent, but are unlikely to be recovered.[17]
  • There is a remaining Cromwell tank at the A12 road leading into Antwerp Belgium.[citation needed]
  • There are two surviving Centaur IV CS in Normandy, at Benouville near Pegasus Bridge[18] and at La Brèche d’Hermanville[19]
  • There are two Portuguese Army's Cromwell tanks in Academia Militar (Portuguese Military Academy).

See also[edit]

Notes[edit]

Notes
  1. ^ The designation as the eighth Cruiser tank design, its name given for ease of reference and its General Staff specification number respectively
Citations
  1. ^ WWII Vehicles
  2. ^ a b "The A27M Cromwell tank". 
  3. ^ Fletcher The Great Tank Scandal p65-66
  4. ^ For their part, Rolls-Royce took over Rover's work on the British Whittle jet engines.
  5. ^ User Manual
  6. ^ Bingham p28
  7. ^ Bingham AFV Profile 25 p34-35
  8. ^ Fletcher, p 100
  9. ^ Bingham p30
  10. ^ Cromwell Tank p.xiii
  11. ^ Ness, Leland. Jane's World War Two Tanks and Fighting Vehicles. p. 22. 
  12. ^ a b c David Fletcher, Richard C. Harley, Peter Sarson. Cromwell Cruiser tank 1942–1950 (New Vanguard series). Osprey Publishing. p. 34. 
  13. ^ Pierre-Olivier (1 November 2010). "Surviving Cruiser Tanks". Surviving Panzers website. Retrieved 3 November 2010. 
  14. ^ "Cromwell IV (E1949.342)". The Tank Museum. 21 July 2009. Retrieved 2 October 2013. 
  15. ^ "Centaur Dozer Mark 1 (E1985.32)". The Tank Museum. Retrieved 2 October 2013. 
  16. ^ "Desert Rat Walk". Forestry Commission. Retrieved 8 November 2010. 
  17. ^ "Discovery in the Solent". FBBC. 28 July 2011. Retrieved 29 July 2011. 
  18. ^ "Benouville and St-Aubin-d'Arquenay". 1944 The Battle of Normandy The Memory. Normandie44lamemoire.com. Retrieved 2 October 2013. 
  19. ^ "Hermanville-s-M. and La Brèche d'Herm.". 1944 The Battle of Normandy The Memory. Normandie44lamemoire.com. Retrieved 2 October 2013. 

References[edit]

External links[edit]