page_title: Cromwell tank
section_title: Hull
hierarchical_section_title: Cromwell tank / Design / Hull
caption_attribution_description: English: Winston Churchill during the Second World War Winston Churchill inspects a Cromwell Mk IV tank of No. 2 Squadron, 2nd (Armoured Reconnaissance) Battalion, Welsh Guards, at Pickering in Yorkshire, 31 March 1944. The tank is named 'Blenheim'. The tank was the mount of Major John Ogilvie Spencer, commanding No. 2 Squadron, and later killed in Belgium on 9 September 1944.
context_page_description: The Cromwell tank, officially Tank, Cruiser, Mk VIII, Cromwell, was one of the series of cruiser tanks fielded by Britain in the Second World War. Named after the English Civil War leader Oliver Cromwell, the Cromwell was the first tank put into service by the British to combine high speed from a powerful and reliable engine, and reasonable armour. The intended dual-purpose high velocity gun could not be fitted in the turret and the medium velocity dual purpose gun fitted proved inadequate. An improved version with a high velocity gun became the Comet tank.
  The name "Cromwell" was initially applied to three vehicles during development. Early Cromwell development led to the creation of the A24 Cavalier. Later Cromwell development led to the creation of the competing Tank, Cruiser, Mk VIII, Centaur design. The Centaur tank was closely related to the Cromwell, both vehicles being externally similar. The Cromwell and Centaur tanks differed in the engine used; the Centaur had the 410 hp Liberty engine, the Cromwell had the significantly more powerful 600 hp Meteor.
  The Cromwell first saw action in the Battle of Normandy in June 1944.
context_section_description: 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.
  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. Some variants were produced with 14-inch-wide (360 mm) tracks; later, 15.5-inch tracks were used. 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, known as the "slack-track" design. 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 transmission was the new Merrit-Brown Z.5, which offered differential steering without clutching or braking, a major advance on previous designs. It gave the Cromwell superb manoeuvrability, with only the German Tiger I, using a similar design, able to match it.
  The Meteor engine delivered 540 hp at 2,250 rpm giving the Cromwell speed as well as manoeuvrability. 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, with the hull gunner on the left, separated 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 to cover the lowermost air outlet. Air for the engine could be drawn from the fighting compartment or the exterior; it was then passed through oil bath cleaners. It was modified so that the exhaust fumes were redirected so that they were not drawn into the fighting compartment, a problem found when tanks were drawn up together, preparing to advance.
  In June 1944, the Cromwell saw action during Operation Overlord, the Allied invasion of Normandy. It had a mixed reception by crews, being faster, with a lower profile and thicker frontal armour plate than the Sherman tank, but also being smaller and more cramped. Cromwell had 3 in (76 mm) of frontal armour compared with 2 in (51 mm) on the glacis of the early Shermans, though it was unsloped and hence less effective in head-on combat. On later Cromwells this was further increased, first to 3 ¹⁄₄ in (83 mm), then to 4 in (100 mm).
caption: Churchill inspecting a Cromwell. The driver can be seen looking through the port to the left, with periscopes above him.
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