Medium Mark III
Encyclopedia
The Medium Mark III was a medium tank developed in the United Kingdom
during the inter-war period. The tank was unsuccessful with only 3 built. The design did not directly derive from earlier Medium Mark II tank.
The War Office
added some extra requirements: a separate engine compartment; superior steering capacity and 13 millimetres frontal armour with 9 millimetres thickness for the other plates.
In September Vickers, given the order to build a prototype, proposed a first design based on the Vickers A1E1 Independent
, with the fighting compartment in front and the engine compartment at the back. There would be a central two-man turret with a 3-pounder (47 mm) gun
and a coaxial machine-gun; it was intended to house the commander and a special observer, each being provided a separate cupola. In the front of the hull were to be placed two secondary machine-gun turrets, each with a twin Vickers machine gun
. At the back of the vehicle, behind the main turret a third machine-gun turret was intended, armed with an anti-aircraft (AA) weapon. A crew was needed of seven men. Maximum armour would be 13 millimetres and basis armour 6.5 millimetres, limiting the weight to fourteen tons. Riveted plates were used. The total fuel supply would be 120 Impgal gallons: ten in a small tank inside, gravity feeding the engine; the remainder in external tanks on the fenders. Two engine options were indicated: a 120 hp engine would allow for a speed of 14 mph and a 180 hp engine would raise this to 20 mph (32.2 km/h).
The result was called A6. In March 1927 a wooden mock-up was presented and after approval a second and prototype were ordered which had to incorporate the new hydraulically operated Wilson epicyclic steering gearbox, the predecessor of the Merrit-Brown gearbox. By June 1928 both prototypes (A6E1 and A6E2) were presented to the Mechanised Warfare Experimental Establishment for trials. Vickers was on this occasion ordered to add armour skirts but keep within the weight limit by removing armour elsewhere. Meanwhile a third prototype had been ordered: A6E3.
A6E1 and A6E3 were fitted with a Armstrong Siddeley air-cooled V8 180 hp engine giving a maximum speed of 26 mph; A6E2 however, originally with the Ricardo
CI 180 hp engine. Later A6E3 was re-engined with the Thornycroft 6V 500 hp. It was proposed to combine two Rolls-Royce Phantom
engines with the Wilson transmission system on the A6E1, but in view of the costs this was rejected. A6E2 was eventually refitted with the AS V8 180 hp.
The guns were tested in July 1928. This proved that the twin-machine gun arrangement was unworkable; the A6E3, then being constructed, therefore was fitted with a simplified design with a single machine-gun; it also had single cupola on the centreline of the turret. The AA-turret was removed from A6E1. However it was also shown that the suspension and the gunnery arrangements were distinctly inferior to those of the Mark II. It was therefore decided to discontinue the development of the type and use the three vehicles merely as test-beds for the automotive parts. In 1929 Vickers submitted three alternative suspension designs, which were fitted to the respective prototypes; one of these, tried on A6E3, involved a fundamental reconstruction of the hull. None proved able to provide a stable gun platform. Only in 1934 a satisfactory type was fitted by a specialised firm.
and a bulge at the back to hold the radio set. The secondary machine-gun turrets were moved more to the front to shift the centre of gravity of the entire vehicle forward to improve its stability. Larger brakes were fitted. In 1933 trials were completed of the first two prototypes. The type was reliable and provided a good gun platform. However, it still suffered from its bad suspension design: even though road speed increased to thirty miles per hour, during cross-country rides the bogies were often overloaded. Three Mark IIIs were built, one by Vickers and two by the Royal Ordnance Factory
at Woolwich: Medium III E1, E2 and E3. The third had an improved suspension and the vehicles were in 1934 taken into use by the HQ of the Tank Brigade. However, no orders followed due to its high price; Medium III E2 was lost to a fire.
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
during the inter-war period. The tank was unsuccessful with only 3 built. The design did not directly derive from earlier Medium Mark II tank.
A6 "Sixteen tonners"
In 1926, the British War Office wanted to replace their existing Mark II tanks with a new design. In May the Royal Tank Corps Centre was asked for its opinion, which it submitted in July. One of the requirements was a weight limit of 15.5 tons, which led to the nickname "16-tonners". Other specifications included that it could transported by rail; a sufficient supply of lubrication oil to match the range of the tank (dictated by the fuel carried); a wireless set; a gun capable of defeating enemy armour at a range of at least a thousand yards; fuel tanks external to the main compartments and bottom armour sufficient to withstand heavy machine-gun fire when exposed while climbing a crest. Furthermore the machine should be as silent as possible, as with previous types the engine noise tended to incapacitate the crew.The War Office
War Office
The War Office was a department of the British Government, responsible for the administration of the British Army between the 17th century and 1964, when its functions were transferred to the Ministry of Defence...
added some extra requirements: a separate engine compartment; superior steering capacity and 13 millimetres frontal armour with 9 millimetres thickness for the other plates.
In September Vickers, given the order to build a prototype, proposed a first design based on the Vickers A1E1 Independent
Vickers A1E1 Independent
The Independent A1E1 is a multi-turreted tank that was designed by the British armaments manufacturer Vickers during the interwar period. Although it only ever reached the prototype stage it influenced many other tank designs....
, with the fighting compartment in front and the engine compartment at the back. There would be a central two-man turret with a 3-pounder (47 mm) gun
OQF 3 pounder gun
The Ordnance QF 3 pounder gun was a British tank gun mounted on Vickers Medium Tanks in the 1920s and 1930s. The gun was produced in 32 calibre and 40 calibre versions.-References:* Anthony G Williams,...
and a coaxial machine-gun; it was intended to house the commander and a special observer, each being provided a separate cupola. In the front of the hull were to be placed two secondary machine-gun turrets, each with a twin Vickers machine gun
Vickers machine gun
Not to be confused with the Vickers light machine gunThe Vickers machine gun or Vickers gun is a name primarily used to refer to the water-cooled .303 inch machine gun produced by Vickers Limited, originally for the British Army...
. At the back of the vehicle, behind the main turret a third machine-gun turret was intended, armed with an anti-aircraft (AA) weapon. A crew was needed of seven men. Maximum armour would be 13 millimetres and basis armour 6.5 millimetres, limiting the weight to fourteen tons. Riveted plates were used. The total fuel supply would be 120 Impgal gallons: ten in a small tank inside, gravity feeding the engine; the remainder in external tanks on the fenders. Two engine options were indicated: a 120 hp engine would allow for a speed of 14 mph and a 180 hp engine would raise this to 20 mph (32.2 km/h).
The result was called A6. In March 1927 a wooden mock-up was presented and after approval a second and prototype were ordered which had to incorporate the new hydraulically operated Wilson epicyclic steering gearbox, the predecessor of the Merrit-Brown gearbox. By June 1928 both prototypes (A6E1 and A6E2) were presented to the Mechanised Warfare Experimental Establishment for trials. Vickers was on this occasion ordered to add armour skirts but keep within the weight limit by removing armour elsewhere. Meanwhile a third prototype had been ordered: A6E3.
A6E1 and A6E3 were fitted with a Armstrong Siddeley air-cooled V8 180 hp engine giving a maximum speed of 26 mph; A6E2 however, originally with the Ricardo
Ricardo plc
Ricardo plc is a British publicly listed company named after its founder, Sir Harry Ricardo and founded on 30 June 1927 in Shoreham-by-Sea, West Sussex. The company is a leading global multi-industry engineering provider of technology, product innovation and strategic consulting...
CI 180 hp engine. Later A6E3 was re-engined with the Thornycroft 6V 500 hp. It was proposed to combine two Rolls-Royce Phantom
Rolls-Royce Phantom
Rolls-Royce has used the Phantom name on luxury cars over the past century:* Rolls-Royce Phantom I, 1925–1931* Rolls-Royce Phantom II, 1929–1936* Rolls-Royce Phantom III, 1936–1939* Rolls-Royce Phantom IV, 1950–1959...
engines with the Wilson transmission system on the A6E1, but in view of the costs this was rejected. A6E2 was eventually refitted with the AS V8 180 hp.
The guns were tested in July 1928. This proved that the twin-machine gun arrangement was unworkable; the A6E3, then being constructed, therefore was fitted with a simplified design with a single machine-gun; it also had single cupola on the centreline of the turret. The AA-turret was removed from A6E1. However it was also shown that the suspension and the gunnery arrangements were distinctly inferior to those of the Mark II. It was therefore decided to discontinue the development of the type and use the three vehicles merely as test-beds for the automotive parts. In 1929 Vickers submitted three alternative suspension designs, which were fitted to the respective prototypes; one of these, tried on A6E3, involved a fundamental reconstruction of the hull. None proved able to provide a stable gun platform. Only in 1934 a satisfactory type was fitted by a specialised firm.
Medium Mark III
The disappointments in the A6 design led to a new design, the "Medium Mark III", being ordered in 1928 and constructed from 1930. It was similar to the A6 design but featured a new turret and improved armour. The turret had a flat gun mantletGun mantlet
A gun mantlet is an armour plate or shield attached to an armoured fighting vehicle's gun, protecting the opening through which the weapon's barrel projects from the hull or turret armour and, in many cases, ensuring the vulnerable warhead of a loaded shell does not protrude past the vehicle's...
and a bulge at the back to hold the radio set. The secondary machine-gun turrets were moved more to the front to shift the centre of gravity of the entire vehicle forward to improve its stability. Larger brakes were fitted. In 1933 trials were completed of the first two prototypes. The type was reliable and provided a good gun platform. However, it still suffered from its bad suspension design: even though road speed increased to thirty miles per hour, during cross-country rides the bogies were often overloaded. Three Mark IIIs were built, one by Vickers and two by the Royal Ordnance Factory
Royal Ordnance Factory
Royal Ordnance Factories was the collective name of the UK government's munitions factories in and after World War II. Until privatisation in 1987 they were the responsibility of the Ministry of Supply and later the Ministry of Defence....
at Woolwich: Medium III E1, E2 and E3. The third had an improved suspension and the vehicles were in 1934 taken into use by the HQ of the Tank Brigade. However, no orders followed due to its high price; Medium III E2 was lost to a fire.