By the summer of 1938 it was determined that the proposed A-20 might be insufficiently armed and armoured for the medium tank role. The Red Army therefore decided it would need another proposed medium tank design that would be designated the A-32 and have a maximum armour thickness on the front of the turret of 32mm. It would be armed with a short-barrelled 76.2mm main gun.
By May 1939 it was decided to thicken the maximum armour on the front of the A-32 turret to 45mm. This up-armoured version of the vehicle was designated the A-34 in the summer of 1939. In August 1939 the Red Army decided to adopt the A-34; a decision concurred with by Joseph Stalin, the leader of the Soviet Union, in December 1939. The first A-34 prototype appeared in January 1940, with the second prototype rolling off the factory floor the following month.
To prove the reliability of the A-34 prototype tanks before submitting them for the final approval of the Red Army, a demonstration run that would encompass a distance of 1,800 miles (2,897km) during the winter months of February and March 1940 was arranged. On 17 March 1940, the two A-34 prototypes arrived in Moscow for a personal inspection by Stalin and other high-ranking members of the government and military élite. Despite the misgivings by some that the A-34 was not yet suitable for production, Stalin gave his blessing to the production of the vehicle once any design faults uncovered during testing by the Red Army were addressed.
Additional testing of the A-34 prototypes led to the conclusion that the vehicle was superior to any other tank then in Red Army service, and by the end of March 1940 the tank was approved for production as the T-34. Besides a short-barrelled 76.2mm main gun, the T-34 would also be armed with a coaxial 7.62mm machine gun and another 7.62mm machine gun in the front hull. The first 150 units of the T-34 also featured a 7.62mm machine gun in a ball mount in the rear of the turret.
Despite production of the four-man T-34 being approved, there were still some hurdles that had to be overcome. One of the original requirements called for the vehicle to operate over 1,864 miles (3,000km) without a major breakdown. A mileage test done in April 1940 showed that the tank could not meet this requirement. However, this was soon dropped to 621 miles (1,000km). The Red Army went ahead and placed an order with two factories for 600 T-34s to be built starting in June 1940. They also placed a production order for 2,800 units of the T-34 for 1941. The heavy tank design bureau In Leningrad had reversed many years of Soviet practice by naming their new tank the Klimenti Voroshilov, or KV after the egregious Defence Commissar. With some courage, Koshkin told Voroshilov that the new tank should not be named after another hero of the Soviet Union; rather they should return to using the traditional designations. Koshkin suggested the designation T-34 to commemorate the 1934 state decree which ordered a massive expansion of the Soviet armoured forces. It was also the year that Koshkin had had his first ideas about the new tank. Accordingly, Koshkin’s proposal was accepted.
Once the team received official sanction to build a purely tracked medium tank, they had returned to their original design for the A-32. The T-34 required thicker armour, but it also needed to be equipped with more firepower as well as a reliable transmission. Morozov and the transmission group devoted considerable time and effort to finding a solution to these problems.
The two prototypes were ready by January 1940, and Koshkin took them on a gruelling trial march to prove the hardiness of the design. He drove them from Kharkov to Moscow, and here the tank was presented to the Red Army. Following this presentation, they were sent on to Finland for combat tests against the Mannerheim Line, but unfortunately they arrived too late to see any action. However, Koshkin and his team were able to demonstrate the power of the T-34’s armament against captured Finnish bunkers. There were further firing trials in Minsk, and then it was on to Kiev, and finally back to Kharkov. This round trip had covered a distance of 2880km (1800 miles) in the bitter weather of February and March.
During June the drawings were completed and mass production began. The first production T-34 Model 1940 rolled out of Kharkov in September 1940. During the gruelling winter test-drive, Koshkin had contracted pneumonia, and he died on 26 September 1940. Morozov, now head of conceptual design, took over the T-34 project.
SUMMARY OF ALL T-34 VARIANTS
As the T-34 was produced from different factories, models and types varied. In August 1939, the Soviet Main Military Council accepted the T-34 as the Red Army’s medium battle tank. The new design was completed during December 1939 and became known as the T-34 (Model 1940). On 19 December 1939, the drawings and models of the new T-34 were submitted to the High Command, which accepted them for production, even though the prototype had not yet been completed.
THE CHASSIS AND SUSPENSION
The chassis, based on the Christie system, had five pairs of large road wheels with a gap between the second and third. Each wheel’s suspension was independently mounted, and transversely swung on a vertical coil spring inside the hull. The drive sprocket was mounted at the rear to reduce vulnerability. It was the same roller type used on the BTs. The drive sprockets drove wide, 483mm (19in) skeleton-type cast-manganese steel tracks with centre guide horns positioned on alternate track links.
The system had an interesting and ingenious method of retaining its track pins. The roundhead pins were inserted from the inside; there was no retaining device used on the track itself. Instead, a curved wiper plate was welded to each side of the hull at the rear, level with the top run of the track. Therefore, any loose track pin passing the wiper plate in motion was immediately knocked back into place. The method also allowed the rapid removal and replacement of track blocks, considerably easing and speeding up maintenance and repairs in the field. The wide tracks provided a small specific ground pressure not exceeding 0.7-0.75kg per cm (10-10.6Ib per in), while that of British, German and American medium and heavy tanks was 0.95-lkg per cm (13.1-13.9Ib per in). Track guards covered the top of the suspension system and extended 25cm(9.8in) beyond the hull at the front and 10cm (3. 9in) at the rear. The suspension permitted the T-34 to retain high speeds even when moving over rough terrain, while the wide tracks on the tank, weighing only 28.3 tonnes (28 tons), meant that it could traverse muddy terrain, as well as snow-covered ground.
The first production-line models were fitted with V-2 diesel engines, but shortages meant that some of these early models were equipped with the older M-17 petrol engine. Problems with transmissions were such that the T-34/76 (Model 40) often went into battle with spare transmission units secured to the engine compartment deck by steel cables.
The Model 40 had a rolled plate turret and a short 76.2mm (3in) L/30.3 (L-11) Model 1938 tank gun mounted in a distinctive cast cradle welded to a flush outside mantle. The Model 40 established a standardization pattern among the T-34 variants of having a great number of interchangeable parts, such as engine, armament, transmission and periscopes. Mechanical simplicity was a prime concern. The hull was of a welded construction throughout, with only three different thickness of rolled plate armour.
The Christie suspension had five large, double road wheels on each side, with a noticeably larger gap between the second and third wheels. The drive sprocket, located for safety to the rear, was of the roller type used on the BT series and powered a cast manganese-steel track with centre guide horns on alternative track links. This first model of the T-34 had a distinctive turret overhang and a clumsy turret hatch occupying the entire rear part of the turret. The Model 40 had one periscope fitted on the front lefthand side. In late 1941, a small number were fitted with the long-barrelled, high velocity 57mm (2.24in) ZiS-4 gun, to engage light armoured vehicles at greater ranges than the 76.2mm (0.303in) L-ll.
The first production unit of the Red Army’s new 58,912-lb (29mt) medium tank rolled off the production line in September 1940. This vehicle is now commonly referred to as the T-34 Model 1940. By the time the German army invaded the Soviet Union in June 1941, 1,225 units of the T-34 Model 1940 were in service, of which 967 had been delivered to field units. Maximum armour thickness on the front of the vehicle’s turret was 45mm.
Initial German army encounters with the T-34 Model 1940 raised a great deal of alarm among both their infantry and armour branches. Their existing anti-tank weapons proved unable to penetrate the thick, well-sloped armour on the T-34, and the vehicle’s 76.2mm main gun easily penetrated the armour on the German Panzer III and Panzer IV medium tanks it encountered. This would eventually lead to the up-gunning and up-armouring of the existing German medium tanks, and the development of the German Panther medium tank series and Tiger E heavy tank as a counter to the T-34.
The Red Army early war battlefield technical superiority in medium tanks was offset by the fact that the T-34 Model 1940 was just entering service and their crews often had little training in the use of their new tanks. Compounding the problem was the fact that most of the tanks did not have radios. There were also shortages of everything from main gun ammunition to fuel and spare parts for the T-34-equipped units confronting the Germans, and these factors allowed their army to easily prevail over the Red Army during the early phase of their invasion of the Soviet Union.
The 76.2mm main gun initially selected for use by the Red Army on the T-34 Model 1940 was designated the L-11. It was not the desired weapon in the opinion of the vehicle’s designers due to its relatively low muzzle velocity and hence poor armour penetration ability. Due to almost everybody’s unhappiness with the L-11, other weapons were considered for the T-34 Model 1940, including the ZiS-4 57mm anti-tank gun. A few of these were actually mounted in the vehicle to test their effectiveness.