The Soviet T-34 Medium Tank became one of the most successful tank designs in the history of armored warfare after it debuted in the fighting of World War 2 (1939-1945). Its sheer availability and inherent versatility made it a good candidate for experimental designs and offshoots based on the proven framework for a slew of variants followed. One of the more important additions to the line became the "T-34/85" (detailed elsewhere on this site) which successfully mated the existing tank to a more effective 85mm main gun. When even this weapon showed its limitations on the battlefield, particularly against the newer, heavier German tanks like the Panther and Tiger series, thought was given to another up-gunned form - this becoming the "T-34/100".
NOTE: This T-34/100 should not be confused with the Egyptian T-100 tank destroyer development, which was also later known as the T-34/100.
Tangible work on what was to become the T-34/100 began in the middle of 1944 by Factory No.183 (Nishni Tagil) and involved considerable study and testing of several larger-caliber weapons available to the Soviets. Such a powerful weapon would need a strong chassis, hull, and turret design and the turret would have to feature an enlarged ring due to the greater dimensions at play. In the early-going, the focus weapon of the project became the ZiS-S-53 (ZiS-100) gun simply mated to the existing turret of the T-34/85 tank.
Testing showed this coupling to be ineffective for the weapon required much of the tank's under-workings when fired due to inherently violent recoil forces and excessive weight. Thought now switched to the in-development turret of the soon-to-be "T-44" Medium Tank (detailed elsewhere on this site) and this turret would sit atop the existing hull of the T-34/85. Due to the turning radius of this turret, the T-34/85's hull was appropriately modified to seat it.
This particular evolution also involved various changes to the original T-34/85 offering - armor protection, particularly at the floor and engine compartment, were reduced to compensate for the added weight and required space of the new turret which weakened the tank's protection some. For the same reasons, the suspension system and related drive components were all reinforced.
Testing of this system occurred from February to March of 1945 even as the Soviet Army made great strides against the German defenses en route to Berlin itself. Alongside the ZiS-100 weapon the D-10T (100mm D-10-34) anti-tank gun was also trialed (this the same weapon as found on the SU-100 Tank Destroyer) - but this, too, proved an unfavorable mating. By the time of April 1945, the focus became the LB-1 as a main gun and, with its accompanying recoil mechanism, finally proved a 100mm-armed T-34 a sound investment.
The outward appearance of this finalized tank was very reminiscent of the T-34 with its heavily angled, sloping armor facings. The turret was positioned forward of midships with the engine at the back of the hull. Armor protection spanned 20mm to 90mm at the various facings. The 100mm-armed turret offered considerable overhang of the main gun barrel over the bow and anti-infantry measures included 2 x 7.62mm DT machine guns, one fitted coaxially alongside the main gun and another in a bow-mounting with limited traversal/elevation. A commander's cupola was featured at the turret roof for improved situational awareness.
Dimensions included a running length of 9.2 meters with the gun forwards, a beam of 3 meters and a height of about 2.5 meters. Combat weight reached 33 tonnes.
The running gear involved five large road wheels to a hull side with no track-return rollers used. Power was from a single W-2-34 12-cylinder diesel-fueled engine of 500 horsepower. Road speeds could reach 48 kmh and operational range was estimated at 300 km when traveling about roads.
Despite the work already put into the T-34/100, its late-war arrival meant that the design was never put into serial production. The end of the war in Europe in May of 1945 signified the end of the T-34/100 initiative and its attempt to succeed the classic T-34. The 85mm-armed T-44, introduced in 1943, also failed to succeed the famous design and only 1,823 were built though none saw action in World War 2. The T-34/85 would take the T-34 mantle for the foreseeable future and continued in service for decades more.