The fast moving, penetrating thrusts of German Panzer armies proved as successful invading Russia in 1941 as in France in 1940. But the new Russian tanks, about which the Germans knew nothing, came as a nasty shock. The new cruiser T34 and heavy KVl tanks were the most heavily armed and probably the finest machines in their class in the world. Poor Soviet tactical deployment of their armour caused the crushing defeats in 1941. With high fire power and mobility and well-sloped armour, the T34 was an excellent design. It remained the standard battle tank of the Soviet army throughout the war. The Russians had a range of rugged reliable diesel engines which culminated in the large Kharkiv model V-2 engine used in both the T34 and KVl. With a weight of 30 tons the tank had a very high power-weight ratio which. A ground pressure of only ten psi, gave outstanding cross-country performance. Christie-type suspension – each of wheels independently sprung on coil springs inside the hull – enabled the tanks to be used over most ground. To lower costs and speed production the finish was crude in places where this mattered least. During the winter of 1943-44 the T34/76 was replaced by the T34/85, issued first to the elite Guards regiments which had an 85-mm gun (a version of the MI939 anti-aircraft gun) and a performance equivalent to the German 8·8-cm in Tiger I. The new gun was mounted in a larger, three-man, cast turret, and the crew was increased from four to five. With this tank the Russians achieved a tremendous increase in fire power with only a small increase in weight and effect on manoeuvrability. Although not as good as the German Panther it was better than anything the British or Americans had.