However, with over 50 metric tons dead weight, suspensions, gearboxes and other such items had clearly reached their design limits and breakdowns were frequent. Design studies for a new heavy tank had been started in 1937, without any production planning. Renewed impetus for the Tiger was provided by the quality of the Soviet T-34 encountered in 1941.[29] Although the general design and layout were broadly similar to the previous medium tank, the Panzer IV, the Tiger weighed more than twice as much.