Attempt to give a medium tank a Christie suspension, T-29 was developed from 1934 to 1936 in Leningrad. The speed T-29 was able to reach were satisfactory, but the tank was not put into serial production, because despite it's speed and relative armor, the production was more costly while having the same results as cheaper BT tanks.
T-29 was capable to demount the tracks and use the wheels just as BT tanks, moving in high speeds on roads, but in terrain it would cause damage to the suspension. Armed with 76mm gun, T-29 would have been a decent tank design if accepted into production.