BT is the abbreviation of the Russian term for “fast tank”, with the BT-7 being the last in a line of Soviet fast tanks designed during the 1930’s. Each tank in the series incorporated the Christie type suspension – as designed by J. Walter Christie. The BT series of tanks where also know as convertibles in that they could be driven either on tracks or on their road wheels, carrying their tracks with them. The rear set of road wheels where powered while the front set was steerable. In practical term, however, the removal and replacing of the tracks proved to be a laborious and time-consuming process, thus this option was often ignored by its crews.
