Christie suspension The Christie suspension is a suspension system developed by American engineer J . Walter Christie for his tank designs . It allowed considerably longer movement than conventional leaf spring systems then in common use , which allowed his tanks to have considerably greater cross - country speed . The system was first introduced on his M1928 design , and used on all of his designs until his death in 1944 . History . Christie advocated the use of lightweight tanks with long range and high speed , designed to penetrate enemy lines and attack their infrastructure and logistics capabilities . His earlier designs in the 1920s were hampered by poor cross - country performance due to limited suspension capability . In the late 1920s he devised a better solution . The major problem he faced was the limited vertical space for springs to move in : for a 25 cm movement it might need 50 or 75 cm of vertical space for the spring and strut , and his small designs did not offer such space . The solution was the addition of a bellcrank , which changed the direction of motion from vertical to horizontal . The road wheels were individually mounted on a pipe that could move vertically only , at the top of which the bell crank rotated the direction of motion to the rear . Springs were mounted on the end of the crank , and could be as long as needed , lying along the inside of the hull . The result was a substantial increase in range of motion , from only some 10 cm in his original designs , to 25 cm on the M1928 , 35 cm on the M1930 , and 60 cm on the M1932 . The most famous Christie - based tanks , the Soviet BT tank series and the T - 34 , used coil springs mounted vertically ( on the BT ) or at a slight angle from vertical ( the T - 34 ) . Another feature of Christie ' s designs was the " convertible " drive : the ability to remove the tracks for road travel , allowing for higher speeds and better range , and reducing wear on the fragile caterpillar track systems of the 1930s . In one public test 1931 in Linden , NJ , Army officials clocked a Christie tank going 104 mph , making it the fastest tank in the world : A record many believe it still holds . To allow this , Christie used large rubber - rimmed road wheels , with no return rollers for the tracks , although wartime shortages often led to the use of steel wheels , which gave an uncomfortable ride . As with many track designs with center guide teeth , dual wheels were used , allowing the guide teeth to run between them . By 1939 , the Soviets found that the BT tank ' s convertible drive was an unnecessary complication which occupied valuable space in the tank , and the feature was dropped in the T - 34 . Because large road wheels and " slack track " are characteristic of the Christie suspension , other designs with these features are sometimes misidentified as such . The real Christie suspension was used only on a few designs , notably the Soviet BT tank s and T - 34 , the British Cruiser tank s , including the A13 ' s : Cruiser Mk III , Cruiser Mk IV , Covenanter , Crusader , Cromwell and the Comet , as well as some experimental Polish and Italian designs and the modern day Israeli Merkava tank s .