to down-shift ("kick down") to a lower gear when the Throttle Valve is in the full stop position (throttle pedal is fully depressed) and road speed is below a set point regulated by a mechanical governor on the output shaft. The hydraulic control system consists of a valve arrangement and an engine driven pump. The automatic transmission contains a planetary gear set consisting of two sun gears, two sets of three planet pinions contained within a planetary carrier and ring gear. Various speed ratios are obtained by holding or clutching various combinations of elements of the planetary train. This is performed by two bands, two multi-disc clutches and a one-way clutch. When the transmission of the motionless vehicle is placed in Drive, the transmission allows the vehicle to move off in first gear, then will change to second and then to third gear based on an increase in road speed. The BW-35 will downshift from third to second and from second to first, also based on load. The transmission is equipped to produce kickdown and will upshift after kickdown if accelerator pressure is released following a kickdown. The Borg Warner 35 was designed for use with Type F Automatic Transmission Fluid (ATF), which is far less common today than the Mercon/Dexron type. Users Initially produced in the U.S. in the 1950s specifically for engines of less than 200 cubic inches engine displacement and less than (American Motors Rambler and Studebaker mainly). Prior and contemporary automatic transmissions were very inefficient and would work best with larger, more powerful engines, and even when used in those applications, the engines would often have higher compression ratios and more power than the manual transmission versions. Prior automatic transmissions were used with the small sixes in the US in the late 50s and early 60s, but the heavy internal components of the early automatics were detrimental to economy, the main reason a lighter automatic transmission was developed. In addition, lower differential ratios differentials were usually used in other automatic transmission applications to improve gas mileage (again due to the inefficiency of the earlier automatics, especially when used with small engines). The BW 35 was a more efficient transmission and was quite successful in the US with the smaller engined cars. This also made it a natural for European cars that usually had much smaller engines than American cars of that era. Production was transferred in