Sorry still being dim (weapon systems I can fix, gearboxes are much more complicated!) /quote]Um thinks weapons systems, , ,OK Rick yes the torque converter allows g/box to not drive at tickover, think of central fugal force, at low tickover its [in ],rev it up it goes out [drive] so ya start moving, ems say i,m at this many revs ,this torque and this many mph,tell gearbox time ta shift to next gear but in between fluid drive ta slip to next gear ect, gearbox tell ems job done ,ready for next be it +or-, basic i know bit more than that but, because all this needs a good hydraulic oil function if say oil is low, or even degraded could degrade the slippin action or grippin action for a smooth auto box, so always check oil first,and best oh luck, , ,