impeller 21 connected with the shaft 2 a turbine runner 22 a stator 23 and a lock up clutch 24 the auxiliary transmission unit 40 comprises a planetary gear mechanism having a carrier 41 also serving as an input rotational member of the auxiliary transmission unit planetary pinions 42 only one is shown a sun gear 43 and a ring gear 44 also serving as an output rotational member of the auxiliary transmission unit a clutch c0 for selectively connecting the carrier 41 with the sun gear 43 a brake b0 for selectively braking rotation of the sun gear 43 from the housing hu of the transmission and a one way clutch f0 for connecting the sun gear 43 to the carrier 41 only when the carrier 41 would rotate relative to the sun gear 43 in the normal rotational direction the main transmission unit 60 comprises a first planetary gear mechanism having a sun gear 61 a ring rear 62 planetary pinions 64 only one is shown and a carrier 66 a second planetary gear mechanism having a sun gear common with the sun gear 61 a ring gear 63 connected with the carrier 66 of the first planetary gear mechanism planetary pinions 65 only one is shown and a carrier 67 a clutch c1 having an outside rotational member serving as an input rotational member of the main transmission unit and selectively connecting the ring gear 62 of the first planetary gear mechanism with the.