Shift control device of vehicular transmission

A shift interlock between a primary transmission having an input shaft, an output shaft and first shifting means for controlling the rotational relationship between said input shaft and said output shaft, said first shifting means comprising a first shifting drum supported for rotation about a first axis and means responsive to the rotation of said first shifting drum for changing the rotational relationship between said input shaft and said output shaft, an auxiliary transmission having an input shaft driven by said primary transmission output shaft and an output shaft and second shifting means for controlling the rotational relationship between said input shaft and said output shaft of said auxiliary transmission, said second shifting means comprising a second shifting drum supported for rotation about a second axis and means responsive to the rotation of said second shifting drum for changing the rotational relationship between said input shaft and said output shaft of said auxiliary transmission, said interlock comprising a link pivotally connected at one end to one of said shifting drums at a position offset from the rotational axis of said one shifting drum, means for retaining the movement of the other end of said link in a generally reciprocating fashion adjacent the other of said shifting drums, and cam means on said other shifting drum for precluding rotation of said other shifting drum when said link end is in a position for establishing a certain rotational relationship between the input and output shafts of its associated transmission.