The present invention relates to a shift mechanism for a change-speed gear transmission for use in automotive vehicles, and more particularly to a shift mechanism of the type which comprises a manual gearshift lever arranged to be selectively shiftable toward forward speed-ratio and reverse-ratio positions at the same gate in a gearshift pattern, a selector shaft mounted within a housing assembly of the gear transmission for both axial and rotary movement and being operatively connected to the gearshift lever to be axially moved in selecting operation of the gearshift lever toward the gate and to be rotated in shifting operation of the gearshift lever toward one of the forward speed-ratio and reverse-ratio positions, and a movable member mounted on the selector shaft for axial and rotary movement integral with the selector shaft and having a radial lever arm arranged to be selectively movable for establishing a forward speed-ratio gear train in shifting operation of the gearshift lever toward the forward speed-ratio position and for establishing a reverse-ratio gear train in shifting operation of the gearshift lever toward the reverse-ratio position.
In such a shift mechanism as described above, it is afraid that the gearshift lever is erroneously shifted from its forward speed-ratio position to its reverse-ratio position across the same gate in the gearshift pattern. It is, therefore, required to prevent such an error in shifting operation of the gearshift lever toward the reverse-ratio position.