Unit for controlling the shaft for selection and engagement of the gears of a gear change

Unit (1) for controlling a shaft (2) for selection and engagement of gears of a gear change (3), wherein the shaft (2) for selection and engagement of the gears is mobile, after axial displacements and/or rotations have taken place, between a plurality of gear engagement positions, to each of which there corresponds engagement of a gear or of a neutral position;

• the positions of engagement of the gear being disposed according to a selection grid in the shape of an “H” in which the gears are distributed in rows of two;
• the control unit (1) comprising:
• an outer housing (5);
• a control shaft (6) which is fitted on the said housing (5), such as to be able to rotate angularly around its own axis (A), in order to implement a maneuver of engagement or release of the gears, and is axially mobile along its own axis (A), in order to implement a maneuver of selection of a row of gears;
• for each row of gears the said control shaft (6) also being able to assume three different angular positions, corresponding respectively to a neutral angular position and two angular positions for engagement of the gear;
• movement means (7), which are designed to displace the said control shaft (6) angularly around its own longitudinal axis (A), between the said three different angular positions;
• and
• cam guide means (8), which are connected mechanically to the said control shaft (6), and which, during the angular displacement of the control shaft (6) which implements the passage between the two angular positions of engagement of gears in a row, are designed to impart selectively to the control shaft (6) itself axial displacement which is sufficient to implement passage to the row which is immediately adjacent, such as to implement the passage between consecutive gears which belong to consecutive rows;
• the control unit (1) being characterised in that the said cam guide means (8) are axially mobile along the control shaft (6), between a plurality of row-change positions, at each of which it can guide the control shaft (6) in combined angular and axial displacement, which is sufficient to transform the passage of gear between two gears which belong to a single row, into a passage of gear between two consecutive gears which belong to two consecutive rows.