Gear change control system of automatic transmission

A gear change control system of an automatic transmission, comprising:

• a shift member, including a shaft portion disposed in such a manner that a selection axis thereof is oriented in a selecting direction, and including an arm portion formed on the shaft portion in such a manner as to project therefrom;
• and
• a plurality of shift rail members, having rail shaft portions, and arranged in such a manner that shift axes of the rail shaft portions are oriented in a shifting direction, shift fork portions formed on the rail shaft portions in such a manner to project therefrom and operable to make gear shifts of gears within a change-speed gear section, shift lug members being formed on the rail shaft portions in such a manner to project therefrom and being capable of facing the arm portion, wherein the arm portion of the shift member moves for selection and gear shifting and presses against a selected shift lug member, so that a gear shift to a target gear is attained by the shift fork portion linked with the shift lug member so pressed against via the rail shaft portion,
• wherein, the shift lug members include pillar-shaped portions projecting substantially vertically from the shift rail members in a side view of the shift rail members, when the shift fork portions of respective shift rail members are in a neutral state, center axes of all of the respective pillar-shaped portions and the selection axis are arranged as to intersect with each other,
• the arm portion includes a pair of arm portions projecting from the shaft portion in a bifurcated fashion with an opposed angle therebetween, the opposed angle is set in such a manner that the pair of arm portions moves for selection without interfering with the respective shift lug members disposed at appropriate shift positions, and
• the pair of the arm portions move for selection in a direction of the selection axis to select the shift lug member and then swing about the selection axis to apply a pressure in the shifting direction from one side of the pillar-shaped portion of the selected shift lug member by one of the pair of the arm portions to cause the shift fork portion of the shift rail member linked with the shift lug member to perform a shift making operation, and to apply a pressure in the shifting direction from the other side of the selected pillar-shaped portion by the other arm portion to cause the shift fork portion of the shift rail member linked with the shift lug member to perform a shift withdrawing operation.