| 摘要 |
A gear change mechanism is provided which is intended for a gearbox in which changes of the gear ratio in the gearbox are made mechanically in response to actuating signals. The mechanical movements required are as for a conventional gearbox having a H type pattern. A gearbox selector ( 20 ) is mounted for movement about an axis and in the direction of the axis. The selector is operable by two actuators ( 16 and 18 ), one ( 16 ) to move the selector about its axis and the other ( 18 ) to move it in the axial direction. Each actuator can be similar having a cylinder and a shaft and annular pistons located about the shaft. For the rotational movement of the selector three positions are required, a neutral, a gear engaged position in one direction and a gear engaged position in the other direction. For movements in the direction of the axis two, three or four positions are required depending upon whether it is a two, three or four rail gearbox. An actuator is proposed which is capable of three, four, or more, positions of movement. |
