| 摘要 |
Electrohydraulic control for an automatic gear-box, comprising a selection slide valve (2), at least for the neutral position (N) as well as for the drive mode (D) and reverse mode (R), an electronic control device (3), electrovalves (4) held in the neutral position by the effect of spring action, a source of pressure (1), pressure control valves and gear control valves (5, 6, 7) for actuating the gear engagement and brakes (A-F), as well as a reverse safety valve (8) to prevent engagement of the reverse gear when the forward drive speed is too high, and a system which, in the event of a fault in the electronic circuit, holds or changes the automatic gear-box to a gear ensuring that the maximum permissible engine speed is not exceeded when the vehicle travels at maximum speed. In the event of a failure in the electronic control device (3) during travel, a control system holds or changes the gear, and in the event of a failure in said device (3), before starting or restarting of the engine, this control system (5, 6, 7, 8, 9) engages a lower gear. In the event of a fault in the electronic system during travel, the movement of the vehicle may continue unhampered, even for example in the highest gear, without changing down. In the event of a fault in the electronic circuit when stationary or during a further start of the engine following a failure during travel, a lower gear is engaged to allow starting. |
