| 摘要 |
PURPOSE:To have the desired operational running even in the event of any failure in a sensor etc. by performing transmitting in the applicable operation specified position with pushing of a speed change button over a certain period of time. CONSTITUTION:With a speed change control device CPU an automatic transmission is formed which automatically performs speed changing in accordance with the current condition by sensing different operational running conditions at the time of works with a tractor, and for ex. the load on the working device concerned is sensed by a load sensor 31, and solenoid valves V1-V8 are output according to the size of the load when it exceeds the reference value to have deceleration to optimum gear ratio followed by acceleration eventually when the load becomes light. Thus automatic speed change is made. The solenoid valves V1-V8 in this specified position are output for speed changing by pushing one of the specified positions of either of speed change operating buttons S1-S8 continuously for a certain period of time (for ex. 2sec), wherein this speed change process takes place regardless of eventual trouble, abnormality, etc. of any of the load sensors 31 etc. of this automatic transmission. |
