| 摘要 |
PURPOSE: To provide a downshift preventing device capable of appropriately taking measures while self-diagnosing a fault of various detecting element or sensor by preventing the downshift from a second speed gear to a first speed gear at the time of high-speed operation of a vehicle. CONSTITUTION: This downshift preventing device is provided with a first and a second actuators 10, 12 to be actuated by the pressure oil from a pressure oil supplying source 18 and for setting the change gear ratio of a first speed and second speed, and a manual shift valve 30 to be manually operated between a first and a second positions so as to feed the pressure oil to the first and the second actuators at the first and the second positions. This device also includes a solenoid valve 34 to be moved between the first and the second positions and for switching a flow passage at the second position so that the pressure oil is supplied to the only second actuator while not switching the flow passage at the first position, and includes solenoid valve control means 38, 40, 42 for hindering the downshift while moving the solenoid valve to the second position in the case of moving the manual shift valve from the second position to the first position at the engine speed more than the predetermined value. |
