| 摘要 |
PURPOSE:To make it possible to prevent with a simple constitution a backward transmission system from being established at the time of foward runing above a prescribed vehicle speed by using a shift valve inserted into a circuit for establishing the forward transmission system in common to a mis-operation preventing valve. CONSTITUTION:A hydraulic circuit 8 controlling the operations of each clutch C1-C3 and a select gear (drawing omitted) for respectively establishing each transmission system from forward 1 speed to 3 speed and backward transmission system is equipped with a shift valve 11, etc., comprising a manual valve 9 and each shift valve 11-1, 11-2 for 1-2 speed change and 2-3 speed change respectively. In this case, by arranging, e.g., the valve 11-2 among the componeits of shift valve 11 to be controlled only by a vehicle speed signal serving as a governer pressure because the input of a throttle opening signal from a throttle valve 12 is cut off at the ''R'' position of the manual valve 9, the valve 11 is used in common to a mis-operation preventing valve 15. |
