| 摘要 |
PURPOSE:To reduce the driving loss of an oil pump and improve the fuel consumption by constituting an automatic transmission equipped with a lock-up mechanism so that the line pressure in a control circuit is cut-back when the captioned apparatus is locked-up. CONSTITUTION:A control circuit 60 which feeds the working-oil pressure onto a plurality of frictional engagement means for obtaining a plurality of speed- change stages in an automatic transmission and onto a lock-up mechanism directly connecting a torque converter is equipped with a selector valve 64, 1-2 shift valve 68, and a 2-3 shift valve 76 etc. In this case, a lock-up control valve 99 for operating the lock-up mechanism through the upward movement of a spool 99d in the case when a solenoid 99a is energized is provided as a lock-up detecting means. The hydraulic pressure as a cut-back signal is introduced into the port 98a of a cut-back valve 98 through a line 103, when the lock-up control valve 99 operates, and the cut-back valve 98 is operated, and the adjusted value of the line pressure by a pressure adjusting valve 63 is reduced by operating the cut-back valve 98, and the line pressure is cut-back. |
