Control device for automatic transmission

摘要

A second shift valve for a lock-up clutch is switched in response to supply of an R range pressure and a solenoid pressure from a low-and-reverse solenoid valve to selectively supply an output from a lock-up solenoid valve to a pressure reduction control valve or a lock-up control valve. The pressure reduction control valve regulates a line pressure at a small gain by the output from the lockup solenoid valve via the second shift valve. The first shift valve actuated by the solenoid pressure from the low-and-reverse solenoid valve selectively supplies a high R range pressure from a manual valve or an output from the pressure reduction control valve to the low-and-reverse brake. This enables accurate hydraulic control of the low-and-reverse brake and ensures the required torque capacity with simple arrangement.