Patent ID: 8875858

Claim:
A hydraulic control apparatus for a vehicular automatic transmission, which is provided with a first pressure regulating valve of a pressure-relief type for regulating a pressure of a working oil delivered from an oil pump, to a first line pressure, a second pressure regulating valve for regulating said first line pressure of the working oil discharged from said first pressure regulating valve, to a second line pressure, and a lock-up switching valve for switching a lock up clutch provided in a fluid-operated power transmitting device, between its lock-up on state and its lock-up off state, by selecting respective passages of supply of the working oil of said second line pressure to said fluid-operated power transmitting device, said hydraulic control apparatus being configured such that the working oil of a third hydraulic pressure obtained on the basis of said first line pressure is supplied to said lock-up clutch with said lock-up switching valve, in addition to the working oil of said second line pressure, said hydraulic control apparatus comprising: a supply passage connecting/disconnecting valve which is operated, in synchronization with a switching operation of said lock-up switching valve, to supply the working oil of said third hydraulic pressure to said lock-up clutch, when the lock-up clutch is placed in the lock-up on state, and to inhibit the supply of the working oil of said third hydraulic pressure to said lock-up clutch, when the lock-up clutch is placed in its lock-up off state.