Hydraulic control system of automatic transmission

A hydraulic control system of an automatic transmission including a plurality of engaging elements, a plurality of hydraulic servos each receiving a hydraulic pressure so as to control the respective engaging elements, and a plurality of shifting means for outputting the hydraulic pressure supplied to the respective hydraulic servo to achieve a plurality of forward speeds by engaging and disengaging the corresponding engaging elements, said hydraulic control system comprising:

• switching means for switching to a predetermined state where a specific speed among said plural forward speeds is achieved by cutting off a hydraulic pressure supply path to a specific hydraulic servo of a group of hydraulic servos which is disengaged when the specific speed is achieved, upon receipt of the output hydraulic pressure from at least one of said shifting means ready for outputting hydraulic pressure when all of the shifting means is in the event of a failure, wherein the switching means is switched by a hydraulic pressure outputted by the shifting means;
• and
• supply switching means, disposed in a hydraulic pressure supply path to a first hydraulic servo that is not included in said specific hydraulic servo, for switching between supply and cut-off states of the hydraulic pressure to the first hydraulic servo.