Auto transmission hydraulic pressure control apparatus

An auto transmission hydraulic control apparatus comprising:

• six friction elements of which two friction elements operate to achieve a corresponding to each stage by means of hydraulic pressure;
• five direct-controlled solenoid valves that individually and directly control hydraulic pressure that is supplied to four friction elements in the six friction elements and equally and directly control hydraulic pressure that is supplied to the other two friction elements;
• an on-off solenoid valve that converts output state and non-output state of hydraulic pressure;
• a switch valve in which one side of a valve spool is supplied by a spring and which selectively supplies hydraulic pressure from one of the direct-controlled solenoid valves, which equally and directly control the hydraulic pressure that is supplied to the two friction element, in accordance with whether hydraulic pressure from the on-off solenoid valve is applied to the other side thereof;
• and
• four fail-safe valves that are disposed between the direct-controlled solenoid valves and the friction elements to structurally limit available arrangements of the friction elements.