Hydraulic control apparatus for automatic transmission

摘要

To prevent the neutral state from being formed in a change gear apparatus and allow the obtaining of an intended gear change appropriately during a servo malfunction. Hydraulic servos engage and disengage a plurality of friction engagement elements; a hydraulic pressure supply system supplies the hydraulic servo of a predetermined friction engagement element with hydraulic pressure; and an auxiliary hydraulic pressure supply systems supplies a predetermined hydraulic servo with another hydraulic pressure, in the case where the hydraulic pressure supply system is placed in a first unsupplied state where the hydraulic pressure supply system cannot supply the hydraulic servo of the predetermined friction engagement element with hydraulic pressure. The auxiliary hydraulic pressure supply system does not supply the predetermined hydraulic servo with the other hydraulic pressure, in the case that the hydraulic pressure supply system is placed in a second unsupplied state where the hydraulic pressure supply system does not supply the hydraulic servo of the predetermined friction engagement element with hydraulic pressure.