| 摘要 |
A hydraulic control apparatus for an automatic transmission including two frictional coupling devices of a first group and a plurality of frictional coupling devices of a second group, the control device including a second-group-engaging switching valve arranged to receive second engaging hydraulic pressures generated to engage the coupling devices of the second group and operable, upon reception of at least one of the second engaging hydraulic pressures, to generate a second-group-engaging pilot hydraulic pressure, and a fail-safe valve to receive at least one of first engaging hydraulic pressures generated to engage the two coupling devices of the first group and operable, upon simultaneous reception of the first engaging hydraulic pressure generated to engage one of the two coupling devices of the first group and the second-group-engaging pilot hydraulic pressure, to prevent application of the first engaging hydraulic pressure to the other of the two coupling devices of the first group.
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