Patent ID: 7862472

Claim:
An automatic transmission, comprising: a plurality of planetary gears; a plurality of frictional engaging elements connected to rotational elements of the respective planetary gears, the automatic transmission achieving a plurality of gear shift stages based on a traveling state of a vehicle by changing clutched and released states of the respective frictional engaging elements and the plurality of gear shift stages including a third gear shift stage achieved by releasing a first frictional engaging element, the first frictional engaging element being clutched at a first gear shift stage and at a second gear shift and the automatic transmission achieving another gear shift stage of a fourth gear shift stage not based on the traveling state of the vehicle but achieved by releasing the first frictional engaging element clutched at the second gear shift stage; a first shift control section configured to perform a gear shift control to shift the gear shift stage between the first gear shift stage and the second gear shift stage by referring to a first gear shift control data used when the gear shift stage is switched between the first gear shift stage and the second gear shift stage; an abnormality state detecting section configured to detect an abnormality state in which both of the first gear shift stage and the second gear shift stage are unachieved due to a failure of at least one of the first frictional engaging element and a second frictional engaging element which is released at both of the first gear shift stage and the second gear shift stage; and an abnormality state gear shift control section configured to perform the gear shift control to shift the gear shift stage between the third gear shift stage and the fourth gear shift stage through the first gear shift control section, while forcefully releasing the first frictional engaging element, when the abnormality state detecting section detects the abnormality state.