DE 44 22 257 C1 discloses a parking lock with emergency release means for an automatic motor vehicle transmission. The parking lock comprises a parking lock gearwheel and a locking pawl that can be actuated by a selector spindle driven by an electric motor. Emergency release is effected by means of a Bowden cable which activates a spring, via a release lever, for actuating the locking pawl.
DE 198 34 156 A1, by the present applicant, discloses a device for actuating a parking lock by means of a so-termed energy spring, which comprises a positionally fixed parking lock cylinder and a piston that can move therein to actuate a locking element (for example a locking cone) of the parking lock. The piston, also referred to as the control element, is pushed in a first direction, i.e., to engage the parking lock, by a compression spring and is moved back in the opposite direction, i.e., to release the parking lock, by the action of a pressure medium. In this end position, the piston is mechanically locked by means of an electromagnet so that, while the vehicle is moving, the locking pawl cannot fall into the parking lock gearwheel.
From the textbook “Fahrzeuggetriebe (Vehicle transmissions)” by H. Naunheimer et al., 2nd Edition 2007, pages 371, 372 an electrically activated parking lock, by the present applicant, is known. The known actuating device comprises a piston that can move in a parking lock cylinder, which acts upon a rotatably mounted parking disk which, for its part, comprises, via a connecting rod, a locking cone for locking and releasing a locking pawl. In the event that the actuating device has failed, an emergency release device by means of a Bowden cable is provided, which engages with the parking disk and locks the locking pawl. Thus, in its disengaged condition the parking lock is secured. An emergency release of this type can prove necessary if a vehicle with a defective parking lock has to be towed away.