Actuator for an automatic transmission provided with electrical actuation

FIG. 1 shows the actuator of an electric actuating device of an automatic transmission according to the invention, whose electric drive 1 comprises a relatively small motor 1 which does not have a very high output. This motor 1 is coupled with the self-locking worm gear unit 2. The vehicle which is in the parked position and which has been parked on a slope has exerted a force on the transmission, in the present case on the automatic transmission 3, due to the descending force of the slope. Because of the inclined position, a high force is required after parking to remove the detent from the parking ratchet wheel again. The four-bar linkage transmission is designed in such a way that the cranks 8, 9 at the automatic transmission 3 and at the worm gear unit 2 are rotated relative to one another via the coupling rod 4 in the parked position such that the coupling rod 4 assumes a very acute angle with the crank 9 at the worm gear unit 2. The lever ratios between A1 and A2 are accordingly