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An actuating unit for an aircraft remotely controlled element, comprising a motor including a drive shaft and a pair of field coils for rotating said shaft in opposite directions, an output shaft, complemental jaw clutch elements between said shafts, said clutch elements being adapted to be engaged to establish the driving relation between said shafts and disengaged to break the driving relation, a solenoid controlling said jaw elements, a solenoid switch for each of said field coils, a pair of spaced limit switches operatively connected to said solenoid and solenoid switches, a member movable between said limit switches to actuate one or the other, means drivably connected to said output shaft to cause movement of said member to engage one of said limit switches after a predetermined number of revolutions of said output shaft, contact means included in the circuit of said solenoid switches, and means to control said contact means from said jaw clutch elements whereby engagement of said clutch elements makes the contact and disengagement of the clutch elements breaks the contact.