Abstract: A mechanical power transmission apparatus, of the differential gear type, for actuating an airplane control surface requiring two independent actuator inputs to a single control surface. Predetermined, proportionately variable, asymmetric loads between the two actuators are accomodated by a load sensitive brake in conjunction with a fuse link which fails in the event of single actuator or drive means failure. The fuse link is provided by employing a shear pin to attach the pinion gear in the differential to the pinion shaft. The shear pin failure strength in conjunction with the load variable brake determines the allowable differential torque between the two driven bevel gears.

Abstract: Method and apparatus for efficient operation of a brushless d-c motor are shown. A brushless d-c motor comprises, essentially, a motor drive source, such as a d-c to a-c converter, in combination with a conventional brushless a-c machine. Generally, the brushless a-c machine includes a polyphase stator for the production of a rotating electric field, and a rotor that produces mechanical power from the rotating field without the need for sliding electrical contacts. For induction motors, the rotor phases are short-circuited and rotor currents are produced by allowing the rotor to "slip" with respect to the rotating stator field, the resulting flux variations in the rotor thereby inducing rotor currents. Motor speed is controlled by frequency control of the a-c output from the motor drive source.