Abstract: A rotary actuator derives its power from a synchronous motor preferably of the AC type providing constant output speed, and from a non-synchronous motor, preferably of the DC type, in a helper capacity to provide additional torque for a load. Use of certain types of non-synchronous motors to provide a portion of the maximum torque is cheaper than using a synchronous motor whose size is adequate for the maximum torque requirement. A torque limiting clutch which couples the non-synchronous motor output to the synchronous motor output allows the non-synchronous motor to run compatibly with the synchronous motor. A hysteresis coupling type of torque limiting clutch is preferred. In a preferred embodiment, both of the motors drive a gear train, with the non-synchronous motor coupled to the gear train by the torque limiting clutch.

Abstract: A rotary actuator uses a two degree of freedom gear train with three torque members to provide torque to the output element from a first torque member. The torque is supplied to a second torque member from a drive motor. A torsion spring on the third torque member is normally wound tight and held wound by a brake which locks the third torque member during normal operation when electrical power is available for the drive motor. When power is lost, the brake releases the third torque member, allowing the spring to apply torque to the third torque member to drive the output element through the first torque member to a return position. This allows loads such as valves to be returned to a safety condition upon loss of electrical power to the system of which the load and the actuator are a part.

Abstract: A stop pin which has a forward end and a latching end is employed between spaced plates or walls having aligned apertures. The latching end of the stop pin has locking buttons formed on longitudinal faces of the stop pin and a shoulder spaced from the locking buttons by the thickness of the first plate. The forward end of the stop pin is inserted through the first aperture and into the second aperture. Additional axial force on the stop pin forces the lock button through the first aperture by rotating the latching end into relieved portions of the first aperture while the forward end of the stop pin opposes rotation. After the stop buttons pass through the first plate the pin straightens and is latched with the stop button and the shoulder on opposite sides of the first plates.

Abstract: A permanent magnet, alternating current motor having a variable hysteresis output coupling has an annular permanent magnet rotor caused to rotate within a stator structure. This permanent magnet rotor is capable of being shifted laterally to engage or disengage a hysteresis drag cup output device. With this arrangement either an off-on output torque can be provided, or the output torque can be modulated.

Abstract: An averaging temperature responsive apparatus for use in an air conditioning system to measure the average temperature of air passing through a duct has a tube extending transversely across the air duct. The tube has a series of spaced inlet openings on the upstream side and at least one exhaust opening on the downstream side. A temperature responsive element is mounted adjacent to the exhaust opening. Each of the inlet openings is made by cutting the tube and bending a portion of the tube inward so that upon air entering the inlet opening, the air is directed through the tube in a direction toward the exhaust opening.