Abstract: A direct current motor speed control apparatus is disclosed for controlling the motor speed from zero to base speed primarily by an armature voltage control and for controlling the motor speed from base speed to a rated run speed primarily by field flux control.

Abstract: A specimen or in-service structural member in which strain is to be measured is fabricated as a unit which generates a signal in response to strain occurring in a given region of its surface. A film of piezoelectric material is deposited upon the surface in a manner providing a strong molecular bond between the specimen or member and the piezoelectric film. The film material is chosen from the class having a 6 mm type crystal lattice structure and is formed as a crystalline deposit with the c-axis perpendicular to the surface of the specimen or member. An arrangement of electrodes is provided for direct electrical coupling between spatially separated portions of the piezoelectric film. The electrodes form an output coupling for an electrical signal generated by the piezoelectrically active properties of the piezoelectric film in response to strain mechanically coupled from the substrate surface to the piezoelectric film through the molecular bond.

Abstract: A control valve is disclosed which includes first and second valves. An inverted pendulum is operative with the valves such that when the pendulum rotates in one direction the first valve is opened and the second valve is closed, and when the pendulum rotates in the opposite direction the valve operation is exactly opposite. An electromagnetic device may also be operative with the inverted pendulum which device when energized causes the inverted pendulum to rotate in one direction or the other. The inverted pendulum may also be rotatably biased for holding one valve opened and the other valve closed. The control valve may be used in any number of control systems and is especially suited for use as a master control valve in a vehicle braking system.