Abstract: A lawn mower including an engine having an output shaft, an air impeller, a plurality of cutter blades, and a driven shaft having the air impeller and the cutter blades connected thereto. The driven shaft is connected to the output shaft of the engine through a centrifugal clutch having a drum, and a brake band is located in a path of air drawn by suction by the air impeller for clamping against the outer periphery of the drum of the centrifugal clutch to interrupt rotation of the driven shaft.

Abstract: An aluminum-based die casting alloy for producing high strength, crack free die castings, comprising 4-8% Zn, 6-11% Mg, 0.05-0.45% Ti and/or Zr if desired, and the balance aluminum. In one embodiment, the die casting alloy may further comprise 0.3-2.0% Fe to prevent the die casting alloy in the molten state from eroding the gate and its neighborhood of a die during casting in the die.

Abstract: A cylinder for crankchamber precompression type two stroke engines includes three pairs of main scavenging ports which are symmetrical with respect to a longitudinal plane passing through the centers of the intake and exhaust ports and containing the longitudinal center line of the cylinder. A pair of auxiliary scavenging ports are provided at the opposite sides of the longitudinal plane in such a manner that in a horizontal cross-section the flows from the auxiliary ports do not intersect with the flows from the main ports. Further, the auxiliary scavenging ports are directed further upwardly than the main ports.

Abstract: In an electric shutter operating circuit for use in a photographic camera of the class wherein the operation of the shutter is controlled in accordance with the brightness of an object, and information regarding the iris opening and the photosensitivity of the film used, there are provided a photoelectric element for generating an electric signal corresponding to the brightness, means for generating information signals regarding iris opening and the photosensitivity, a comparator circuit for comparing the electric signal and the information signals, means to feedback the output of the comparator circuit to the input thereof, a memory capacitor connected on the output side of the comparator circuit for storing an electric quantity corresponding to the brightness, an amplifier connected to respond to the terminal voltage of the memory capacitor, and means responsive to the output of the amplifier for controlling the operation of the shutter of the camera.

Abstract: In an electronic shutter operating circuit for use in a photographic camera a differential amplifier comprising a pair of transistors is provided for comparing the photosensitivity of the film used and the brightness of the object to display over exposure and under exposure conditions. A voltage is positively fed back from the output of the differential amplifier to the input thereof to cause it to oscillate for displaying the correct exposure condition. There is provided a transfer switch to cause the differential amplifier to respond to the selected shutter time for closing the shutter when the shutter time expires.