Abstract: A cam mechanism for use in a mowing machine. The cam mechanism is comprised of a spur gear and protruding eccentric cams from the top and bottom surfaces of the spur gear. The cam mechanism is formed from a half blanking press process. The eccentric cams are symmetrically formed around a shaft hole located in the center of the spur gear. Members with a hole equaling that of the eccentric cam and shaft hole point symmetry are then fitted onto the eccentric cam. The members are then capable of reciprocation with a phase differential of 180 degrees of each other. The concave portion of the eccentric cam permits lubricants to be filled in the space facilitating the smooth operation of the cam mechanism.

Abstract: A knapsack engine-driven tool driven by an engine provided on a knapsack frame consists of a supporting tool composed of a hollow tube made of a flexible rigid material, preferably of brass, whose base end is fixed onto the knapsack frame, in which the flexible rigid material can be held at a desired shape, a member for operating said engine provided on the edge portion of the hollow tube, a regulating wire which is inserted into the hollow tube for connecting said engine and said operating member, and a flexible protective member for covering said hollow tube. The knapsack engine-driven tool has a metal fixing member, preferably made of iron.

Abstract: An engine muffler is provided which comprises a first expansion chamber for exhaust gas which includes an exhaust gas inlet to be connected to an exhaust port of an engine, a second expansion chamber which includes an exhaust gas outlet, a first exhaust gas purifier in which a catalyst for purifying exhaust gas is coated on at least a concave surface of a concave base body which has a plurality of vent holes passing through the concave surface, the first exhaust gas purifier being disposed in the first expansion chamber such that the concave surface faces the exhaust gas inlet, and at least one second exhaust gas purifier in which a catalyst for purifying exhaust gas is coated on a base body including many pores, the second exhaust gas purifier being disposed between the first expansion chamber and the second expansion chamber. The engine muffler is obtained simply by improving a muffler used for a small-sized engine. The engine muffler has an extremely great effect of purifying exhaust gas.

Abstract: A four-cycle engine in which a mixed gas of a fuel and air containing a lubricating oil is transferred from a carburetor to a cylinder or a crank chamber, the gas is pushed out in the stage of descending the piston to the passage on the reverse side, transferred into a rocker arm chamber including an intake valve at the top of the cylinder via a passage including a valve gear mechanism, and it is directed to the cylinder in the intake stage, whereby the engine is lubricated by the lubricating oil. The engine has no oil pan and can be run at any inclination angle (360.degree.). Also disclosed is that it is also possible for the four-cycle engine to provide a diverged second passage extending to the crank room, to provide a lead valve on a portion of the second the passage, to provide a diverged third passage extending to the lower end of the crank chamber, to provide a lead valve or rotary valve, and to provide a fourth and/or fifth passage(s) to circulate the mixed gas.

Abstract: A four-cycle engine has a base plate provided on a side of the engine and having an opening communicated with a carburetor. A choke plate is pivotally mounted on the base plate, and a choke lever is pivotally mounted on the base plate. A transmitting means is provided for transmitting the opposite rotation of the choke lever to the choke plate so as to rotate the choke plate.

Abstract: A cam gear is mounted on a camshaft, and an intake cam and an exhaust cam are formed on the cam gear for operating an intake valve and an exhaust valve of a hand starting four-cycle engine. A decompression device is rotatably mounted in the cam gear. A decompression cam of the decompression device is exposed from the exhaust cam. The decompression device has a weight, and a spring is provided for urging the weight to the cam shaft. Elastic force of the spring is set so that the weight is urged toward the camshaft in hand starting operation of the engine and moved apart from the camshaft by centrifugal force, thereby projecting the decompression cam in the compression stroke of the engine as to open the corresponding valve.