Abstract: A connecting rod for reciprocating piston machines having piston pin and crankshaft ring portions with bores therein connected together by a load bearing member. The load bearing member has voids within it adjoining the outer perimeters of the piston pin and crankshaft ring portions. When press-fitting a liner or cup bearing within the ring portion bores, the voids allow the piston pin and crankshaft ring portions to expand radially uniformly at the connection between the ring portions and the load bearing member such that the liner and bearing retain a substantially circular shape.

Abstract: A two cycle crankcase scavenged internal combustion engine having an exhaust gas recirculation system. Exhaust gas from the coolest part of the exhaust muffler is recirculated back to the crankcase in a controlled discrete charge on each cycle of the engine. A recirculation port extends through the cylinder sidewall and is opened briefly during the compression stroke of the piston to thereby enhance vaporization of the fuel and increase velocity of the scavenging air-fuel mixture into the combustion chamber.

Abstract: An arrangement for mounting a two-stroke cycle vertical crankshaft internal combustion engine on a rotary mower deck to accept a four-stroke cycle vertical crankshaft internal combustion engine whereby either type engine may be adapted to the same mower deck is disclosed including a feature for minimizing the risk of crankshaft or crankcase damage in the event of impact of the rotating mower blade with a relatively immovable object. By employing the adapted which allows mounting of the two-stroke cycle engine on the mower deck to also reinforce the lower region of the engine crankcase where the crankshaft extends from the crankcase a lighter weight, cheaper construction of the two-stroke cycle engine is possible.

Abstract: A method of assembling a piston, connecting rod, wrist pin, and yoke thrust bearing is disclosed wherein the method comprises the steps of disposing between the piston and connecting rod, a one-piece yoke thrust bearing thereby providing a bearing surface between a wrist pin boss and the connecting rod. The piston includes a pair of wrist pin bosses disposed therein and in spaced-apart facing relationship. The bosses have oppositely disposed faces with axially aligned bores therein, and the faces have disposed therein respective shoulder-like depressions. The yoke thrust bearing comprises a pair of washer portions in abutment against respective boss faces and interconnected by a yoke element, and the washer portions have respective projections conformably received in respective depressions, thereby aligning the holes in the washers with the bores and preventing rotation of the yoke thrust bearing in the piston.

Abstract: A piston and connecting rod assembly comprises a one-piece yoke thrust bearing disposed between the piston and connecting rod to provide bearing surfaces therebetween. The piston includes a pair of wrist pin bosses disposed therein and in spaced-apart facing relationship. The bosses have oppositely disposed faces with axially aligned bores therein, and the faces have disposed therein respective shoulder-like depressions. The yoke thrust bearing comprises a pair of washer portions in abutment against respective boss faces and interconnected by a yoke element, and the washer portions have respective projections conformably received in respective depressions, thereby aligning the holes in the washers with the bores and preventing rotation of the yoke thrust bearing in the piston. On end of the connecting rod is received between the washer portions, and a wrist pin is passed through the boss bores, washer portions, and the connecting rod opening to thereby pivotally connect the piston and connecting rod together.

Abstract: Techniques for forming one piece connecting rods for coupling a piston and crankshaft to convert between reciprocating and rotary motion as might be used in an internal combustion engine or piston-type compressor are disclosed wherein the connecting rod is formed of a lightweight material such as aluminum, which material is of an inadequate hardness to form a roller bearing race. The rod includes an elongated arm portion having enlarged annular portions at opposite ends thereof and with one of those annular portions having an inner surface for receiving, in a press fit manner, a hardened steel liner to provide an outer bearing race. Rollers are then interposed between this outer race and an eccentric portion of a crankshaft while the other enlarged annular portion receives a roller bearing assembly for connection to a piston wrist pin.

Abstract: A carburetion system for an internal combustion engine having improved fuel metering is disclosed and includes a fuel supply conduit which is formed in a portion of the body of the carburetor extending from a fuel source to the carburetor bore with that carburetor body portion having a first linear temperature coefficient of expansion. A mixture control member formed of a material having a second linear temperature coefficient of expansion engages the body in a first region and defines relative to the carburetor body in a second remote region a fuel metering orifice for controlling fuel flow through the fuel supply conduit. The mixture control member may be moved relative to the first and second regions to change the fuel to air ratio supplied to the engine. Employing a fuel metering orifice in the adjustable fuel metering arrangement, the minimum flow area of which has a simply connected convex cross sectional configuration, minimizes the adverse effects of ambient temperature changes.

Abstract: An ignition timing method and apparatus is disclosed for presetting the ignition timing of an internal combustion engine having an engine driven shaft and a wheel supported on that shaft carrying a portion of the ignition system with another portion of that ignition system supported by the engine in a relatively fixed position adjacent the wheel. A slot is provided in the shaft surface extending generally in the direction of the axis of rotation of the shaft and a further slot is provided along an inner hub of the wheel. A selected one of several different keys including spacer keys of a generally frustoconical configuration having an outer protuberance for engaging a keyway in the wheel hub and an inner protuberance for engaging a keyway in the shaft is selected and positioned intermediate the shaft and hub to fix the relative angular orientation between the shaft and hub with those keys of the frustoconical sleeve configuration compensating for the dissimilarity in the size between the hub and shaft.

Abstract: An automatic compression release mechanism for an internal combustion engine wherein first and second opposed cantilevered ends of a centrally supported flexible plate forms two independently operating valves to respectively control serially connected inlet and outlet ports of a valve chamber forming a part of a compression release passageway connecting the combustion chamber of the engine with a zone of lower pressure such as the cylinder sidewall exhaust port of a two-cycle engine. The valves are each one-way check valves operating oppositely to one another. The valve controlling the outlet port is normally biased to an open position and remains open when the engine is turned over at the relatively slow cranking speeds normally used to start the engine, relieving somewhat engine compression, thereby facilitating the starting of the engine.

Abstract: A split steel connecting rod bearing liner for internal combustion engines comprising two generally semicircular liner halves formed of steel having inner bearing surfaces which are hardened and including a generally semicircular peripheral reinforcing groove formed in each of the halves. The grooves each comprise a peripheral depression in the inner surface and a corresponding peripheral ridge on the outer surface directly opposite the depression and may be formed by stamping or another suitable metal forming operation. The connecting rod includes a circumferential groove in the crank pin opening within which the liner grooves are disposed so as to prevent lateral movement of the liner.