Abstract: A cam drive is provided for a valve control of a mixture-lubricated internal combustion engine that has a cylinder, and a cylinder head in which is disposed a poppet valve which is actuated by a pivotable rocker arm. Mounted in a cam chamber is a control cam that is driven by the crankshaft of the engine and on the cam path of which rests a drag lever that transfers the cam lift to the rocker arm. To achieve a reliable mixture lubrication, a flow guidance element is disposed in the annular chamber between the peripheral wall of the cam chamber and the maximum diameter of the path of a cam nose. The flow guidance element is provided with a flow edge that is disposed adjacent to the drag lever in the vicinity of the path diameter of the cam nose.

Abstract: A portable handheld work apparatus such as a motor-driven chain saw includes a housing (6) of a drive unit (2). The following are mounted in the housing (6): an internal combustion engine (3), a carburetor (4) for fuel metering and an air filter (5) as well as a fuel tank (8). The air filter (5) is mounted ahead of the carburetor in the flow direction of the fresh air flow. A largest possible filter action is obtained with a compact configuration in that a housing (10) of the air filter (5) lies at least partially in a space between the carburetor (4) and the fuel tank (8).

Abstract: A diaphragm carburetor is provided for an internal combustion engine that operates with scavenging air, especially a two-cycle engine in a manually-guided implement. The carburetor has an intake channel portion in which is disposed a butterfly valve that is rotatably held via a shaft and in the vicinity of which fuel-supplying channels open into the intake channel portion. The channels are supplied from a fuel-filled regulating chamber that is formed on a longitudinal side of the intake channel portion in the carburetor housing and is separated by a regulating diaphragm from a compensation chamber. The carburetor has at least one air channel that supplies additional combustion air and that has an air valve that is rotatably held via a shaft.

Abstract: A valve drive mechanism is provided that has a rocker arm that by means of a swivel joint is movable about a pivot axis that extends transverse to the rocker arm. A control unit serves to actuate one end of the rocker arm, the other end of which actuates a poppet valve. A guide element, which is disposed between the end of the valve stem of the poppet valve and the other end of the rocker arm, serves to secure the position of the other end of the rocker arm relative to the valve stem end. The guide element is separate from the rocker arm and valve stem, and the other end of the rocker arm comes to rest between abutment surfaces of the guide element.

Abstract: A valve drive mechanism is provided for an internal combustion engine, especially a four-stroke engine in a power chain saw. The implement housing is spanned by a front handle, the tubular grip of which is adjacent to the cylinder head of the engine and extends from one longitudinal side of the implement to the other longitudinal side thereof. A rocker arm of a valve control is pivotably mounted on the cylinder head between the ends of the rocker arm, with the rocker arm being pivotable about a pivot axis disposed transverse to the rocker arm. Push rods of a control mechanism engage one end of the rocker arm to actuate a poppet valve, on the valve stem of which the other end of the rocker arm acts. To be able to guide the tubular grip close to the center of gravity of the implement, the longitudinal axis of the rocker arm is disposed approximately parallel to the adjacent portion of the tubular grip.

Abstract: An inlet conduit is provided for a valve-controlled internal combustion engine, and also provided is a method for producing a flow deflection edge in an inlet conduit. In the region where the supply passage portion and the valve end passage portion of the inlet conduit meet, a cylindrical rod is guided through the cylinder head of the internal combustion engine. Portions of the peripheral surface of the rod form portions of the passage wall of the inlet conduit.

Abstract: A cam drive is provided for a valve-controlled mixture-lubricated internal combustion engine having a cylinder in which is formed a combustion chamber that is delimited by the cylinder wall, a piston and a cylinder head. Disposed in the cylinder head are poppet valves, the respective valve shafts of which are driven via a pivotable rocker arm from a valve control that includes a control cam on the surface of which rests a contact lever that transfers cam lift to one end of the rocker arm. To ensure good lubrication of the cam drive even at high speeds, the control cam is rotatably mounted in the vicinity of the cylinder wall, in which is formed a through-bore. The first open end of the through-bore is disposed in the cylinder bore at the level of the piston in its lower dead center position, while the second open end opens into the cam chamber in the vicinity of the control cam.

Abstract: A portable handheld work apparatus such as a motor-driven chain saw includes a housing (6) of a drive unit (2). The following are mounted in the housing (6): an internal combustion engine (3), a carburetor (4) for fuel metering and an air filter (5) as well as a fuel tank (8). The air filter (5) is mounted ahead of the carburetor in the flow direction of the fresh air flow. A largest possible filter action is obtained with a compact configuration in that a housing (10) of the air filter (5) lies at least partially in a space between the carburetor (4) and the fuel tank (8).

Abstract: A valve drive having a rocker arm mounted on a cylinder head is provided. One end of the rocker arm is actuated by a push rod to actuate a valve stem of a poppet valve that engages the other end of the rocker arm, which is pivotably held between its ends on a support pin that extends into the cylinder head, with a spherical mounting being provided between the support pin and the rocker arm. Provided on that side of the rocker arm remote from the cylinder head is a bolt head for adjusting the bearing spacing between the rocker arm and the cylinder head for adjusting valve play. To prevent unintended adjustment of the bolt head, the latter cooperates with a rotation preventing element that has an arresting portion that engages the bolt head, and a support portion that conveys the adjustment moment away.

Abstract: The invention relates to a vibration damper between a housing (4), which holds an internal combustion engine, and a handle (3) fixed on the housing (4). The handle (3) is for holding and guiding the motor-driven chain saw (2) during use thereof. The vibration damper (1) is a coil spring (5) which is fixed at a first end (10) thereof with an attachment element (7) to the handle (3) and, at a second end (20), the coil spring is fixed with a further attachment element (30) to the housing. A part turn of the end (10, 20) of the coil spring (5) is held form-tightly to the attachment element (7, 30) in the direction of its longitudinal center axis (25). To provide a torsion-free assembly of the coil spring, it is provided that the coil spring (5) can be assembled from one of its ends (20) between the handle (3) and the housing (4) and be secured at least at one of its ends (20) to the attachment element (30) against a rotational movement in the peripheral direction.

Abstract: A cam drive is provided for a valve-controlled mixture-lubricated internal combustion engine having a cylinder in which is formed a combustion chamber that is delimited by the cylinder wall, a piston and a cylinder head. Disposed in the cylinder head are poppet valves, the respective valve shafts of which are driven via a pivotable rocker arm from a valve control that includes a control cam on the surface of which rests a contact lever that transfers cam lift to one end of the rocker arm. To ensure good lubrication of the cam drive even at high speeds, the control cam is rotatably mounted in the vicinity of the cylinder wall, in which is formed a through-bore. The first open end of the through-bore is disposed in the cylinder bore at the level of the piston in its lower dead center position, while the second open end opens into the cam chamber in the vicinity of the control cam.

Abstract: An inlet conduit is provided for a valve-controlled internal combustion engine, and also provided is a method for producing a flow deflection edge in an inlet conduit. In the region where the supply passage portion and the valve end passage portion of the inlet conduit meet, a cylindrical rod is guided through the cylinder head of the internal combustion engine. Portions of the peripheral surface of the rod form portions of the passage wall of the inlet conduit.

Abstract: A valve drive mechanism is provided that has a rocker arm that by means of a swivel joint is movable about a pivot axis that extends transverse to the rocker arm. A control unit serves to actuate one end of the rocker arm, the other end of which actuates a poppet valve. A guide element, which is disposed between the end of the valve stem of the poppet valve and the other end of the rocker arm, serves to secure the position of the other end of the rocker arm relative to the valve stem end. The guide element is separate from the rocker arm and valve stem, and the other end of the rocker arm comes to rest between abutment surfaces of the guide element.

Abstract: A valve drive mechanism is provided for an internal combustion engine, especially a four-stroke engine in a power chain saw. The implement housing is spanned by a front handle, the tubular grip of which is adjacent to the cylinder head of the engine and extends from one longitudinal side of the implement to the other longitudinal side thereof. A rocker arm of a valve control is pivotably mounted on the cylinder head between the ends of the rocker arm, with the rocker arm being pivotable about a pivot axis disposed transverse to the rocker arm. Push rods of a control mechanism engage one end of the rocker arm to actuate a poppet valve, on the valve stem of which the other end of the rocker arm acts. To be able to guide the tubular grip close to the center of gravity of the implement, the longitudinal axis of the rocker arm is disposed approximately parallel to the adjacent portion of the tubular grip.

Abstract: A cam drive is provided for a valve control of a mixture-lubricated internal combustion engine that has a cylinder, and a cylinder head in which is disposed a poppet valve which is actuated by a pivotable rocker arm. Mounted in a cam chamber is a control cam that is driven by the crankshaft of the engine and on the cam path of which rests a drag lever that transfers the cam lift to the rocker arm. To achieve a reliable mixture lubrication, a flow guidance element is disposed in the annular chamber between the peripheral wall of the cam chamber and the maximum diameter of the path of a cam nose. The flow guidance element is provided with a flow edge that is disposed adjacent to the drag lever in the vicinity of the path diameter of the cam nose.

Abstract: A mounting mechanism for an adjustable component that is to be held against an abutment surface of a housing, especially for the guide bar of a power chain saw, is provided. The mechanism includes at least two bolts that are provided on the housing, are spaced from one another, and project beyond the abutment surface of the housing and into an elongated opening of the component. At least one device is provided that extends into a gap between one of the bolts and at least one of the longitudinal edges of the elongated opening for engaging such at least one longitudinal edge.

Abstract: The invention is directed to a start-assist device on a membrane carburetor of an internal combustion engine in a motor-driven chain saw which is to be started manually. The carburetor includes a control chamber delimited by a control membrane. The control chamber is supplied with fuel from a fuel tank via control valve. The control valve is opened by the control membrane when the underpressure builds up in the control chamber so that fuel flows in. This fuel is supplied to the air-inducting intake channel via an idle nozzle and a main nozzle. The fuel feed system further has an outlet for vapor bubbles or the like. A pump which is driven indirectly from the start operation is provided and has a suction connection connected to the outlet in order to ensure, with few start attempts, a reliable start of the engine independently of the temperature state of the engine and other influences.