Abstract: A two-cycle engine in a portable, manually-guided implement, such as a power chain saw, a cut-off machine, a brush cutter, or the like, is provided. The cylinder has a combustion chamber that is delimited by a reciprocating piston that via a connecting rod drives a crankshaft that is mounted in a crankcase so as to be rotatable about a crankshaft axis. The cylinder has an outlet for conveying exhaust gases out of the combustion chamber, with the outlet having an axis of the channel thereof. The cylinder also has an inlet for supplying a fuel/air mixture to the crankcase. By means of at least two transfer channels, the fuel/air mixture is conveyed out of the crankcase and into the combustion chamber, with the transfer channels being disposed symmetrically relative to the axis of the channel of the outlet.

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: The invention is directed to a carburetor arrangement in a work apparatus having an internal combustion engine (2). The inlet channel (7) of the engine is connected via a connecting tube (8) to the intake channel section (9) of the membrane carburetor (4). The connecting tube (8) projects through a partition wall (3) arranged between the engine (2) and the carburetor (4). The carburetor (4) is fixed against the partition wall (3). Also, an intake air filter (70) is provided and supplies combustion air. The intake air filter is connected to the end (19) of the intake channel section (9) facing away from the partition wall (3). An attachment of the carburetor is provided without tools in that the carburetor is held clamped in the longitudinal direction of the intake channel section (9) between the partition wall (3) and a wall (22) of the air filter housing (20).

Abstract: A carburetor arrangement for an internal combustion engine including a two-stroke engine in a portable handheld work apparatus includes an intake channel section (2) which is formed in the carburetor housing (34). A throttle flap (3) is arranged in the intake channel section and is rotatably held by a throttle flap shaft (4). Fuel-conducting channels open into the intake channel section (2) in the region of the throttle flap. A choke flap (5) is mounted upstream of the throttle flap (3) in the intake channel section (2). The choke flap (5) is held by a choke shaft (6) so as to be rotatable. The throttle flap (3) is displaced in a closing direction from an opening position into a closed position and in an opening direction from the closed position into the open position. The same applies to the choke flap (5). The choke flap (5) and the throttle flap (3) are mechanically coupled. The choke shaft (6) is actuable by an operator-controlled element.

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 method is provided for producing a crank arm for a crankshaft of an internal combustion engine, wherein the crankshaft is composed of separately produced parts. The crank arm is stamped out of a semifinished part and has a central recess for receiving a shaft journal of the crankshaft, and has an eccentrically disposed recess for receiving a crankshaft pin. A peripheral contour of the stamped part delimits a flywheel member of the crank arm. A recessed surface portion is formed or stamped in the crank arm in an area surrounding the central recess.

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: 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 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 hand-held working tool has a housing and an internal combustion engine arranged in the housing and comprising a crankshaft and an air filter. A tool is driven by the crankshaft of the internal combustion engine. A fan housing is attached to the engine housing and has an air inlet. A fan wheel is arranged in the fan housing and is driven by the crankshaft of the internal combustion engine to supply cooling air, sucked in through the air inlet, to the internal combustion engine. The fan housing has a bottom extending radially to the crankshaft. The bottom and a side of the fan wheel facing the bottom define a chamber in the fan housing. The bottom has a combustion air outlet. A combustion air channel is connected to the combustion air outlet and to the air filter. The combustion air outlet is axially supplying combustion air from the chamber through the combustion air channel into the air filter of internal combustion engine.

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: A diaphragm carburetor for a combustion engine having a manual starter has a housing and a control chamber arranged in the housing and filled with fuel. A suction channel is arranged in the housing and has a venturi section. A throttle flap is rotatably supported in the suction channel downstream of the venturi section in the flow direction of combustion air sucked into the suction channel. A main valve path connects a control chamber to the venturi section. An idle valve path connects the control chamber to the suction channel and opens into the suction channel at a location downstream of the throttle flap in the flow direction. A choke flap is rotatably supported in the suction channel and positioned upstream of the venturi section. The choke flap has identical cold start and warm start positions and allows a flow volume of combustion air into the suction channel sustaining engine operation after the engine has been started.

Abstract: A closure arrangement of a container has fill socket with an inner thread and a closure cap with a cylindrical base body having an outer thread matching the inner thread of the fill socket of the container. The cylindrical base body has an annular flange adjacent to the outer thread. An annular seal, connected to one side of the annular flange facing the outer thread, is provided for sealingly resting on the rim of the fill socket when the closure cap is threaded into the fill socket. The outer thread has a resilient tongue extending in the circumferential direction of the cylindrical body and has a radial projection cooperating with the abutment of the matching inner thread. The radial projection, when the closure cap is threaded into the fill socket, catches in a catch position behind the abutment before a fully closed position of the closure cap in the fill socket is reached.

Abstract: A tank closure for a fill opening of a fuel tank has a closing device extending axially through the fill opening of the fuel tank. The closing device includes a grip for actuating the closing device. The closing device also includes a first clamping member and a second clamping member movable axially toward one another. The first clamping member has a first clamping surface and the second clamping member has a second clamping surface. The first and second clamping surfaces face one another and define therebetween an annular chamber. The first and second clamping surfaces are positioned at an angle .alpha. to one another. The closing device also includes a radially elastically expandable sealing ring positioned in the annular chamber.

Abstract: An actuating device for a decompression valve of an internal combustion engine with a cable starter, wherein the decompression valve is positioned within the cylinder of the internal combustion engine and comprises a valve member biased into its closed position, has a transmission lever having a longitudinal extension and being rotatable about its longitudinal axis. The transmission lever has a first and a second end. A cable drum for receiving the starter cable of the cable starter is provided. The cable drum has an axis of rotation about which the cable drum is rotated when the starter cable is pulled. The longitudinal axis of the transmission lever is perpendicular to the axis of rotation of the cable drum and spaced from the rotational plane of the cable drum.

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.