Abstract: A valve stem seal (10) for a combustion engine may comprise a cylindrical body (12) including a mounting portion (16) and a valve stem sealing portion (14) integrally formed with the mounting portion (16), and an o-ring (26) configured for sealing engagement with a valve stem reciprocating in a valve guide (40) of a valve of the combustion engine. The mounting portion (16) may define an opening (18) for receiving an upper end (43) of the valve guide (40) and may be configured for substantially fluid-tight engagement with the upper end (43) of the valve guide (40). The valve stem sealing portion (14) may include an annular groove (22) formed in an inner surface of the cylindrical body (12). The o-ring (26) may be received in the annular groove.

Abstract: A chainsaw includes an internal combustion engine with a fuel-air mixture inlet and a carburettor with a fuel-air mixture outlet disposed in the direction of flow of a fuel-air mixture in front of the fuel-air mixture inlet. A fuel-air mixture channel is provided between the fuel-air mixture outlet and the fuel-air mixture inlet. A lubricant guide is provided along components to be lubricated, such that the lubricant circuit is connected particularly effectively to the fuel supply of the internal combustion engine. A removal device for fuel with a recess which receives fuel and supplies the lubricant guide is provided between the fuel-air mixture outlet and the fuel-air mixture inlet.

Abstract: A drive system for a tool, particularly a chain saw, includes a fresh air inlet and an intake manifold arranged after the fresh air inlet in the flow direction of the fresh air that opens into a carburettor. A combustion engine is provided that is arranged after the carburettor in the flow direction of an air-fuel mixture produced in the carburettor, in which the carburettor is exposed to a lower level of thermal stress. At least one heat conducting cooling vane is connected to the carburettor and protrudes outwards into direct contact with the ambient fresh air.

Abstract: An internal combustion engine includes a cylinder wall through which an exhaust port with an exhaust port inner surface is routed from a combustion chamber to an exhaust port opening in the cylinder wall. A pipe section is arranged in a section of the exhaust port following the exhaust port opening in the direction of the combustion chamber with a pipe section outer surface, which reduces the heat transfer from the exhaust gas from the exhaust port into the cylinder wall. The pipe section outer surface is spaced from the exhaust port inner surface through an air gap by sections along an entire outer circumference of the pipe section.

Abstract: A drive system for a tool, particularly a chain saw, includes a fresh air inlet and an intake manifold arranged after the fresh air inlet in the flow direction of the fresh air that opens into a carburettor. A combustion engine is provided that is arranged after the carburettor in the flow direction of an air-fuel mixture produced in the carburettor, in which the carburettor is exposed to a lower level of thermal stress. At least one heat conducting cooling vane is connected to the carburettor and protrudes outwards into direct contact with the ambient fresh air.

Abstract: A chainsaw includes an internal combustion engine with a fuel-air mixture inlet and a carburettor with a fuel-air mixture outlet disposed in the direction of flow of a fuel-air mixture in front of the fuel-air mixture inlet. A fuel-air mixture channel is provided between the fuel-air mixture outlet and the fuel-air mixture inlet. A lubricant guide is provided along components to be lubricated, such that the lubricant circuit is connected particularly effectively to the fuel supply of the internal combustion engine. A removal device for fuel with a recess which receives fuel and supplies the lubricant guide is provided between the fuel-air mixture outlet and the fuel-air mixture inlet.