Abstract: A power unit for portable chain saws wherein an ignition coil is placed at a position so as to increase both the compactness and the cooling efficiency of the power unit. A coil support on which the ignition coil is supported is formed integratedly with a crank case; adjacent to an open port; and on a part of an external periphery of the flywheel, said second part being not enclosed by the air-guiding passage. The coil support extends from the crank case along a side of a muffler and forms an insulating gap from the muffler.

Abstract: A power unit for portable chain saws wherein an ignition coil is placed at a position so as to increase both the compactness and the cooling efficiency of the power unit. A coil support on which the ignition coil is supported is formed integratedly with a crank case; adjacent to an open port; and on a part of an external periphery of the flywheel, said second part being not enclosed by the air-guiding passage. The coil support extends from the crank case along a side of a muffler and forms an insulating gap from the muffler.

Abstract: A brake system of a working machine includes a brake connector for operatively connecting between a brake lever and a braking member, and an urging member that maintains the brake lever at a predetermined neutral position and also acts to return the brake lever to the predetermined neutral position when the brake lever is displaced from the predetermined neutral position. When the brake lever is located at the predetermined neutral position, the brake lever and the brake connector are out of contact with each other.

Abstract: There is provided a portable power working machine, which is capable of rationally and effectively preventing the generation of the icing without giving rise to early clogging of air cleaner, the malfunction of a internal combustion engine and deterioration of performance. This working machine comprises a small air-cooled internal combustion engine which is mounted inside a main housing, a cooling fan disposed on one side of the main housing; a carburetor coupled to an upper portion of an intake port of the internal combustion engine; a clean air chamber disposed on an upstream side of the carburetor; an air cleaner cover coupled to the clean air chamber; a warm air introducing passageway for introducing, through a region adjacent to the intake port, part of air which has been sucked by the cooling fan for cooling the internal combustion engine into the air cleaner cover; and a shutter for and externally opening or closing the warm air introducing passageway as desired.

Abstract: A chain saw with vibration-isolating devices, capable of providing a desirable vibration-isolating effect over a wide frequency range and reducing accidental deviation from a desired cutting line in a cutting operation. The chain saw includes a main body containing an engine, a frame member mounting a grip handle thereon, and at least two vibration-isolating devices each interposed between the main body and the frame member to support the main body with respect to the frame member. Two of the vibration-isolating devices are disposed spaced apart from each other in the longitudinal direction of the chain saw. Each of the two vibration-isolating devises includes a pair of first and second vibration=isolating members which are different in frequency range for providing a vibration-isolating effect. The two vibration-isolating devices are disposed such that the respective first or second vibration-isolating members are positioned in a first or second diagonal relationship with respect to one another.

Abstract: There is provided a portable power working machine, which is capable of rationally and effectively preventing the generation of the icing without giving rise to early clogging of air cleaner, the malfunction of a internal combustion engine and deterioration of performance. This working machine comprises a small air-cooled internal combustion engine which is mounted inside a main housing, a cooling fan disposed on one side of the main housing; a carburetor coupled to an upper portion of an intake port of the internal combustion engine; a clean air chamber disposed on an upstream side of the carburetor; an air cleaner cover coupled to the clean air chamber; a warm air introducing passageway for introducing, through a region adjacent to the intake port, part of air which has been sucked by the cooling fan for cooling the internal combustion engine into the air cleaner cover; and a shutter for and externally opening or closing the warm air introducing passageway as desired.

Abstract: The present invention provides a chain saw having a high degree of safety for its various positions including an upward and a downward position. The chain saw comprises a bar-shaped top handle extending in a lengthwise direction above an upper surface of a main body and a bar-shaped side handle provided next to a left side surface of the main body. When the main body is seen in a plan view, a front end portion of the side handle is intersected transversely with and coupled to a left side surface of a front end portion of the top handle. A right-side support surface extending outwardly in the transverse direction is provided on a right side surface of the front end portion of the top handle. It is located substantially at the same position as a left-side support surface which is comprised of a rear surface of the front end portion of the side handle in the lengthwise direction of the main body.

Abstract: A chain saw with vibration-isolating devices, capable of providing a desirable vibration-isolating effect over a wide frequency range and reducing accidental deviation from a desired cutting line in cutting operation. The chain saw includes a main body containing an internal combustion engine which has a crankshaft extending in the lateral direction of the chain saw, a saw chain extending from the main body in the forward direction of the chain saw, a frame member mounting a grip handle thereon, and at least two vibration-isolating devices each interposed between the main body and the frame member to support the main body with respect to the frame member. Two of the vibration-isolating devices are disposed spaced apart from each other in the longitudinal direction of the chain saw. Each of the two vibration-isolating devices includes a pair of first and second vibration-isolating members which are different in frequency range for providing a vibration-isolating effect.