Abstract: The invention relates to an auto tensioner of a chain saw. A spiral guide groove (16) of the disk (15) engages with a protrusion 10a of a slider piece (10) and the slider piece (10) is slidably stored in a guide portion (9) formed in a chain cover (2) via a spring (14). A tensioner (11) comprising a protrusion (11) engaged with a guide bar is slidably stored in the slider piece 10 via a coin spring (12). The protrusion (10a) contacts an outer circumference face of the spiral guide groove on a diameter passing through a rotating center of the disk, and an unshown nut for engaging with a stud bolt 6 provided on an engine cover side is attached on the rotating center of the disk (15). A rotation of the disk enables to fix the chain cover (2) and move the guide bar.

Abstract: A chain saw includes a body in which an engine for driving a saw chain is laterally housed; a top handle provided above the body; and a muffler arranged below the engine, in which an exhaust outlet for discharging exhaust from the body side to the outside opens forward from the body side. Accordingly, not only the exhaust can be discharged forward from the side of the body, but also the exhaust sound can be propagated forward so that less exhaust sound is heard by the operator, thereby improving the work environment.

Abstract: A chain saw has a body in which a stratified scavenging 2-cycle engine for driving a saw chain is laterally housed and a top handle provided above the body. In other words, by laterally disposing the engine, an air port can be installed upward to a cylinder, and an air quantity adjusting device for feeding scavenging air to the air port and the carburetor can be well housed in the top handle. Accordingly, there is no need to separately prepare a space for installing the air quantity adjusting device, so that miniaturization can be achieved.

Abstract: A transmissible connecting mechanism having a cam plate and a lever are attached respectively to a lead air control valve shaft and an air-fuel mixture throttle valve shaft which are arranged so as to form an angle. A length of a contact element provided in the lever is extended in parallel to an axis of the air-fuel mixture throttle valve shaft, and the length of the contact element is such that the contact element and a cam surface formed in a cam plate are always brought into contact with each other. The lead air control valve shaft and the air-fuel mixture throttle valve shaft of the carburetor are connected in a transmissible manner, and it is possible to make a stratified scavenging two-cycle engine compact.

Abstract: An engine start device having a first start mode in which the engine is started on a spot by executing a start operation of the engine, and a second start mode in which a necessary accumulated force is previously accumulated in to start in one time in an optional place at an optional timing. In the first start mode, an accumulated force, accumulated by a rotation of a rotation drive section allows the engine to be started on the spot. If switched to the second start mode, the rotation of the rotation drive section is exclusively accumulated and released in the optional place at a desired time so as to start the engine in accordance with a one-touch operation.

Abstract: An electric engine starter in which downsizing and weight saving are improved to an extreme based on the rational design and by eliminating an unnecessary unit, wherein a battery is arranged outside the starter, a power accumulating unit has a rotation supporting unit for supporting one end of a spring, a first gear is formed on the rotation supporting unit, a second gear is fixed to an output shaft of a high-speed reduction gear mechanism, the first and the second gears are engaged with each other, the power accumulating unit and the power transmission unit are arranged on the same first axis line, the compact electric motor and the high-speed reduction gear mechanism are arranged on the same second axis line parallel to the first axis line, and the first axis line and the second axis line are arranged on the same plane surface.