Abstract: A power tool has a motor having a rotary shaft, an eccentric shaft configured to be rotated around a rotation center axis of the rotary shaft, and a balancer configured to rotate with the rotary shaft. When viewed along the rotation center axis, (1) a first imaginary line passes the rotation center axis and an eccentric axis, (2) an imaginary perpendicular line crosses perpendicularly to the first imaginary line and passes the rotation center axis, (3) a center of gravity of the balancer is located in a region on a side opposite to the eccentric axis across the imaginary perpendicular line; and (4) a second imaginary line passes the rotation center axis and the center of gravity of the balancer and (5) the second imaginary is inclined at an inclination angle larger than 0° and smaller than 90° in a direction opposite to a rotating direction of the rotary shaft.

Abstract: A power tool such as a portable cutting machine has less gear noise from, for example, a reduction gear train under no load. The power tool includes a blade, an electric motor including a motor shaft, and a gear train that transmits a rotational output from the electric motor to the blade. The gear train includes a first gear supported on the motor shaft, a countershaft, an intermediate gear meshing with the first gear and supported on the countershaft, a final shaft having a distal end attached to the blade, a final gear meshing with the intermediate gear and supported on the final shaft, and at least one elastic member between the final shaft and the final gear.

Abstract: A power tool has a motor having a rotary shaft, an eccentric shaft configured to be rotated around a rotation center axis of the rotary shaft, and a balancer configured to rotate with the rotary shaft. When viewed along the rotation center axis, (1) a first imaginary line passes the rotation center axis and an eccentric axis, (2) an imaginary perpendicular line crosses perpendicularly to the first imaginary line and passes the rotation center axis, (3) a center of gravity of the balancer is located in a region on a side opposite to the eccentric axis across the imaginary perpendicular line; and (4) a second imaginary line passes the rotation center axis and the center of gravity of the balancer and (5) the second imaginary is inclined at an inclination angle larger than 0° and smaller than 90° in a direction opposite to a rotating direction of the rotary shaft.

Abstract: A power tool such as a portable cutting machine has less gear noise from, for example, a reduction gear train under no load. The power tool includes a blade, an electric motor including a motor shaft, and a gear train that transmits a rotational output from the electric motor to the blade. The gear train includes a first gear supported on the motor shaft, a countershaft, an intermediate gear meshing with the first gear and supported on the countershaft, a final shaft having a distal end attached to the blade, a final gear meshing with the intermediate gear and supported on the final shaft, and at least one elastic member between the final shaft and the final gear.

Abstract: A feed mechanism is constructed with a piezoelectric actuator embedded in the front end of a square sliding shaft, which is supported by hydrostatic guide surfaces formed on a guide base for sliding motion in the axial direction. A cooling jacket having a helical channel on its outside surface is provided at the periphery of the piezoelectric actuator. A part of pressurized fluid fed to the hydrostatic guide surfaces is led to the helical channel of the cooling jacket through a cooling oil feeding channel formed in the sliding shaft, and fluid in the helical channel is drained to a low pressure space through an oil discharging channel formed in the sliding shaft.

Abstract: A hydrostatically supporting device for slide wherein a first slide member is provided with four guide surfaces constituting a square guide bore, and a second slide member having a square cross section is mated with the first slide member for sliding movements therebetween. Each of guide surfaces is provided with a pair of hydrostatic supporting surfaces formed at longitudinal ends of the guide surfaces, respectively, and each hydrostatic supporting surface is formed with a first hydrostatic pressure pocket formed at lateral center of the hydrostatic supporting surface and extending in the sliding direction. This first hydrostatic pressure pocket is provided with an oil supplying nozzle for supplying pressurized oil therethrough.

Abstract: A slide guided on a guiding member has at least one sliding surface in slidable engagement with a guiding surface of the guiding member. The at least one sliding surface is formed with an elongate supply grove extending in the sliding direction of the slide and is also formed with a plurality of hydrostatic pressure pockets arranged in the sliding direction of the slide. The slide is formed therein with passages which respectively provide fluid communications of the hydrostatic pressure pockets with the elongate supply groove, and a plurality of throttle elements are respectively fitted in the passages at portions of the same opening to the hydrostatic pressure pockets. A supply passage connected to an oil supply is formed in the guiding member and at the guiding surface, opens to the elongate supply groove for always communicating with the elongate supply groove irrespective of the sliding position of the slide.