A resin gear includes an annular metal bush, an annular resin member provided around the metal bush and having a tooth profile formed in an outer peripheral portion, and an elastic member provided between the metal bush and the resin member. The elastic member has a first overhanging portion overhanging one end surface of the metal bush and one end surface of the resin member outward in an axial direction of the resin gear.

A resin gear includes an annular metal bush and an annular resin member provided around the metal bush. The metal bush and the resin member are disposed so as to be relatively rotatable in a direction of rotation of the resin gear. A plurality of spaces entering an outer peripheral surface of the metal bush and an inner peripheral surface of the resin member are formed, so as to be aligned along the direction of rotation, between the metal bush and the resin member. The space has, in at least one end portion in an axial direction of the resin gear, inner surfaces intersecting with the axial direction. An elastic member is disposed in the space. The elastic member engages with the inner surfaces.

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.

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.

An electromotive actuator to adjust a height includes an electric motor with a motor shaft, a helical gear assembly operatively connected to the motor shaft, a sleeve-shaped friction brake to act on the motor shaft, and a housing surrounding the electric motor or the helical gear assembly and including a seat of the friction brake. The friction brake includes an opening extending in a radial direction relative to a longitudinal axis of the motor shaft such that the friction brake is attachable to the motor shaft perpendicular to the longitudinal axis.

An electromotive actuator to adjust a height includes an electric motor with a motor shaft, a helical gear assembly operatively connected to the motor shaft, a sleeve-shaped friction brake to act on the motor shaft, and a housing surrounding the electric motor or the helical gear assembly and including a seat of the friction brake. The friction brake includes an opening extending in a radial direction relative to a longitudinal axis of the motor shaft such that the friction brake is attachable to the motor shaft perpendicular to the longitudinal axis.

A gear includes a tubular portion and a diaphragm portion. The diaphragm portion extends in a direction including a radial component from one axial end portion of the tubular portion. The portion includes a first portion and a second portion. The first portion is on one axial side of the portion. The second portion is on another axial side relative to the first portion. The second portion includes teeth protruding radially outward. A maximum value of a thickness of the diaphragm portion is equal to or less than twice a distance from radially outer ends of the teeth to a radially inner surface of the second portion, and a minimum value of a thickness of the first portion is equal to or less than half the maximum value of the thickness of the diaphragm portion.

A gear includes a tubular portion and a diaphragm portion. The diaphragm portion extends in a direction including a radial component from one axial end portion of the tubular portion. The portion includes a first portion and a second portion. The first portion is on one axial side of the portion. The second portion is on another axial side relative to the first portion. The second portion includes teeth protruding radially outward. A maximum value of a thickness of the diaphragm portion is equal to or less than twice a distance from radially outer ends of the teeth to a radially inner surface of the second portion, and a minimum value of a thickness of the first portion is equal to or less than half the maximum value of the thickness of the diaphragm portion.

Gear devices and methods for operating gear devices are provided. In one example, a gear device is provided that comprises structures designed to attenuate targeted vibrations occurring during rotation of the gear device. The structures includes radially aligned struts extending between an inner carrier and an outer carrier, a plurality of openings arranged between the struts, and/or resonators extending between sequential struts.

Gear devices and methods for operating gear devices are provided. In one example, a gear device is provided that comprises structures designed to attenuate targeted vibrations occurring during rotation of the gear device. The structures includes radially aligned struts extending between an inner carrier and an outer carrier, a plurality of openings arranged between the struts, and/or resonators extending between sequential struts.