A work apparatus has a work tool driven by a combustion engine. A brake assembly has a brake element for braking the work tool as it slows down. In a braking position of the brake assembly, the work tool is braked, while, in a stand-by position of the brake assembly, the brake element enables the movement of the work tool. The brake element is held in the stand-by position by a holding force from an electromagnet supplied with energy by an electric generator driven by the engine, for which purpose, in the stand-by position of the brake assembly, a holding current is supplied to the electromagnet. To extend the holding time as the engine slows down, an operating parameter of the engine is monitored and, after a limit value of the operating parameter is reached, the holding current supplied to the electromagnet is reduced.

A motor able to prevent axial displacement of a rotor in a simple structure without increasing the number of parts of the motor. The motor includes a rotor including a shaft, a housing configured to support the shaft rotatably and movably in a limited manner in an axial direction, a flange disposed on an axially outside of the housing and configured to rotate integrally with the shaft, the flange projecting radially outward from the shaft and being configured to prevent a foreign object from entering the housing, and a temporary tacking structure provided in at least one of the flange and the housing, and configured to temporarily tack the housing and the flange to each other in the axial direction.

The tool holding device includes: a casing including a first surface, a second surface opposed to the first surface, and a first projection and a second projection projecting opposite to the first surface from the second surface; a first tool holding part disposed on the first surface at a position opposed to the first projection; a second tool holding part disposed on the first surface at a position opposed to the second projection; a driving-force input unit disposed at the end of the first projection and rotated by driving force being inputted; a first shaft extending in an axial direction perpendicular to the first surface and the second surface, the driving-force input unit and the first tool holding part being disposed at one end and the other end of the first shaft, respectively; a second shaft extending in the axial direction and having one end housed in the second projection, the second tool holding part being disposed at the other end of the second shaft; and a rotation transmitting unit rotating the second shaft in response to rotation of the first shaft.

A spindle device includes: a spindle housing; a spindle shaft configured to be rotatably supported inside the spindle housing; a spindle mount having an insertion cavity into which the spindle housing is inserted along the axial direction of the spindle shaft; a flange portion projecting outward from the outer peripheral surface of the spindle housing and configured to be removably fixed to an end of the spindle mount that is closer to one opening of the insertion cavity; and a support member configured to support the spindle housing inserted in the insertion cavity by using, as a base, the other end of the spindle mount that is closer to the other opening of the insertion cavity.

A spindle device includes: a spindle housing; a spindle shaft configured to be rotatably supported inside the spindle housing; a spindle mount having an insertion cavity into which the spindle housing is inserted along the axial direction of the spindle shaft; a flange portion projecting outward from the outer peripheral surface of the spindle housing and configured to be removably fixed to an end of the spindle mount that is closer to one opening of the insertion cavity; and a support member configured to support the spindle housing inserted in the insertion cavity by using, as a base, the other end of the spindle mount that is closer to the other opening of the insertion cavity.

A turret tool rest includes a main shaft, a turret turning shaft, a turret, a joint base, a mill housing connection shaft, and an engagement member. The main shaft rotates a tool. A part of the main shaft is provided in the turret turning shaft. The turret turning shaft has a first coupling hole. The turret is connected to the turret turning shaft via which the turret is rotated. The joint base has a second coupling hole. The mill housing connection shaft is connected to the joint base. The mill housing connection shaft is provided between the main shaft and the turret turning shaft. Each of the mill housing connection shaft, the joint base, the part of the main shaft, and the turret turning shaft are disposed to rotate around a rotation axis of the turret. The engagement member moves in the first coupling hole and the second coupling hole.

A turret tool rest includes a main shaft, a turret turning shaft, a turret, a joint base, a mill housing connection shaft, and an engagement member. The main shaft rotates a tool. A part of the main shaft is provided in the turret turning shaft. The turret turning shaft has a first coupling hole. The turret is connected to the turret turning shaft via which the turret is rotated. The joint base has a second coupling hole. The mill housing connection shaft is connected to the joint base. The mill housing connection shaft is provided between the main shaft and the turret turning shaft. Each of the mill housing connection shaft, the joint base, the part of the main shaft, and the turret turning shaft are disposed to rotate around a rotation axis of the turret. The engagement member moves in the first coupling hole and the second coupling hole.

An object is to provide a machine-tool spindle cooling method and a machine tool capable of suppressing thermal deformation of a spindle while achieving energy saving. To achieve it, a machine-tool spindle cooling method is provided in which bearings (13) and a spindle rotation motor (14) that generate heat with rotation of a spindle (12) are cooled by causing a spindle cooling device (18) to supply and circulate cooled cooling oil inside a housing (11) rotatably supporting the spindle (12), the method comprising deactuating the spindle cooling device (18) to thereby stop supplying the cooling oil in a case where the number of revolutions of the spindle (12) is less than or equal to a predetermined number of revolutions and the temperatures of the bearings (13) and the spindle rotation motor (14) detected by temperature sensors (15, 16) are less than or equal to a predetermined temperature.

An object is to provide a machine-tool spindle cooling method and a machine tool capable of suppressing thermal deformation of a spindle while achieving energy saving. To achieve it, a machine-tool spindle cooling method is provided in which bearings (13) and a spindle rotation motor (14) that generate heat with rotation of a spindle (12) are cooled by causing a spindle cooling device (18) to supply and circulate cooled cooling oil inside a housing (11) rotatably supporting the spindle (12), the method comprising deactuating the spindle cooling device (18) to thereby stop supplying the cooling oil in a case where the number of revolutions of the spindle (12) is less than or equal to a predetermined number of revolutions and the temperatures of the bearings (13) and the spindle rotation motor (14) detected by temperature sensors (15, 16) are less than or equal to a predetermined temperature.

A drive unit with a spindle drive and a spindle-drive drive motor, which comprises a rotor, is characterized in that a spindle of the spindle drive is arranged inside the rotor acting as a spindle nut and comprising a hollow shaft. As a result, a particularly compact construction for the drive unit can be realized, which can serve, in particular, as a linear drive of tool sleeve.