An alternating current power tool includes a function element, a brushless motor, and a motor control circuit. The motor control circuit includes a power module, a first rectifier circuit, a driver circuit, a controller, and a second rectifier circuit. The power module is used for receiving an alternating current. The first rectifier circuit is used for receiving the alternating current received by the power module and operatively outputting a direct current bus voltage. The second rectifier circuit is electrically connected to the power module and used for receiving the alternating current received and outputting a direct current to supply power to at least the controller.

A machine tool deceleration device, in particular a hand-held machine tool deceleration device, for a portable machine tool, includes at least one magnetic deceleration unit. The magnetic deceleration unit includes at least one movably mounted claw segment element that is configured to change at least one parameter of a magnetic field of the magnetic deceleration unit.

A stop lever is provided for a power tool having a gear case and a guard member. The reversible stop lever is coupled to the gear case via a fastener. The stop lever includes a first arm and a second arm, and the fastener is removable to position the stop lever such that the first arm or the second arm of the stop lever engages the guard collar. The first arm includes a first surface and a second surface that are angled such that the guard collar can be rotated in a one direction without actuation of the second arm, but not in the opposite direction. The second arm of the stop lever includes surfaces that are angled to prevent rotation of the guard collar in either direction unless the second arm is actuated about the fastener.

The present invention relates to a device for detaching/attaching a hand grinder polishing disk, the device being clamped on the rotating shaft of a grinder main body so as to enable the easier and quicker detachment/attachment of a consumable polishing disk used for finishing, cutting, severing, etc. the surface of a target object, or to enable the definite prevention of loosening, vibration phenomenon, etc. The present invention comprises: a grinder main body which has a rotating shaft operating at a high speed by means of air pressure or the driving of an electric motor; a power transmission member which has a stopping protrusion formed on the upper end part of the body thereof and a hexagonal body including a flange formed on the center part of the body thereof, and which is clamped on the rotating shaft of the grinder main body by a fixing bolt; a stopper main body which has a hexagonal hole formed on the inner circumferential surface thereof for accommodating the power transmission member, and which has an arc-shaped seat groove formed on the circumference of the hexagonal hole so as to face each other; a pair of upper and lower rotating plates which are each fitted in a flat plate portion on the upper end of the stopper main body; and a disk holder which has an upper fixing ring and a lower support plate assembled on the power transmission member for fixing an abrasive material.

Provided is an easy-to-use electric tool with which braking force can be changed according to work conditions. When an operation switch 5 is turned off, a control unit 50 detects a rotation rate R1 of an electric motor 6. The control unit 50 stands by for a prescribed period, detects a rotation rate R2 of the electric motor 6, and calculates the difference between the rotation rates R1, R2 (R=R1−R2). Since the rotation rate difference R corresponds to the rate of change in rotation rate with time during deceleration of the electric motor 6 and is smaller the larger the moment of inertia of the attached rotary tool, the control unit 50 can determine the moment of inertia of the rotary tool on the basis of the rotation rate difference R. The control unit 50 sets the braking force according to the moment of inertia and performs braking.

A handheld AC power tool is provided. The power tool is comprised generally of: a brushless DC motor; a power cord connectable to an AC power socket; a converter circuit configured to receive input power from the power cord and operable to output a DC bus voltage, a switching arrangement interposed between the electric motor and the converter circuit; a motor drive circuit interfaced with the motor switches; and a power switch operable by a user to selectively energize the motor drive circuit and thereby power on the tool. The converter circuit includes a rectifier and a capacitor electrically coupled across the rectifier, such that the capacitor has capacitance sized to produce a DC bus voltage whose magnitude from an AC power source is substantially same as magnitude of voltage from a DC power source.

A rotary tool includes simple wiring from the controller. A grinder includes a housing, a motor accommodated in the housing, a final output shaft accommodated in the housing to receive a tip tool and rotatable by the motor being driven, and a plurality of controllers accommodated in the housing. The plurality of controllers include at least a first controller receiving an electrical component of the grinder on an outer surface of the first controller. The electrical component performs an electrical operation.

Vibrations and a reaction force transferred to an operator are effectively reduced to improve usability and operability. A grinder includes an inner housing accommodating a motor, a final output shaft located in front of the motor, a connecting shaft parallel to the final output shaft, a front elastic member located in front of the connecting shaft, and an outer housing enclosing the inner housing and holding, with the connecting shaft and the front elastic member in between, the inner housing in a relatively rotatable manner.

A power tool, in particular an angle grinder, having a drive motor accommodated in a housing which drives a rotor shaft, a tool spindle comprising a tool holder which is preferentially connected to the rotor shaft in a power-transmitting manner by a gearing, as well as a control switch for activating the drive motor, wherein the control switch comprises a first switching element which is pivotably mounted on the housing about a pivot axis between a first switch position for switching on the drive motor and a second switch position for switching off the drive motor, and a second switching element which is rotatable about a rotational axis between a locked position which blocks the first switching element from moving into the first switch position and a release position which enables the first switching element to move into the first switch position.

A protection device for a power tool is provided. The power tool can be, in particular, a hand-held battery-operated power tool, such as a cut-off grinder. The power tool preferably has main components in a main region, such as a motor, transmission and rechargeable batteries, which are protected effectively from mechanical damage, e.g. when dropped, by the protection device. Moreover, the protection device prevents the transmission of vibrations in the power tool to the user. In a second aspect, the invention relates to a system which comprises a protection device and a power tool.