A power tool includes a grinder, sander or a polisher, which has two working modes. According to an embodiment a dual power tool includes a motor operable in two operational directions, where an operational mode of the dual mode power tool is changeable by changing operational direction of the motor.

An adjustable stroke mechanism has a housing with a central axis and a wall enclosing a cavity. At least one counterweight is movably disposed within the cavity. A mounting assembly is disposed within the cavity. The mounting assembly has a workpiece attachment mechanism. A stroke adjustor couples the at least one counterweight with the mounting assembly. The stroke adjustor enables the counterweight and mounting assembly to move with respect to one another such that a distance between the counterweight and the mounting assembly is variably adjusted which, in turn, variably adjusts a stroke radius of the workpiece attachment mechanism with respect to the central axis of the housing.

An adjustable stroke mechanism has a housing with a central axis and a wall enclosing a cavity. At least one counterweight is movably disposed within the cavity. A mounting assembly is disposed within the cavity. The mounting assembly has a workpiece attachment mechanism. A stroke adjustor couples the at least one counterweight with the mounting assembly. The stroke adjustor enables the counterweight and mounting assembly to move with respect to one another such that a distance between the counterweight and the mounting assembly is variably adjusted which, in turn, variably adjusts a stroke radius of the workpiece attachment mechanism with respect to the central axis of the housing.

This document provides a method of operating a floor grinding machine 100. The method comprises providing a grinding machine 100 comprising a frame 101, a motor 102 and at least one grinding element 1, causing the motor to drive the grinding element so as to rotate at a rotational speed, while in contact with a floor surface to grind, polish or mill the floor surface, determining an actual value of a motor operating parameter, determining a nominal value of the motor operating parameter, comparing the actual value of the motor operating parameter with the nominal value of the motor operating parameter, if a difference between the actual value of the motor operating parameter and the nominal value of the motor operating parameter exceeds a predetermined difference threshold, determining at least one grinding parameter to be adjusted, and causing the at least one grinding parameter to be adjusted.

A hand-held power tool for sanding or polishing a working surface of a workpiece features a backing pad supported in respect to a housing in a manner freely rotatable about a longitudinal axis extending perpendicular to an extension plane of the backing pad. The housing or backing pad includes first magnetic elements spaced apart from each other in a direction extending parallel to the extension plane, and includes a second magnetic element located in a space between the first magnetic elements in such a manner that the second magnetic element is held at a distance to the first magnetic elements by a magnetic force when a motor of the power tool is running and the power tool is in an idle state, thereby limiting the movement of the backing pad to an orbital movement.

A hand-held power tool for sanding or polishing a working surface of a workpiece features a backing pad supported in respect to a housing in a manner freely rotatable about a longitudinal axis extending perpendicular to an extension plane of the backing pad. The housing or backing pad includes first magnetic elements spaced apart from each other in a direction extending parallel to the extension plane, and includes a second magnetic element located in a space between the first magnetic elements in such a manner that the second magnetic element is held at a distance to the first magnetic elements by a magnetic force when a motor of the power tool is running and the power tool is in an idle state, thereby limiting the movement of the backing pad to an orbital movement.

A polisher may include a polishing pad, a motor, a transmission device, and a mode selection device. The transmission device can transmit a rotational drive force of the motor to the polishing pad in a plurality of different modes with respect to a motion of the polishing pad. The mode selection device may be used for selecting a desired motion mode of the output member. Additionally, a motor and handle housing with an accompanying power cord may be constructed to aid in ease of manipulation of the polisher by the user with minimal interference.

A polisher may include a polishing pad, a motor, a transmission device, and a mode selection device. The transmission device can transmit a rotational drive force of the motor to the polishing pad in a plurality of different modes with respect to a motion of the polishing pad. The mode selection device may be used for selecting a desired motion mode of the output member. Additionally, a motor and handle housing with an accompanying power cord may be constructed to aid in ease of manipulation of the polisher by the user with minimal interference.

An adjustable stroke mechanism has a housing with a central axis and a wall enclosing a cavity. At least one counterweight is movably disposed within the cavity. A mounting assembly is disposed within the cavity. The mounting assembly has a workpiece attachment mechanism. A stroke adjustor couples the at least one counterweight with the mounting assembly. The stroke adjustor enables the counterweight and mounting assembly to move with respect to one another such that a distance between the counterweight and the mounting assembly is variably adjusted which, in turn, variably adjusts a stroke radius of the workpiece attachment mechanism with respect to the central axis of the housing.

A handheld multifunction power tool includes a driveshaft, a hub assembly, and a stem. The hub assembly includes an outer hub and an inner hub that is rotatably coupled with the inner hub and rotatable with respect to the outer hub. Rotation of the inner hub relative to the outer hub facilitates selection from among a rotary mode and a random orbital mode.