An electrical hammer (100) comprises a main housing (101), a hand grip (500) connected to the main housing (101) via a compression coil spring (321). In the electrical hammer (100), a hammer bit (119) is driven by a first motion converting mechanism (120) and thereby a hammering operation is performed. During the hammering operation, the hand grip (500) is moved against the main housing (101) in a state that biasing force of the compression coil spring (321) is applied on the hand grip (500). Further, the electrical hammer (100) comprises a second motion converting mechanism (220) which drives a counterweight (231).

A machine tool and control method are disclosed. The machine tool has a tool receptacle which supports a chiseling tool so that it is movable along an axis of movement. A magneto-pneumatic striking mechanism has a primary drive, which is arranged around the axis of movement, and has a first magnetic coil and a second magnetic coil. On the axis of movement within the magnetic coils, the striking mechanism has a striker and riveting head. Furthermore, the striking mechanism has a pneumatic spring which acts on the striker. The control method provides for a pressure sensor which measures the prevailing pressure in the pneumatic spring during a movement of the striker in the direction opposite the striking direction. A controller initiates an acceleration phase at the start of a drop in pressure in the pneumatic spring. The primary drive accelerates the striker in the striking direction during the acceleration phase.

A machine tool and control method are disclosed. The machine tool has a tool receptacle which supports a chiseling tool so that it is movable along an axis of movement. A magneto-pneumatic striking mechanism has a primary drive, which is arranged around the axis of movement, and has a first magnetic coil and a second magnetic coil. On the axis of movement within the magnetic coils, the striking mechanism has a striker and riveting head. Furthermore, the striking mechanism has a pneumatic spring which acts on the striker. The control method provides for a pressure sensor which measures the prevailing pressure in the pneumatic spring during a movement of the striker in the direction opposite the striking direction. A controller initiates an acceleration phase at the start of a drop in pressure in the pneumatic spring. The primary drive accelerates the striker in the striking direction during the acceleration phase.

In order to provide an impact tool which is capable of increasing a striking force in a rotational direction of being applied from a hammer to an anvil, the impact tool includes: an electric motor; an anvil which supports a work tool and is driven by the electric motor; and a hammer which applies the striking force in the rotational direction to the anvil. The impact tool is provided with: a spindle which is arranged to be concentric with the anvil, supports the hammer to be movable in an axial direction and the rotational direction with respect to the anvil, and transmits motive power of the electric motor to the anvil; and a control unit which controls rotation speed of the electric motor. The number of strokes of the anvil due to one rotation of the hammer differs in response to rotation speed of the electric motor.

In order to provide an impact tool which is capable of increasing a striking force in a rotational direction of being applied from a hammer to an anvil, the impact tool includes: an electric motor; an anvil which supports a work tool and is driven by the electric motor; and a hammer which applies the striking force in the rotational direction to the anvil. The impact tool is provided with: a spindle which is arranged to be concentric with the anvil, supports the hammer to be movable in an axial direction and the rotational direction with respect to the anvil, and transmits motive power of the electric motor to the anvil; and a control unit which controls rotation speed of the electric motor. The number of strokes of the anvil due to one rotation of the hammer differs in response to rotation speed of the electric motor.

An impact tool is provided which has a driving mechanism 120, 140 that drives a tool bit 119, a motor 110 that drives the driving mechanism 120, 140, an inner housing 103 that houses the driving mechanism 120, 140, an outer housing 101 that has an internal space for housing the inner housing 103 and the motor 110, an opening 193 that leads from the outside to the internal space of the outer housing 101, and a covering member 195 that covers the opening 193.

It is an object of the invention to provide an impact tool having a rational mechanism in an idling state. According to the representative invention, in an idling state defined as a state in which a tool accessory 119 is not pressed against a workpiece and an impact bolt 145 transmits a striking force to the tool accessory 119, the tool accessory retainer 510 moves with respect to a tool accessory holder 117 by movement of the tool accessory 119 in the longitudinal direction, so that the striking force is cushioned.

It is an object of the invention to provide an impact tool having a rational mechanism in an idling state. According to the representative invention, in an idling state defined as a state in which a tool accessory 119 is not pressed against a workpiece and an impact bolt 145 transmits a striking force to the tool accessory 119, the tool accessory retainer 510 moves with respect to a tool accessory holder 117 by movement of the tool accessory 119 in the longitudinal direction, so that the striking force is cushioned.

A hammer drill includes a boss sleeve rotatably and externally mounted to an intermediate shaft separately from the intermediate shaft. The boss sleeve includes a rod coupled to a rear end of a piston cylinder via a swash bearing. The boss sleeve is configured to rotate to convert a rotation of the intermediate shaft into a reciprocating motion in a front-rear direction of the rod and transmit the reciprocating motion to the piston cylinder. The hammer drill includes a second clutch disposed at the intermediate shaft. By performing a switch operation of a slide position of the second clutch, a hammer mode in which the second clutch is engaged with the boss sleeve to reciprocate the piston cylinder back and forth and another operation mode are selectable. The boss sleeve is rotatably cantilevered not to be in contact with the intermediate shaft by an inner housing via a bearing.

A hammer drill includes a boss sleeve rotatably and externally mounted to an intermediate shaft separately from the intermediate shaft. The boss sleeve includes a rod coupled to a rear end of a piston cylinder via a swash bearing. The boss sleeve is configured to rotate to convert a rotation of the intermediate shaft into a reciprocating motion in a front-rear direction of the rod and transmit the reciprocating motion to the piston cylinder. The hammer drill includes a second clutch disposed at the intermediate shaft. By performing a switch operation of a slide position of the second clutch, a hammer mode in which the second clutch is engaged with the boss sleeve to reciprocate the piston cylinder back and forth and another operation mode are selectable. The boss sleeve is rotatably cantilevered not to be in contact with the intermediate shaft by an inner housing via a bearing.