A handheld power tool 1 has a tool socket 2 to hold a tool along a working axis 11. A motor-driven, pneumatic striking mechanism 6 has an exciter 17 which is driven by a motor 5, a striker 14 that is coupled to the exciter 17 via a pneumatic chamber 19, and an intermediate striker 22 arranged on the working axis 11 in the striking direction 12 behind the striker 14. A ventilation opening 30 connects a cavity 29 situated between the striker 14 and the intermediate striker 22 to the environment. A valve 38 that closes the ventilation opening 30 is opened when actuated by the intermediate striker 22 when the intermediate striker 22 is moved into its working position counter to the striking direction 12.

A striking tool restricting movement of an intermediate member toward a striker reliably prevents no-load strokes. A hammer drill includes a cylindrical tool holder holding a tip tool, a motor, a piston that reciprocate with rotation from the motor, a striker that reciprocate in cooperation with the piston, an intermediate member reciprocably accommodated in the tool holder between the striker and the tip tool and in contact with a rear end of the tip tool at a normal strike to indirectly transmit a strike from the striker to the tip tool, and at least two ring members that move in a front-rear direction accommodated in the tool holder at a front of the intermediate member between the tool holder and the intermediate member. At least one ring member is made of metal.

A hammer drill is provided with a hammer mechanism that includes a cylinder having a central axis, a ram having a radial recess slidably mounted within the cylinder, a piston slidably mounted within the cylinder, and a ram catcher. The ram catcher includes a first ring and a second ring surrounding the central axis and forming a groove therebetween, the second ring being located between the first ring and the end of the cylinder. An O-ring that is resiliently-deformable is mounted within the groove and includes an inner side projecting inwardly towards the central axis. When the ram is in a working position, the O-ring is located forward of the ram. When the ram is in a forward position, the O-ring is located in-line with the radial recess of the ram.

The invention relates to a striking hand-held machine tool having a tool holder for holding a striking tool on a working shaft, an electric motor, and a striking mechanism. In the striking direction, the striking mechanism has an exciter piston, a pneumatic chamber, a striker, an intermediate chamber and a rivet snap following one another. A closed channel connects a first channel opening in the pneumatic chamber and a second channel opening in the intermediate chamber. A non-return valve, which shuts off during an air flow from the first channel opening to the second channel opening and opens during an air flow from the second channel opening to the first channel opening, is arranged in the channel. Arranged on the second channel opening is a shut-off valve, which is forced into a position closing the second channel opening when the rivet snap is in the working position.

A hammer drill having a motor mounted within a body and an output spindle; a tool holder mounted on the body capable of holding a cutting tool; a hammer mechanism having a piston; a reciprocating drive for converting rotary movement of the motor into reciprocating movement of the piston; a ram reciprocatingly driven by the piston via an air spring to strike a cutting tool held in the tool holder, the hammer mechanism performing one hammer cycle each time the ram strikes a cutting tool during normal use; an air replenishment mechanism capable of refreshing the air spring during certain time periods during normal use; the air replenishment mechanism capable of being adjusted to refresh the air spring during time periods within the hammer cycle and/or the system allows different volumes of air into or out of the air spring during the refreshment time periods.

A handheld power tool 1 has a tool socket 2 to hold a tool along a working axis 11. A motor-driven, pneumatic striking mechanism 6 has an exciter 17 which is driven by a motor 5, a striker 14 that is coupled to the exciter 17 via a pneumatic chamber 19, and an intermediate striker 22 arranged on the working axis 11 in the striking direction 12 behind the striker 14. A ventilation opening 30 connects a cavity 29 situated between the striker 14 and the intermediate striker 22 to the environment. A valve 38 that closes the ventilation opening 30 is opened when actuated by the intermediate striker 22 when the intermediate striker 22 is moved into its working position counter to the striking direction 12.

A machine tool is disclosed. A magneto-pneumatic striking mechanism has a primary actuator arranged around an axis of movement and includes a first magnetic coil and a second magnetic coil. The striking mechanism has, on the axis of movement within the magnetic coils, a striker and a die. Furthermore, the striking mechanism has an air spring acting on the striker in a direction of impact. The air spring may be entirely or partially within the first magnetic coil. The air spring has a ventilation opening that is open to the environment if the striker is less than 10% of its stroke away from the die, and otherwise the ventilation opening is closed. An exchange of air with the environment is therefore only possible when the striker is near the die or is near the impact position.

A rotary hammer adapted to impart axial impacts to a tool bit. The rotary hammer includes a housing, a motor supported by the housing, a spindle coupled to the motor for receiving torque from the motor, causing the spindle to rotate, a reciprocation mechanism operable to create a variable pressure air spring within the spindle, an anvil received within the spindle for reciprocation in response to the pressure of the air spring, the anvil imparting axial impacts to the tool bit, a bit retention assembly for securing the tool bit to the spindle, and an electromagnetic clutch mechanism switchable between a first state, in which the reciprocation mechanism is enabled, such that the anvil imparts axial impacts to the tool bit, and a second state, in which the reciprocation mechanism is disabled, such that the anvil ceases to impart axial impacts to the tool bit.

The control method for a hammer drill (1) provides the following steps. During basic operation, the motor (5) rotates at an operating speed for the drilling operation with chiseling action in order to rotationally drive the tool holder (2) and to drive the hammer mechanism (6) with a nominal striking power. The torque coupling (21) is monitored with the aid of a sensor (26). If a disengagement of the torque coupling (21) occurs, the striking power of the hammer mechanism (6) is reduced to below 10% of the nominal striking power during a disengagement of the torque coupling (21), and the torque coupling (21) is driven. When the disengagement of the torque coupling (21) ends, the striking power of the hammer mechanism (6) is increased to the nominal striking power and the torque coupling (21) is driven at the operating speed for the drilling operation with chiseling action.

Percussion unit, especially for a rotary hammer and/or percussion hammer, comprising a control unit which is designed for controlling a pneumatic percussion mechanism. According to the disclosure, the control unit comprises at least one load estimation device.