An electric power tool has a brushless motor for driving a tip tool, and a motor case is at least partly covered by a motor housing made of aluminum alloy and exposed to an outside. A control board provided with a control circuit for controlling the rotation of the brushless motor is disposed adjacent to the motor housing. The brushless motor and a control board are cooled by cooling air generated by a fun, thereby enhancing the cooling characteristics of the motor control circuit.

A hammer drive mechanism for a hammer strike mechanism of a hammer drill is provided including: a drive shaft capable of being rotationally driven by a motor, a rod capable of reciprocatingly driving a piston, and a conversion mechanism that converts the rotary movement of the drive shaft into a reciprocating movement of the rod. The drive shaft comprises a first part connected to the conversion mechanism and a second part capable of being rotationally driven by a motor. The second part connects to the first part via at least one dampener such that rotary movement of the second part is transferred to the first part via the at least one dampener.

A work tool includes a driving motor, a rotary shaft member configured to be rotationally driven by the driving motor, a swinging member configured to be caused to swing by rotation of the rotary shaft member, a tool accessory driving mechanism configured to drive a tool accessory by swinging of the swinging member, a body housing the driving motor, the rotary shaft member, the swinging member and the tool accessory driving mechanism, and a vibration reducing mechanism configured to reduce vibration caused in the body. The vibration reducing mechanism includes a dynamic vibration reducer having an elastic member and a weight, and a connecting member connecting the weight and the swinging member. The vibration reducing mechanism is configured to reciprocate the weight via the connecting member by the swinging of the swinging member.

An electric power tool dust collection system includes: a hammer drill, to which a dust suction bit is mounted; a dust collection device mounted to the hammer drill and including a suction portion (introduction port), a dust collection motor, a dust collection fan rotated by drive of the dust collection motor to generate a sucking force in the introduction port, and a dust collection portion (dust box) that stores powder dust suctioned from the introduction port; and exhaust flow paths (exhaust flow path and tubular flow path) respectively formed in the hammer drill and the dust collection device to lead exhaust that has passed through the dust box to a high-temperature portion (output portion) of the hammer drill.

An objective is to provide a technique to securely protect the striking tool even when the striking tool inadvertently falls down. A striking tool including a rotating shaft relatively rotatably connect a main body with a handle, a first elastic member reducing transmitting of vibration from the main body to the handle in a case that the handle relatively rotates to the main body, wherein the handle includes a battery mounting portion to which battery to drive the motor is attachable and the handle is arranged to relatively move to the main body across the rotating shaft, and an adjuster such that the relative movement amount of the handle to the main body in a predetermined direction is adjusted to be larger than the relative movement amount in a direction other than the predetermined direction.

A method for detecting a transmission backlash in a hand-held power tool, the hand-held power tool comprising a drive motor that has a drive shaft, a tool spindle, and a transmission that, in respect of drive, connects the drive shaft to the tool spindle, includes actuating, in a first actuation, the drive motor at least until the value of a first variable, representing a drag torque, is at least approximately constant. The method includes, during the first actuation, determining a value of a second variable which is associated with the rotation of the drive shaft of the drive motor during the first actuation, and determining a value of a third variable, representing a transmission backlash, based upon a change in the second variable during the first actuation.

A percussion tool includes a housing having a top end, a bottom end, a front end, and a rear end. The housing defines a barrel portion, a handle portion opposite the barrel portion, and a motor housing portion between the barrel portion and the handle portion. The percussion tool also includes an electric motor positioned within the motor housing portion and a percussion mechanism driven by the motor and including a striker supported for reciprocation in the housing. The striker defines a striker axis in a reciprocating direction. The percussion tool further includes a battery receptacle supported by the housing and a battery pack removably coupled to the battery receptacle for providing power to the motor. The battery pack and the battery receptacle define a battery axis extending longitudinally through the battery pack and battery receptacle. The striker axis and the battery axis are parallel.

An electric tool is provided with a rotary striking mechanism unit converting the rotational force of a brushless motor to a striking force and applying the striking force to a tip tool. The required rated input of the motor is 1000-1300 W, the motor speed under fixed speed control is 1680010% (min.sup.1), and the variable Ku, which relates to the motor, is defined by the following expression Ku={(stator core outer diameter).sup.2(stator core lamination thickness)(total tooth width)(rotor outer diameter)}{(rated input)(motor speed under fixed speed control)}, wherein the stator core outer diameter, the stator core lamination thickness, the total tooth width and the rotor outer diameter are shown in mm, the rated input is shown in W, the motor speed is shown in min.sup.1, and the Ku value of the motor is set to 14.6<=Ku<=21.8.

The hand-held power tool has a tool holder (2) for holding a tool (4) along a working axis (12). A hammer mechanism (6) has a striker (15) that is moved periodically along the working axis at an impact rate. A drive control (18) of the hammer mechanism (6) sets the impact rate to a set point value. A vibration absorber (19) has an oscillator (21) that moves along the working axis (12) about a resting position and one or multiple springs (20) that drive the oscillator (21) back into the resting position. A calibration phase comprises the following steps: detection of an acceleration using the acceleration sensor (24); determination of a minimum of the acceleration by varying the impact rate in a range of between 90% and 110% of the set point value; and adjusting the set point to the impact rate associated with the ascertained minimum.

A handheld power tool has a tool socket (2) to hold a tool (4) along a working axis (11), a motor (5) and a slip clutch (21) having a number of blocking elements. A sensor (27) serves to record a measured signal (28) as the measure of vibrations inside the handheld power tool (1). A band-pass filter (29) has a pass range in which a frequency lies that is equal to the product of the rotational speed of the wheel (22) on the drive side and the number N of blocking elements (24). The measured signal (28) filtered by the band-pass filter (29) is fed to an evaluation unit (30). When the filtered measured signal (28) exceeds a limit value, the evaluation unit (30) reduces the rotational speed of the motor (5).