A dust collection box for a dust extractor includes first and second air inlet chambers, an air inlet aperture through which air is drawn into the first air inlet chamber, an air outlet aperture through which air is dawn out of the second air outlet chamber, an air intermediate chamber formed in the housing, and a filter mounted within the housing. The filter includes a first part through which air passes from the air inlet chamber to the air outlet chamber, and a second part through which air passes from the air inlet chamber to the air intermediate chamber. An ambient air aperture is formed in the wall of the housing. A valve disposed proximate the ambient air aperture is switchable to connect the air intermediate chamber to only one of the air outlet chamber or the ambient air aperture.

A vibration reducing structure of pneumatic hammer includes a handle having a concave room with a bottom wall and an air inlet channel communicating with the concave room. A control valve is disposed in the air inlet channel. A movable inner tube shell is accommodated in an outer tube shell coupled with the concave room and extends a rear bucket portion into the concave room. A movable hammer member, an air inlet valve for activating the hammer member and a hole communicating the air inlet channel to the air inlet valve are disposed in the inner tube shell. An air room is formed between the bottom wall and an end wall of the inner tube shell. A communicating channel communicates the air inlet channel to the air room for air with high pressure entering the air room.

A vibration reducing structure of pneumatic hammer includes a handle having a concave room with a bottom wall and an air inlet channel communicating with the concave room. A control valve is disposed in the air inlet channel. A movable inner tube shell is accommodated in an outer tube shell coupled with the concave room and extends a rear bucket portion into the concave room. A movable hammer member, an air inlet valve for activating the hammer member and a hole communicating the air inlet channel to the air inlet valve are disposed in the inner tube shell. An air room is formed between the bottom wall and an end wall of the inner tube shell. A communicating channel communicates the air inlet channel to the air room for air with high pressure entering the air room.

An air impact tool includes an inner tubular member that is connected to the barrel. The inner tubular member has an annular wall and a cavity. The annular wall has exhaust hole. An air flow channel communicating with the air flow control valve and the cavity is defined inside the annular wall. The air flow channel is formed with a first air inlet. A hammer is in the cavity. The hammer is in close contact with the annular wall. A cylindrical gap is defined between a middle section of the hammer and the annular wall. The hammer has an exhaust passageway communicating with the cavity and the cylindrical gap. When the compressed air is injected into the cavity from the first air inlet, the hammer is pushed back, and the compressed air is exhausted via the exhaust passageway, the cylindrical gap and the exhaust hole in sequence.

An air impact tool includes an inner tubular member that is connected to the barrel. The inner tubular member has an annular wall and a cavity. The annular wall has exhaust hole. An air flow channel communicating with the air flow control valve and the cavity is defined inside the annular wall. The air flow channel is formed with a first air inlet. A hammer is in the cavity. The hammer is in close contact with the annular wall. A cylindrical gap is defined between a middle section of the hammer and the annular wall. The hammer has an exhaust passageway communicating with the cavity and the cylindrical gap. When the compressed air is injected into the cavity from the first air inlet, the hammer is pushed back, and the compressed air is exhausted via the exhaust passageway, the cylindrical gap and the exhaust hole in sequence.

A power tool, such as a rotary hammer, includes a housing, an output shaft for mounting a tool accessary and a motor having a motor shaft that generates a rotational output for rotating and linearly hammering the output shaft. The rotational output of the motor shaft is coupled to the output shaft via a driving mechanism that includes a hammer mechanism. An intervening member is axially movable relative to the motor shaft and is operably coupled between the motor shaft and the hammer mechanism. The hammer mechanism and the output shaft are supported by a movable support that is axially movable relative to the housing. Because the output shaft and the driving mechanism are movable relative to the motor and the housing, which preferably includes handle, via the intervening member and the movable support during hammering operations, vibration generated during hammering operations can be dampened before reaching the housing.

A power tool, such as a rotary hammer, includes a housing, an output shaft for mounting a tool accessary and a motor having a motor shaft that generates a rotational output for rotating and linearly hammering the output shaft. The rotational output of the motor shaft is coupled to the output shaft via a driving mechanism that includes a hammer mechanism. An intervening member is axially movable relative to the motor shaft and is operably coupled between the motor shaft and the hammer mechanism. The hammer mechanism and the output shaft are supported by a movable support that is axially movable relative to the housing. Because the output shaft and the driving mechanism are movable relative to the motor and the housing, which preferably includes handle, via the intervening member and the movable support during hammering operations, vibration generated during hammering operations can be dampened before reaching the housing.

An apparatus for injecting impedance into a high voltage (HV) transmission line is disclosed. The apparatus comprises a plurality of modular flexible alternating current transmission systems (FACTS) based impedance injection units (IIUs), each modular FACTS based IIU without fault current protection. The apparatus further comprises a fault current protection module external to the modular FACTS based IIUs. The fault current protection module is coupled to the modular FACTS based IIUs to provide fault current protection to the modular FACTS based IIUs.

A movable support at least partially supports a final output shaft and a driving mechanism, and is integrally movable relative to a housing in an axial direction of a driving axis. A biasing member biases the movable support toward a front side in the axial direction. A first guide shaft extends in the axial direction and slidably guides the movement of the movable support in the axial direction. At least one intermediate shaft rotates in response to rotation of a motor shaft and transmit power of the motor to the driving mechanism. At least one bearing supports an end portion of the at least one intermediate shaft is located in the front side in the axial direction. A single metal support is immovable relative to the housing and supports the at least one bearing. The single metal support has a first hole for partially receiving the first guide shaft.

A movable support at least partially supports a final output shaft and a driving mechanism, and is integrally movable relative to a housing in an axial direction of a driving axis. A biasing member biases the movable support toward a front side in the axial direction. A first guide shaft extends in the axial direction and slidably guides the movement of the movable support in the axial direction. At least one intermediate shaft rotates in response to rotation of a motor shaft and transmit power of the motor to the driving mechanism. At least one bearing supports an end portion of the at least one intermediate shaft is located in the front side in the axial direction. A single metal support is immovable relative to the housing and supports the at least one bearing. The single metal support has a first hole for partially receiving the first guide shaft.