Abstract: A hand-held knockout driver includes a main housing having a handle portion, a motor positioned within the main housing, a pump assembly driven by the motor, and a secondary housing coupled to the main housing and defining a bore therein. The hand-held knockout driver also includes a working piston moveable within the bore from a rest position to an actuated position to define a piston throw distance therebetween. The hand-held knockout driver also includes a draw stud coupled to the working piston, a die coupled to the secondary housing, and a punch coupled to the draw stud opposite the working piston for movement therewith relative to the die. The die has a depth greater than the piston throw distance.

Abstract: A fluid pressure cylinder. A first stepped section having a greater diameter than a cylinder chamber is formed at one end of a cylinder tube constituting a fluid pressure cylinder. A disc-shaped head cover is inserted into the cylinder chamber. The one end is pressed and plastically deformed by a staking jig to form a deformed section, and the head cover is affixed within the first stepped section by the deformed section. As a result of this configuration, the head cover can be more firmly affixed while the sealing effect between the cylinder tube and the head cover is ensured. This eliminates need for a seal means and an engagement means which is used to affix the head cover, and consequently, the number of parts can be reduced.

Abstract: The invention relates to a hydraulic percussion device intended to be fitted on a base vehicle, the device comprising: a housing comprising a closing plate; a power cell mounted in the housing; and a damper connecting the power cell and the closing plate, the damper comprising a body rigidly connected to the power cell opposite the closing plate; a chamber provided inside the body; and a closing piston which is movable inside the chamber and capable of abutting against the closing plate in order to seal the chamber, the chamber being intended to contain a compressible fluid for damping the movements of the power cell in relation to the housing.

Abstract: A hand-held machine tool for a striking tool has a motor, an impact mechanism, a spool valve, and a pneumatic chamber. The impact mechanism has an exciter piston moved by the motor, and a hammer coupled to the exciter piston via a pneumatic chamber between the exciter piston and the hammer, and a striker in front of the hammer in the striking direction. In a working position counter to the striking direction, the striker bears on a stop, in a starting position the striker is offset in the striking direction relative to the working position, and in a rest position the striker is offset in the striking direction relative to the starting position. In the starting position, the hammer bearing on the striker closes the spool valve and, in the rest position, the hammer bearing on the striker opens the spool valve.

Abstract: Disclosed is an actuator for axial displacement of an object, including a cylinder volume having a first portion, and an actuator piston disc displaceable in the axial direction in the cylinder volume between inactive and active positions, an inlet channel between a pressure fluid inlet and the first portion of the cylinder volume, a first inlet valve body in the inlet channel, an outlet channel between the first portion of the cylinder volume and a pressure fluid outlet, and an outlet valve body in the outlet channel. The slave piston is displaceable in a bore, the slave piston displacing the first inlet valve body to an active position, and interacting with an opening connecting the bore and a control pressure channel, the opening having a first flow area with the slave piston in its inactive position and a larger second flow area with the slave piston in its active position.

Abstract: A setting device is provided, comprising a housing, a combustion chamber having an ignition apparatus, a storage container having a container wall for storing fuel, a dosing apparatus for adding a specified volume of fuel to the combustion chamber, an apparatus, such as a firing pin, for inserting a setting element into a setting object, wherein a setting force can be applied to the apparatus as a result of the pressure of combustion gas such that the apparatus is operable by combustion force, a control unit, and a temperature sensor for detecting the temperature of the fuel in the storage container. The setting device is designed such that, while the storage container is connected to the setting device, the temperature sensor mechanically contacts an outer surface of the container wall, for indirect detection of the temperature of the fuel.

Abstract: A bottom-hole feeding mechanism comprising: a cylinder (1), a screw spindle (2) engaging with the cylinder (1) by means of a non-stopping splined screw pair (3), a first piston (6) received within the cylinder (1) and coupled with the screw spindle (2) and a hollow rod (8), an axial spindle (4) arranged along the cylinder (1) axis and engaging the cylinder (1) by means of an axial splined pair (5), a second piston (7) rigidly coupled with the axial spindle (4) and engaging the inner surface of the cylinder (1) and the outer surface of the hollow rod (8), wherein the hollow rod (8), the first piston (6), the second piston (7) and the cylinder (1) form a closed chamber (9) comprising a throttle (10), hydraulic channels (11) on the body of a valve (21), and a float (12).

Abstract: The pneumatic hammer includes a hollow housing with handles for the user. A pneumatic driver is mounted inside the housing with an air tank for pressurized air. A reciprocating hammer assembly is slidably mounted inside the pneumatic driver and includes a hammer with a sharp hammer tip. The hammer is substantially hollow to efficiently capture released air from the air tank and drive the same. An alignment collar extends out of the housing and couples to the hammer assembly to set alignment of the hammer against an object to be impacted. The collar is normally locked in place. A control assembly is coupled to the housing, the pneumatic driver, and the collar to selectively release air driving the hammer out of the housing and unlock the collar for slidable movement into the housing.

Abstract: A hammer assembly including a hammer housing and a work tool movably supported in the hammer housing is provided. A gas chamber is defined in the hammer housing and contains a compressible gas. An accumulator assembly includes an interior space. A barrier divides the interior space into a first interior portion containing a compressible gas and a second interior portion configured to receive a pressurized fluid. The barrier is configured to be movable in response to changing the amount of pressurized fluid in the second interior portion and such that movement of the barrier varies the volume of the first interior portion. The first interior portion is in communication with the gas chamber. A control valve assembly is configured for selectively placing the second interior portion of the accumulator assembly in communication with a pressurized fluid source.

Abstract: A power wrench has a rotation motor, and a hydraulic pulse unit. The pulse unit includes an inertia drive unit connected to the motor. The inertia drive unit includes an oil chamber with an impulse generating mechanism, and an output spindle extending into the oil chamber to receive torque impulses. The inertia drive unit has a cylindrical member defining the oil chamber, a rear end wall, and an air separator element co-rotating with the wall and having a substantially axially facing surface which together with a congruent surface on the rear end wall forms oil passages in the form of a clearance gap through which oil mixed with air is circulated between one or more oil inlet openings, past one or more air outlet openings, to one or more oil outlet openings. Air is extracted from the oil and is gathered in a centrally located air collecting chamber.

Abstract: The present invention relates to a hydraulic percussive arrangement comprising a displaceable arrangement (1) in a casing (11), in which casing (11) the following are arranged at the displaceable arrangement (1): a first chamber (5) connected to a return line (7) for hydraulic oil, a bushing (6) on a first side of the first chamber (5) and separated from the first chamber (5) by a first gap (12) along the displaceable arrangement (1), and a second chamber (2) with a higher pressure of hydraulic oil than that of the first chamber (5) and arranged on a second side of the first chamber (5), separated from the first chamber (5) by a second gap (4) along the displaceable arrangement (1). According to the invention, a third chamber (8) is fixed arranged between the second gap (4) and the first chamber (5) and the third chamber (8) is connected to the first chamber (5) not only by a first passage (14) but also by a third gap (9) along the displaceable arrangement (1).

Abstract: The machine tool according to the with a pneumatic hammer mechanism comprises a motorized exciter, a guiding tube, and a piston-shaped beater. The piston-shaped beater is guided by an interior surface of the guiding tube along an operating axis and with the exciter encloses an air spring in a guiding tube. The beater shows a cup-shaped basic body with an open hollow space facing the exciter and an inset filling the hollow space. The basic body is made from a first material with a first density and the insert is made from a material with a second density, which is lower than the first density.

Abstract: A pneumatic actuator for use in pneumatic impact tools of the type used to engrave jewelry, and an impact tool adapted for the pneumatic actuator. The actuator includes a cylinder body with a pneumatic chamber housing a piston assembly reciprocating in response to pulses of pressurized air. The piston assembly includes a piston base and a striker pin in the pneumatic chamber, an outer end of the striker pin extending through and residing outside a forward end of the chamber. The outer end of the striker pin has an enlarged striker head of greater mass than the striker pin and/or the piston base in the chamber. A pneumatic impact tool is also disclosed, and includes a forward stylus section having a guide bore for the striker head and holding a graver assembly in spaced relationship to the striker head.

Abstract: The machine tool according to the with a pneumatic hammer mechanism comprises a motorized exciter, a guiding tube, and a piston-shaped beater. The piston-shaped beater is guided by an interior surface of the guiding tube along an operating axis and with the exciter encloses an air spring in a guiding tube. The beater shows a cup-shaped basic body with an open hollow space facing the exciter and an inset filling the hollow space. The basic body is made from a first material with a first density and the insert is made from a material with a second density, which is lower than the first density.

Abstract: There is provided a hammer raising device. The hammer raising device is configured to increase striking intensity by eliminating fluid resistance when a piston raised upward moves downward. To achieve this, the hammer raising device includes a hydraulic control valve that controls a supply of a fluid, a sub cylinder to which the fluid is supplied by an operation of the hydraulic control valve, a sub piston that is partially accommodated within the sub cylinder, and is raised or lowered by the fluid, a main piston that comes in close contact with a longitudinal end of the sub piston to be raised by the raising of the sub piston, and is lowered when the closely contacted longitudinal end of the sub piston is separated, and a main cylinder that accommodates the main piston.

Abstract: An exemplary embodiment of the jet hammer includes an outer sleeve, impact assembly, and a valve assembly. The impact assembly is positioned in sliding relation to the outer sleeve to provide the impact of the jet hammer. The valve assembly generally comprises a cap screw, adjustment sleeve, valve port, inner compression spring, outer compression spring, and lock nut. The inner compression spring is relatively less compressible than the outer compression spring. In operation, fluid enters the valve assembly and acts on the compression springs forming an operational seal between the valve assembly and the impact assembly thereby slidingly displacing the outer sleeve from the impact assembly. Once the pressure acting on the valve assembly is released, the main compression spring decompresses forcefully causing an impact which is translated onto the obstruction or item to be struck.

Abstract: A hammer drill includes, in a cylinder accommodated in a housing, a piston configured to advance and retract and an impact element to operate together with the piston with an air chamber interposed therebetween, and a bit mounted in a front part of a tool main body so that an impact operation can be transmitted to the bit by advancing and retracting movement of the impact element. Vent holes are provided in the cylinder, and configured to discharge air in the air chamber to outside of the cylinder, and to introduce the air outside the cylinder into the air chamber by the movement of the piston. One of the vent holes is located at a center of an upper half of a periphery of the cylinder and the other vent hole is located in a lower half of the periphery of the cylinder.

Abstract: A hydraulic pulse tool includes a power supply unit, a drive unit electrically connected to the power supply unit, a hydraulic pulse torque generating unit coupled to the drive unit and rotatable by the drive unit to produce impacts for causing the drive to produce an electric current change, and a control unit for judging the electric current change and controlling the operation of the drive unit subject to the judgment result. Subject to the above-stated technical characteristics, the hydraulic pulse tool, in addition to the shutoff function, can reduce errors in judgment and achieve multi-stage torque output control.

Abstract: A pressure protection valve is provided which provides a fluid short circuit between a fluid pressure inlet of a hydraulic tool such as a hydraulic hammer and a low pressure region when the pressure at the fluid pressure inlet exceeds a first trigger pressure equal to a predetermined permissible pressure. This prevents damage to the hydraulic tool which can arise through operation at excessive fluid flow or pressure from hydraulic fluid supplied by a carrier vehicle. The pressure protection valve may maintain fluid communication between the fluid pressure inlet and the low pressure region until the pressure at the fluid pressure inlet reduces to a pressure below a predetermined second trigger pressure which is less than the first trigger pressure, to prevent further operation of the tool until the flow of fluid to the fluid pressure inlet has been stopped by an operator.

Abstract: An oil pulse tool includes a motor, an oil pulse unit, an output shaft on which a front end tool is attached, a torque detecting sensor for detecting generation of an impact torque, and an operating portion configured to detect a time period between a first impact torque detected by the torque detecting sensor and a second impact torque detected by the torque detecting sensor. The second impact torque is smaller than the first impact torque. The operating portion carries out a notification when the time period between the first impact torque and the second impact torque is less than a predetermined evaluation value for the time period between the first impact torque and the second impact torque.

Abstract: An impact torque adjusting device of a hydraulic torque wrench enhances the precision of the magnitude of the impact torque generated, shortens the generation period of impact torques, and enhances the durability when rotating in either of two directions, that is, in normal rotation (when tightening) and in reverse rotation (when loosening). A working fluid path 11b communicates with the inside of a liner 7 serving as a high-pressure chamber H and a low-pressure chamber L when an impact torque is formed. A valve body 11d biased in a direction of releasing the working fluid path 11b is disposed in the working fluid chamber 11b. At the rear back side of the valve body 11d, an oil chamber 15e is formed to communicate with a blade insertion part 8a of a main shaft 8 by way of fluid paths 7c, 7d formed in liner lids 7a, 7b.

Abstract: The invention relates to a tool for a breaking hammer, a breaking hammer, and the use of a breaking hammer. The breaking hammer includes a percussion device, the percussion piston of which providing impacts to the tool for breaking rock. An impact surface of the tool has a curved form surface that has a radius of curvature and a center axis on the longitudinal axis of the tool. The direction of the centre axis is transverse to the plane through the longitudinal axis of the boom of a work machine.

Abstract: Disclosed herein is a hydraulic hand tool. The tool includes a frame, a hydraulic drive, a drive shaft, and a seal assembly. The hydraulic drive is connected to the frame and includes a housing. The drive shaft extends from the hydraulic drive. The seal assembly is located between the drive shaft and the housing. The seal assembly includes a first seal member, a second seal member, and a carrier ring. The first seal member is in contact with the housing. The second seal member is in contact with the drive shaft. The carrier ring has an outer annular groove and an inner annular groove. The first seal member is located within the outer annular groove. The second seal member is located within the inner annular groove. The carrier ring includes a polymer material configured to elastically deform in response to a hydraulic load from hydraulic fluid at the hydraulic drive.

Abstract: Various embodiments herein provide a remotely adjustable feed system for remotely controlling the movement of a tool head on a machining tool along an axis of motion by means of converting reciprocal linear motion, i.e., back and forth linear motion, into rotary motion. The rate of movement of the tool head along the axis of motion may be controlled by varying the distance of linear motion in each cycle of linear reciprocal motion and/or by varying the rate of linear reciprocal motion cycles per unit time. Alternatively, or in addition, the rate of movement of the tool head along the axis of motion may be controlled by varying the amount of rotary motion that results from a given amount of reciprocal linear motion. Additionally, in some embodiments, the movement of the tool head may be controlled by directly controlling the rotary motion that drives the tool head along the axis of motion.

Abstract: A sleeve body with bearings interposed between the sleeve body and a center shaft portion is integrally coupled to an oil pulse generator. A coupling body is rotatable together with the output portion. Balls are fitted between an outer surface of the sleeve body and an inner surface of the coupling body. Cam grooves are L-shaped in plan view, and formed in a portion of the outer surface of the sleeve body at which the balls are fitted. Rotation of the output portion is transmitted from the coupling body to the sleeve body and the oil pulse generator via the balls. When rotational speed between the sleeve body and the coupling body is different, the balls relatively turn in the cam grooves to move the coupling body forward against an urging force of the coil spring so as to relieve an impact.

Abstract: Disclosed is a hydraulic breaker.

Abstract: A pile driving system for driving a pile. The pile driving system comprises a housing assembly, a hammer, a helmet member, and a lifting system. The housing assembly defines at least one vent opening is arranged at a first vent location along the drive axis, and at least one vent opening is arranged at a second vent location along the drive axis. When the hammer drops and is above the first vent location, ambient air flows from the main chamber through the vent openings formed at the first and second vent locations. When the hammer is below the first vent location and above the second vent location, ambient air flows from the main chamber through the vent openings formed at the second vent location. When the hammer is below the second vent location, air within the main chamber is compressed to preload the helmet member.

Abstract: A fluid pressure driven, high frequency percussion hammer for drilling in hard formations is presented. The hammer piston (20) of the percussion hammer has a relatively large and longitudinally extending bore (41) that provides minimal flow resistance for a drilling fluid flowing through the bore (41) during the return stroke of the hammer piston (20). The bore (41) is closeable in the upstream direction by a valve plug (23) that follows the hammer piston (20) during the stroke. The valve plug (23) is controlled by a relatively long and slender valve stem (49) that is mechanically able to stop the valve plug (23) by approximately 75% of the full stroke length of the hammer piston (20) and separates the plug (23) from a seat ring (40). Thus the bore (41) opens up such that the bore fluid can flow there trough, and the inherent tension spring properties of the valve stem (49) returns the valve plug (23) so rapid that it will be good through flow during return of the hammer piston (20).

Abstract: Pressurized air pick device with variable control that comprises a cylinder and piston assembly for actuating a picking member, and a distribution portion with variable control of the pressurized air to said cylinder and piston assembly, the distribution portion including an upper body, a lower ring and a movable fluid-distribution slider capable of sliding between the body and the ring, characterized in that the distribution portion is housed in the cylinder of the cylinder and piston assembly at the upper portion thereof and coaxially therewith, the variable control for the fluid is housed in the head of the cylinder closing the upper portion of the cylinder connected to a fluid-supply section, and said upper portion of the cylinder includes two channels for conveying pressurized air in tight communication with the distribution portion through the radial channels thereof.

Abstract: In an electric hammer, ridges are provided in an outer surface of a barrel, grooves are provided in an inner surface of a front cover, and rotation of the front cover with respect to the barrel is prevented by fitting the ridges in the grooves. A flange, which is latched on a stepped portion provided in front of the ridges and the grooves in the inner surface of the front cover, is provided in a peripheral edge of a lock ring, and forward movement of the front cover is restricted by latching the flange on the stepped portion.

Abstract: A fluid powered percussion tool 1 has a housing 2 with a supply channel for pressurized fluid 3, a percussion mechanism 4, a swing joint 5 arranged to carry the percussion mechanism 4 relative to the housing 2 at a point situated between the forward end A and the rear end B of the percussion mechanism 4, at least one elastically resilient element 6 arranged between the housing 2 and the percussion mechanism 4 at a distance from the swinging joint 5 and arranged to load the percussion mechanism 4 against a neutral position in the housing 2 and to absorb the vibrational movements of the percussion mechanism 4, and a flexible connection for pressurized fluid 7 for distribution of pressurized fluid from the supply channel for pressurized fluid 3 to the percussion mechanism 4. The elastically resilient element 6 includes a conical spring 8. The flexible connection for pressurized fluid 7 includes a hose 11.

Abstract: According to an aspect of the present invention, there is provided a rotary striking tool includes: a motor; an oil pulse unit that is driven by the motor; an output shaft that is coupled to the oil pulse unit so that a tip tool can be attached to the output shaft; a first detection unit that detects a rotation angle of the motor and outputs a first output signal; a second detection unit that detects an impact generated at the oil pulse unit and outputs a second output signal; and a control unit that controls a rotation of the motor, wherein the control unit uses a portion of the second output signal based on the first output signal for control of the rotation of the motor.

Abstract: The invention concerns a hydraulic, valveless impact mechanism for use in equipment for the machining of at least one of rock and concrete comprising a machine housing (105; 205) with a cylinder bore, a piston (110; 210) mounted such that it moves within this bore arranged to carry out when in operation repetitive reciprocating motion relative to the machine housing and in this way to deliver impact directly or indirectly on a tool connectable to the equipment for machining at least one of rock and concrete, and where the piston includes a driving part (140; 240) that separates a first drive chamber (160; 260) and a second drive chamber (125; 225), with an effective volume that is greater than that of the first drive chamber.

Abstract: The invention concerns a hydraulic striking tool for application in rock and/or concrete cutting equipment containing a machine housing (100;200) with a cylinder (115;215) with a moveably mounted piston (145;245) which during operation performs a repetitive forward and backward movement relative to the machine housing (100;200) and directly or indirectly strike a rock and/or concrete cutting tool (155;255), and where the piston (145;245) includes a driving part (165;265) which separates a first (120;220) and a second (105;221) driving chamber formed between the piston (145;245) and the machine housing (100;200) and where these driving chambers are arranged to include a pressurised working fluid during operation. The total volume V of the first and second driving chambers is inversely proportional dimensioned to the square of a for the striking tool recommended maximal pressure p, as well as proportional, by a proportionality constant k within the interval 5.3-21.

Abstract: A control system for use in conjunction with a primary power system and operable to control a pneumatically powered hand-held tool broadly comprises an air delivery assembly operable to communicate with a pressurized air source; a control assembly including an exhaust line from the primary power system and to the control assembly, a spool valve in fluid communication with the supply line and the exhaust line, and a control line in fluid communication with the spool valve and the hand-held tool; a tool assembly comprising the hand-held tool for performing delicate hand working operations; and a housing for at least partial storage of the air delivery assembly and the control assembly. The primary power system and the control system operate in conjunction with each other to both power and precisely control a pneumatically powered hand-held tool.

Abstract: A piston cylinder is formed inside a ram and is fitted with a piston attached to a stationary hollow piston rod, creating a upper piston chamber for receiving pressurized hydraulic fluid, which causes the ram to rise as the volume of the upper piston chamber is expanded due to the hydraulic pressure and increasing volume of hydraulic fluid. When the ram reaches predetermined desired height, hydraulic pressure is released by opening a directional valve, allowing the ram to drop. A lower piston chamber is sealed and filled with gas. A moveable shuttle member that reciprocates up and down inside a hollow piston rod in response to the changing volume of the lower piston cylinder, facilitating the evacuation of hydraulic fluid from the upper piston chamber. An alternative embodiment uses a single fluid and has no shuttle member.

Abstract: A pneumatic impact device and method provide a high powered striking force against a target object. The device includes a core shell that houses a piston sub-assembly and a sear arm sub-assembly, and that further defines a forward gas chamber and a rearward gas chamber. The rearward gas chamber is loaded with compressed fluid via a handle actuator. A mostly external sear trigger assembly responds to the impact of a striker plate against the target object, thereby releasing a sear arm that then releases a piston, which is then accelerated forward by the compressed fluid charge. The device can be re-set manually via compressed fluid (e.g., air) in one embodiment, or automatically via a spring mechanism in another embodiment.

Abstract: A power tool having a housing divided into two parts which are interconnected by a thread joint. Internal threads are provided on the housing parts. A tubular connection element has two external axially spaced thread sections which are provided for engagement with the internal threads on the housing parts. The tubular connection element has a thin walled waist section located between the external thread sections to provide a certain elastic deformation as a tightening torque is applied on the thread joint to thereby increase the clamping length of the thread joint. A resilient ring is carried on the waist section and is arranged to be elastically deformed by squeezing between the housing parts and the connection element at tightening of the thread joint, thereby providing a rotation locking friction force on the thread joint.

Abstract: The present invention relates to a hydraulic percussive arrangement comprising a displaceable arrangement (1) in a casing (11), in which casing (11) the following are arranged at the displaceable arrangement (1): a first chamber (5) connected to a return line (7) for hydraulic oil, a bushing (6) on a first side of the first chamber (5) and separated from the first chamber (5) by a first gap (12) along the displaceable arrangement (1), and a second chamber (2) with a higher pressure of hydraulic oil than that of the first chamber (5) and arranged on a second side of the first chamber (5), separated from the first chamber (5) by a second gap (4) along the displaceable arrangement (1). According to the invention, a third chamber (8) is fixed arranged between the second gap (4) and the first chamber (5) and the third chamber (8) is connected to the first chamber (5) not only by a first passage (14) but also by a third gap (9) along the displaceable arrangement (1).

Abstract: Rock drilling machine (10) comprising a piston that is arranged to move back and forth in a chamber (12a, 12b) when the rock drilling machine (10) is in use, a cavitation-sensitive component (14), and an oil channel that is arranged to extend between the chamber (12a, 12b) and said cavitation-sensitive component (14). The oil channel comprises a series of restrictions (18) and oil volumes (20) to hinder the movement of cavitation bubbles through said oil channel.

Abstract: The machine tool according to the with a pneumatic hammer mechanism comprises a motorized exciter, a guiding tube, and a piston-shaped beater. The piston-shaped beater is guided by an interior surface of the guiding tube along an operating axis and with the exciter encloses an air spring in a guiding tube. The beater shows a cup-shaped basic body with an open hollow space facing the exciter and an inset filling the hollow space. The basic body is made from a first material with a first density and the insert is made from a material with a second density, which is lower than the first density.

Abstract: A production method provides for punching holes in a metal strip, cold-forming the metal strip to form a guide tube, and joining the lengthwise edges of the metal strip to each other by a seam or teeth so as to create a uniform material. Subsequently, a piston-like striker is inserted into the guide tube.

Abstract: A motor controller comprises a processor selectively outputting an on-signal to either one of an upper arm switching element and a lower arm switching element based upon a detected position by the position sensor, gate drivers inputting a driving voltage to the gates of the switching elements by shifting a level of the on-signal from the processor to the upper arm switching element and a bootstrap capacitor configured to be charged while the upper arm switching element is turned off and to behave as a voltage supply for the gate driver while the upper arm switching element is turned on. The processor is configured to reduce a set duty ratio when the set duty ratio is equal to or larger than a predetermined value (e.g. 80 percents) and a rotational position of the motor does not change for a first predetermined time. This motor controller can prevent the switching element from a burnout even if the motor is locked.

Abstract: A hand-held knockout driver for use with a punch and die. The hand-held knockout driver including a housing having a handle portion, a motor positioned within the housing, the motor having a drive shaft defining a first axis, a pump assembly positioned within the housing, the pump assembly having a piston moving along a second axis, a dump valve positioned within the housing, the dump valve defining a third axis, and a working piston moveable with respect to the housing along a fourth axis.

Abstract: A drill hammer for the three operation modes of drilling, chiseling, and hammer-drilling has a motor with a motor shaft; a gear with an intermediate shaft, a driving gear wheel, a toothed slaving shaft , a shifting hub, and a driven gear wheel; a percussion mechanism with a wobble disk and a wobble gear wheel; and a driven shaft with a driving gear wheel and a drill chuck. The gear is configured to be changed over easily without axial displacement of running gears that mesh with one another so that the drill hammer is more robust, shorter or more compact, and lighter in weight. The drill hammer is thus simply and economically constructed and whose efficiency is not impaired by the gear shifting mechanism.

Abstract: A hammer drill includes, in a cylinder accommodated in a housing, a piston configured to advance and retract and an impact element to operate together with the piston with an air chamber interposed therebetween, and a bit mounted in a front part of a tool main body so that an impact operation can be transmitted to the bit by advancing and retracting movement of the impact element. Vent holes are provided in the cylinder, and configured to discharge air in the air chamber to outside of the cylinder, and to introduce the air outside the cylinder into the air chamber by the movement of the piston. One of the vent holes is located at a center of an upper half of a periphery of the cylinder and the other vent hole is located in a lower half of the periphery of the cylinder.

Abstract: A hand-held power tool includes a motor-driven percussion mechanism. The percussion mechanism includes a guide tube (21) and a reciprocating driving member (22) displaceable in the guide tube (21) for driving, via a gas spring, an impact member (23) likewise displaceable in the guide tube (21). The percussion mechanism further includes a motor-driven eccentric wheel (17) rotatable about an axis (D) which is spaced from the percussion mechanism axis (S) in a direction perpendicular to the percussion mechanism axis (S) by a distance (X). A connection rod (29) is eccentrically supported on the eccentric wheel (17) and connected to the driving member (22) for converting a rotational movement of the eccentric wheel (17) into a reciprocating movement of the driving member (22).

Abstract: A downhole tool comprises a pulse generator that can generate longitudinal pulses in a drill string. A poppet is longitudinally moved in and out of an orifice in the pulse generator reducing the flow of drilling mud temporarily, generating a longitudinal pulse. The longitudinal pulse generator may be combined with a conventional transverse pulse generator to create a pulse generator capable of generating pulses in both transverse and longitudinal directions.

Abstract: The invention relates to a tool that includes a tool holder, which has on its first end a tool holder recess that is adapted to the contours of a rotating spindle driver and a tool recess on a second end that lies opposite the first end. The tool holder also includes a tool head that can be inserted into the tool recess. For the optimal machining of a workpiece, attempts were previously made to provide an oscillating unit in the spindle of the machine, to initiate oscillations in the tool head. The disadvantage of said known constructions is that all available tools have to be synchronized with the oscillation unit. The invention overcomes said disadvantage by equipping the tool holder with an oscillating motor.

Abstract: A pulse drilling machine (1;1?) for the generating of shock wave pulses in a tool direction (R) has an impulse piston (4;4?) with a housing (2), and a device (8) for abruptly changing fluid pressure influencing the impulse piston to achieve a force resultant on the impulse piston in the tool direction to generate a shock wave pulse in a drill string (13; 13?) which is connected to the machine, a first fluid chamber (14;3?) inside the housing which in operation is arranged to exert a pressure in the tool direction on the impulse piston. The machine has a fluid flow channel (11; 18; 19), which includes a device for damping fluid flow flowing from the first fluid chamber through the fluid flow channel obtained when influencing the impulse piston (4; 4?) in a direction opposite to the tool direction (R) by rock reflexes in the drill string during drilling.