Abstract: Provided is a nut and a bolt tightening method for fastening an object, wherein a tightening force is applied on the object by rotating a nut or a bolt in a state in which a predetermined tension force is applied on the bolt in the axial direction of the bolt. When the tensile force exerted on the bolt decreases as the tightening force increases and after a timing when an inflection point occurs in a time course change in a ratio of an amount of change in the tensile force exerted on the bolt to an amount of change in an angle of rotation of the nut or the bolt, the tightening resulting from the rotation of the nut or bolt is terminated and the tensile force applied on the bolt is removed.

Abstract: Computer architectures and associated methods for real-time data processing are disclosed. In some embodiments, a trial adjudication request for a cost determination can be received by a first server and verified using a security protocol, wherein a password token of the trial adjudication request can be matched to a stored password token. The first server can transmit an adjudication command packet to a second server that includes at least one data set of a plurality of data sets and a command for a claim determination, and can receive a response packet from the second server. The first server can determine that a successful claim determination was performed by the second server from the response packet, and can transmit a reversal request packet to the second server which can cancel the successful claim determination. The first server can perform the electronic calculation using the claim data.

Abstract: An impact tool is provided which includes a drive source configured to rotate an output drive. A hammer is movable in a first direction to apply a rotational impact force on an anvil which rotates the output drive. A first hammer angle sensor set to a first signal channel and located proximate to a surface of the hammer. A plurality of regularly spaced targets are located on the surface of the hammer. Each of the plurality of regularly spaced targets are detectable by the first hammer sensor. And detection of one or more of the plurality of regularly spaced targets by the first hammer sensor indicates movement of the hammer.

Abstract: A method for controlling a level of screwing quality of a screwdriver relative to a predetermined screwing objective. The method includes: obtaining, at a predetermined angular frequency, a series of doublets representative of a rise in screwing torque for at least one screw, constituting a first table of values, each doublet including an angle value and a torque value; determining, from the first table, a second table of values presenting the torque as a function of the angle and being representative of the true characteristic of the at least one screw; determining a third table of values, presenting the torque as a function of the angle and being representative of disturbances induced by the screwdriver during the rise in torque, from the first and second tables; analysis of the third table, delivering information representative of a dispersion and/or a deviation relative to the screwing objective, resulting from the screwdriver-induced disturbances.

Abstract: An impact tool is provided which includes a drive source configured to rotate an output drive. A hammer is movable in a first direction to apply a rotational impact force on an anvil which rotates the output drive. A first hammer angle sensor set to a first signal channel and located proximate to a surface of the hammer. A plurality of regularly spaced targets are located on the surface of the hammer. Each of the plurality of regularly spaced targets are detectable by the first hammer sensor. And detection of one or more of the plurality of regularly spaced targets by the first hammer sensor indicates movement of the hammer.

Abstract: The present invention discloses a speed changing tool, comprising: a housing; a motor, disposed in the housing and outputting rotary power; a trigger switch, used for starting and stopping the motor; an output shaft; a gear transmission, which is disposed between the motor and the output shaft to transmit rotation of the motor to the output shaft, and comprises at least one group of gear system, a gear ring meshed with the gear system and a moving member, wherein the moving member can be moved between a first position and a second position and when in the first position and the second position, the moving member has different states relative to the housing, such that the gear transmission outputs a rotary speed of the motor with different speed reduction ratios; the variable speed tool further comprises a drive mechanism for driving the moving member to move between two positions, when a load of the output shaft reaches or exceeds a preset value, the drive mechanism can drive the moving member to move to the

Abstract: An electric working machine according to one aspect of the present disclosure includes an output shaft, a motor, a transmitting device, a drive device, a controller, and a current path. The transmitting device has transmittable allowable torque and transmits rotation of the motor to the output shaft. The drive device energizes the motor with electric supply from a battery in accordance with a command from outside the electric working machine. The current path is configured to be able to energize the motor with a current value larger than an allowable current value required to limit torque generated in the transmitting device due to rotation of the motor to the allowable torque or smaller.

Abstract: A calibration system includes a housing, a drive shaft within the housing, a load application apparatus operatively connected to the drive shaft to apply a force to the drive shaft, and a plurality of housing transducers operatively connected to the drive shaft to measure at least one of an in-line torque or a prevailing torque of the drive shaft. A method for calibrating a tool includes generating at least one of a pass or fail output from a processing unit based on whether a variance between a prevailing torque from a tool transducer and a prevailing torque from an external tool is within a predetermined variance threshold. A method for measuring prevailing torque in a tool includes determining whether a prevailing torque value is within a predetermined prevailing torque range and adjusting a shut-off threshold torque based on the prevailing torque.

Abstract: A screw fastening method includes reversely rotating a shaft part of a fastening tool in a direction of loosening one of an external thread and an internal thread, which is engaged with the shaft part, while one of the external thread in a non-screwed state and the internal thread in a non-screwed state, which is engaged with the shaft part, is pressed against the other thread, detecting collisions between thread ridges of the external thread and the internal thread using a sensor while the shaft part remains rotated reversely, determining whether or not a time interval between collisions detected by the sensor matches a theoretical cycle of collisions calculated from rotation speed of the shaft part, and fastening the external thread and the internal thread to each other by normally rotating the shaft part when it is determined that the time interval matches the theoretical cycle.

Abstract: The present disclosure provides a surgical instrument including an end effector, a drive member movable to effectuate a motion in said end effector, a motor operable to move the drive member to effectuate the motion in the end effector and a bailout assembly operable to perform a mechanical bailout of the surgical instrument in response to a bailout error. The bailout assembly includes a bailout door, a bailout handle accessible through the bailout door. The bailout handle is operable to move the drive member to effectuate a bailout motion in the end effector. A controller includes a memory and a processor coupled to the memory. The processor is configured to detect the bailout error. The processor is programmed to stop the motor in response to the detection of the bailout error.

Abstract: Embodiments of the present disclosure provide a control system including: a power wrench; and a controller operatively connected to the power wrench, wherein the controller is configured to perform actions including: directing an operative head of the power wrench to turn in response to a pressure-angle derivative of the operative head being below a predetermined threshold, defining an origin at an angular position of the operative head where the pressure-angle derivative of the operative head exceeds the predetermined threshold, directing the operative head to turn by an angular step in response to: the pressure-angle derivative of the operative head exceeding the predetermined threshold, and an angular differential of the operative head being less than a target value; and directing the operative head to cease turning in response to the angular differential of the operative head being approximately equal to or greater than the target value.

Abstract: A torsion-detecting pneumatic impact tool is provided. A hammering set having at least one hammering block and a rotating portion which is connected with each hammering block. A transmission shaft penetrates through each the hammering block. A torsion detecting unit includes a marking piece which has a plurality of blocks, at least two sensors which detect the marking piece and an processing unit which is electrically connected with each the sensor. The hammering set, the marking piece, and the rotating assembly rotating synchronously. When each the hammering block swing strikes the transmission shaft in a direction, the hammering set and the marking piece rotate reversely slightly because of the counterforce of swing strike. When the marking piece rotates reversely, the processing unit receives a signal of a degree of rotation of the blocks detected by the at least two sensors and computes a torsion value.

Abstract: A tightening device and a tightening method are able to check that a fastening member has been fastened to a desired set torque or greater after being tightened, without loosening the fastening member.

Abstract: An impact tool can be operated by generating an impact using an internal mechanism. The impact tool includes a control unit and sensors. The control unit controls the internal mechanism. The sensors output a signal for operating the internal mechanism or a signal for preparing the operation of the internal mechanism, to the control unit. Until a predetermined condition is established after the internal mechanism is operated, the control unit does not accept the input of the sensors.

Abstract: Illustrative embodiments of impact tools are disclosed. In at least one illustrative embodiment, an impact tool may comprise an impact mechanism including a hammer and an anvil. The hammer may be configured to rotate and to move between a disengaged position in which the hammer does not impact the anvil when rotating and an engaged position in which the hammer impacts the anvil when rotating, and the anvil may be configured to rotate when impacted by the hammer. The impact tool may further comprise an electronic controller configured to cause the hammer to (i) rotate in the disengaged position until reaching a threshold rotational speed and (ii) move from the disengaged position to the engaged position in response to the hammer achieving the threshold rotational speed.

Abstract: A rotary impact tool comprises: a motor that is a rotation driving source; an impact generation device for generating a pulse impact by rotation of the motor and applying a rotational torque to an output shaft by the impact; a torque sensor for measuring the torque applied to the output shaft; and a control means for halting the motor when the torque measured by the torque sensor has reached a target torque having been set. The control means is configured to change an increased torque value for one impact according to the target torque having been set.

Abstract: In a pneumatic impact wrench there is an output shaft that is connectable in a removable manner to a screw coupling member; a torque sensor, which is mounted on the shaft, sends signals to a control unit that calculates the energy transferred through the output shaft and controls the wrench on the basis of a comparison between the calculated energy and a predefined threshold value.

Abstract: In a clutch mechanism of a percussion driver drill, a plurality of engageable members held in a gear case is configured to be engageable with an end face of a final-stage internal gear, and a coil spring is configured to press the engageable members against the end face of the internal gear. The coil spring is disposed frontwardly of the engageable members between a switch member and an operating member of a vibration mechanism. A coupling member connected with the switch member and the operating member is disposed to pass through a gap between the plurality of engageable members and detour around a rear end of the coil spring.

Abstract: An impact rotation tool including a drive source, an impact force generation unit that generates an impact force for converting power from the drive source to pulsed torque, a shaft that transmits the pulsed torque to a bit used to perform a tightening task, a torque measurement unit that measures torque applied to the shaft as measured torque, a rotation angle measurement unit that measures a rotation angle of the shaft, a tightening torque calculation unit that calculates an angular acceleration from the rotation angle to calculate a tightening torque based on the angular acceleration and the measured torque, and a controller that controls the drive source based on the tightening torque.

Abstract: The present invention relates to a method for tightening a bolt connection through elongation of the bolt where strokes of a power element, especially a hydraulic cylinder, are converted into a rotational movement of a tightening tool. The method according to an embodiment of the present invention is carried out in at least two steps. As a first step, the bolt is first tightened to a predetermined snug torque. As a second step, the bolt is then tightened up through a predetermined number of complete strokes of the power element of the power wrench. In this way, a torque method is combined with a rotational angle method that is controlled by the number of strokes.

Abstract: There is described a torque tool comprising a synchronous reluctance motor. The torque tool comprises an electrical machine drive system, an electronic controller and a gear system. The drive system comprises a rotor and a stator arranged around the rotor. The rotor is attached to a motor shaft and comprises a pattern of regions of relatively high magnetic permeability interspersed with regions of relatively low magnetic permeability extending generally parallel to the motor shaft such that there is a plurality of magnetic poles distributed circumferentially around the motor shaft. The stator comprises electrical windings dispersed in slots disposed around an inner surface of the stator, the slots extending generally parallel to the motor shaft such that, when current flows in the windings, a stator magnetic field generated by the current has the same number of magnetic poles as the rotor.

Abstract: An improved method is provided for operating a power tool. The method includes receiving an input control variable from an input unit; receiving at least one tool parameter relating to the power tool; determining a derivative of the input control variable; selecting one of a plurality of control profiles based on the control input variable, the derivative of the input control variable, and the tool parameter, each control profile correlating the control input variable of the input unit to a rotational speed at which to drive the output shaft; and driving the output shaft at a rotational speed in accordance with the selected control profile.

Abstract: An improved method is provided for operating a power tool. The method includes receiving an input control variable from an input unit; determining a second derivative of the input control variable; selecting one of a plurality of control profiles based on the control input variable and the second derivative, each control profile correlating the control input variable of the input unit to a rotational speed at which to drive the output shaft; and driving the output shaft at a rotational speed in accordance with the selected control profile.

Abstract: A power tool includes a housing, a motor, an output member driven by the motor, and a reaming attachment coupled to the output member. The reaming attachment has a front end portion selectively driven in rotation by the output member to drive a fastener into a workpiece, and a reaming portion selectively driven in rotation by the output member to remove material from an end surface of a conduit. A rotational motion sensor in the housing is operable to detect rotational motion of the housing about an axis. A controller receives a signal indicative of rotational motion from the sensor, determines a direction of the rotational motion of the housing, and drives the motor in a direction corresponding to the direction of rotational motion of the housing.

Abstract: A torque applying system includes a torque applying tool having a motor and rotating output spindle, a torque sensor that measures an instantaneous torque exerted by the output spindle during a fastening cycle, and a controller operatively connected to the tool to control the tool's rotational speed during the fastening cycle. The controller is programmed to control the tool's rotational speed to be [(?F??C)/t]/r, wherein t is a time constant of speed control, ?F is a target final torque for the fastening cycle, and r is a torque rate.

Abstract: A rotary impact tool includes: a hammer rotating by receiving a rotational force of a motor; an anvil rotating by receiving a rotational force of the hammer; and an end tool attached to the anvil, the rotary impact tool being constructed such that when a torque of a value not less than a predetermined value is applied to the anvil from the outside, the hammer is disengaged from the anvil to rotate idle and applies an impact to the anvil in a rotational direction after rotating idle by a predetermined angle, the rotary impact tool including an impact detector configured to detect impacts and a speed switching device configured to switch the rotational speed of the motor, and when the impact detector detects an impact during rotation of the anvil in a tightening direction, the speed switching device switches the rotational speed of the motor from a normal speed to a low speed.

Abstract: A power tool has an electric motor driving a spindle and a rotary encoder for setting a torque limit. A control circuit is operatively connected to the rotary encoder for interrupting power supply to the motor when the torque limit has been reached. An actuator sleeve mounted to rotate about the spindle, and a detent holds the sleeve in a plurality of angular positions corresponding to positions of the contacts.

Abstract: A power tool having an electric motor with a static stall torque and a housing, a tool holder being mounted on the housing rotatably about an axis of rotation, the electric motor being connected to the tool holder, a handle for an operator being provided on the housing, the handle having a handle length, characterized in that the ratio of the static stall torque to the handle length is greater than 400 Nm/m.

Abstract: A safety apparatus for a portable tool having an internal combustion engine has at least one accelerometer providing a measurement of an acceleration of the portable tool in at least one plane or axis. An electronic controller is connected to an output of the accelerometer so as to receive analog or digital information. A generator is driven by the internal combustion engine so as to supply power to the accelerometer. A management card processes the analog or digital information so as to activate the system acting on an ignition exciter box so as to nearly instantaneously stop the internal combustion engine when the acceleration of the portable tool exceeds a predetermined level.

Abstract: An electric assembly device for tightening of fastener includes a housing and a rotation. motor which is drivingly connected to an output shaft. The output shaft has a forward portion extending out of the housing, and is adapted to carry a coupling device for releasable coupling with a fastener during tightening, which is to be performed along a first rotation axis. The device is adapted to determine an angular displacement of the housing with respect to the first rotation axis during tightening of the fastener, and to control the rotation speed of the motor during tightening based on the determined angular displacement of the housing.

Abstract: An improved method is provided for operating a power tool. The method includes: monitoring rotational motion of the power tool about an axis using a rotational motion sensor disposed in the power tool; determining a direction of the rotational motion about the axis; and driving the output member in a direction defined by the detected rotational motion of the tool, where the output member is driven by a motor residing in the power tool. Thus, the output member is drive clockwise when the rotational motion of the tool is clockwise about the axis and the output member is drive counter-clockwise when the rotational motion of the tool is counter-clockwise about the axis.

Abstract: A wireless communications system includes a tool having a first wireless communications unit and a transceiver having a second wireless communications unit to receive a signal transmitted from the first wireless communications unit. Further, the transceiver has a setting unit for setting wireless communications parameters for wireless communications between the first and the second wireless communications unit, and the tool has a tool control unit for setting in the wireless communications unit the wireless communications parameters set by the setting unit and transmitted to the tool by wireless communication.

Abstract: An improved method is provided for operating a power tool. The method includes receiving an input control variable from an input unit; determining a derivative of the input control variable; selecting one of a plurality of control profiles based on the control input variable and the derivative, each control profile correlating the control input variable of the input unit to a rotational speed at which to drive the output shaft; and driving the output shaft at a rotational speed in accordance with the selected control profile.

Abstract: According to an aspect of the present invention, there is provided a rotary striking tool, including: a motor; an impact unit having a driving part being driven by the motor and an output part; a tip-tool side output shaft that is coupled to the output part; an impact detection unit that detects an impact generated at the impact unit; and a control unit programmed to: control the impact unit to perform a confirmation striking when the impact detected by the impact detection unit reaches a prescribed value, detect a rotation angle of the output shaft at the confirmation striking, determine whether a fastening operation is completed when the detected rotation angle is equal to or smaller than a predetermined angle, and continue the fastening operation when the detected rotation angle is larger than the predetermined angle.

Abstract: A power tool includes an output shaft configured to rotate about a longitudinal axis, a motor drivably connected to the output shaft to impart rotary motions thereto, and a rotational motion sensor spatially separated from the output shaft and operable to determine the user-imparted rotational motion of the power tool with respect to the longitudinal axis. A controller is electrically connected to the rotational motion sensor and the motor. The controller determines angular velocity of the power tool about the axis, rotational displacement of the power tool about the axis, and/or a direction of the rotational displacement using input from the rotational motion sensor. The controller then controls the motor according to the angular velocity, the rotational displacement, and/or the direction of the rotational displacement.

Abstract: A discontinuous drive power tool assembly for generating rotational torque includes a spindle having a first end portion and a second end portion. The first end portion of the spindle is configured to engage and rotate an object. The tool assembly also includes a pulse hammer selectively engagable with the second end portion of the spindle, and a motor that includes a motor shaft engagable with the pulse hammer. The motor is configured to rotate the pulse hammer. The tool assembly also includes a rotational position sensor disposed adjacent the motor. The rotational position sensor is configured to measure the rotational position of a second portion of the motor shaft which is opposite the first end portion of the motor shaft during operation of the tool assembly.

Abstract: An improved method is provided for controlling a power tool having a rotary shaft. The method includes: disposing an inertial mass in a housing of the power tool, such that the inertial mass is freely rotatable about an axis of rotation which is axially aligned with the rotary shaft; monitoring rotational motion of the power tool in relation to the inertial mass during operation of the power tool; and activating a protective operation based on the rotational motion of the power tool in relation to the inertial mass.

Abstract: The present invention has disclosed a variable speed tool and a variable speed control method. The tool includes a switch; a gearbox housing; a motor; an outputting shaft; a multistage transmitting gear train and a gearshift ring which are mated with the motor and the outputting shaft, the gearshift ring having inner teeth; a gearshift fork mated with the gearshift ring; a tension spring arranged between the gearbox housing and the gearshift fork; and a torque sensing ring provided with a sliding groove in which the gearshift fork is movably disposed. When the load of the outputting shaft has reached to a predetermined value, the torque sensing ring makes the gearshift fork move axially in the sliding groove under the action of the tension spring, thus bringing the gearshift ring to move axially. The variable speed tool of the present invention may automatically adjust the rotating speed and the torque of the outputting shaft according to a variation of the load torque.

Abstract: An improved method is provided for controlling a power tool having a rotary shaft. The method includes: disposing an inertial mass in a housing of the power tool, such that the inertial mass is freely rotatable about an axis of rotation which is axially aligned with the rotary shaft; monitoring rotational motion of the power tool in relation to the inertial mass during operation of the power tool; and activating a protective operation based on the rotational motion of the power tool in relation to the inertial mass.

Abstract: A tightening tool for tightening a fastener is disclosed which comprises a motor and a main shaft that engages with the fastener. A clutch is disposed between the motor and the main shaft so that the clutch rotates the main shaft by transmitting torque from the motor to the main shaft when a load acting on the main shaft is less than a predetermined value. The clutch shuts off torque transmission from the motor to the main shaft when the load acting on the main shaft reaches or exceeds the predetermined value. When in use, the current flowing to the motor and rotation angle of the main shaft of the motor are detected. The detected current and rotation angle are used to determine whether the tightening torque of the fastener is normal.

Abstract: The present invention has disclosed a variable speed tool and a variable speed control method. The tool includes a switch; a gearbox housing; a motor; an outputting shaft; a multistage transmitting gear train and a gearshift ring which are mated with the motor and the outputting shaft, the gearshift ring having inner teeth; a gearshift fork mated with the gearshift ring; a tension spring arranged between the gearbox housing and the gearshift fork; and a torque sensing ring provided with a sliding groove in which the gearshift fork is movably disposed. When the load of the outputting shaft has reached to a predetermined value, the torque sensing ring makes the gearshift fork move axially in the sliding groove under the action of the tension spring, thus bringing the gearshift ring to move axially. The variable speed tool of the present invention may automatically adjust the rotating speed and the torque of the outputting shaft according to a variation of the load torque.

Abstract: Apparatus (25) for determining when a fastener has been tightened to a predetermined tightness level by an impact wrench (1) comprises determining the number of hammer impacts to advance an anvil (9) of the impact wrench (1) through a predetermined angle and comparing the number of hammer impacts with a predetermined number of hammer impacts. Initially, the cumulative angular displacement of the anvil (9) from the first detected hammer impact is determined from the cumulative angular position of the hammer (5) for the corresponding hammer impact from the first detected hammer impact. The cumulative angular displacement of the hammer (5) is determined when the rotational speed of the hammer (5) is zero, at a minimum or approaching zero just prior to the direction of rotation of the hammer (5) reversing at the corresponding hammer impact.

Abstract: A tightening tool for tightening a fastener is disclosed which comprises a motor and a main shaft that engages with the fastener. A clutch is disposed between the motor and the main shaft so that the clutch rotates the main shaft by transmitting torque from the motor to the main shaft when a load acting on the main shaft is less than a predetermined value. The clutch shuts off torque transmission from the motor to the main shaft when the load acting on the main shaft reaches or exceeds the predetermined value. When in use, the current flowing to the motor and rotation angle of the main shaft of the motor are detected. The detected current and rotation angle are used to determine whether the tightening torque of the fastener is normal.

Abstract: A lifting device such as a mobile crane having a main body and a boom, such as a lattice boom, for supporting a pile lead for, e.g., pile driving or continuous flight auger drilling, and a method of using same. A hydraulically operated mechanical spotter arm may be attached between the device body and the pile lead. Electronic position sensors on the spotter arm may be used to measure angular relationships between the pile lead and the spotter arm. Position sensors on a boom box on the boom may also be used. When the pile lead is swung, information from the sensors may be used by an electronic control system to automatically maintain the pile lead in a desirable position, limiting torque induced in the boom. The boom box position sensors may be used to counter-steer the spotter arm to further limit torque. The boom box may also be fitted with rubber springs to permit controlled pile lead deflection while limiting load transmitted to the boom.

Abstract: A fastening tool with a clutch for shutting off transmission of torque, capable of self-diagnosing fastening torque of a screw or the like at low cost without using expensive elements such as a torque sensor, etc. A fastening tool (10) has a motor (13), a main shaft (20) engaging with a screw or the like, and a clutch (14) interposed between the motor (13) and the main shaft (20). The clutch (14) transmits torque from the motor (13) to the main shaft (20) when a load acting on the main shaft (20) is less than a predetermined value, and shuts off torque transmission from the motor (13) to the main shaft (20) when a load acting on the main shaft (20) is equal to or greater than the predetermined value. The fastening tool (10) further has a control unit (60) for controlling the motor (13).

Abstract: The invention proposes a method for controlling the tightening angle of screwed joints when tightening is effected using a hand-held screwing tool, wherein the torque is monitored until a predefined threshold value is reached, the angle of rotation is measured from the point the threshold value has been reached, the relative rotation of the screwing tool relative to the screwed joint is measured from the point the threshold value has been reached, and the screwing tool is switched off when a predetermined angle of rotation is reached, taking into account the relative angle of rotation of the screwing tool relative to the screwed joint as a corrective value.

Abstract: An improved method is provided for controlling a power tool having a rotary shaft. The method includes: disposing an inertial mass in a housing of the power tool, such that the inertial mass is freely rotatable about an axis of rotation which is axially aligned with the rotary shaft; monitoring rotational motion of the power tool in relation to the inertial mass during operation of the power tool; and activating a protective operation based on the rotational motion of the power tool in relation to the inertial mass.

Abstract: An improved method is provided for controlling a power tool having a rotary shaft. The method includes: disposing an inertial mass in a housing of the power tool, such that the inertial mass is freely rotatable about an axis of rotation which is axially aligned with the rotary shaft; monitoring rotational motion of the power tool in relation to the inertial mass during operation of the power tool; and activating a protective operation based on the rotational motion of the power tool in relation to the inertial mass.

Abstract: A method and a power tool system are provided for performing screw joint tightening using a pneumatic torque impulse power tool that is controlled by a control unit. A torque magnitude and a torque growth are calculated based on signals delivered by an angle sensor, and pressurized air is supplied to the power tool via a flow regulating valve which is successively adjustable between zero and full power flow. The flow regulating valve is controlled by the control unit to deliver a reduced power air flow to the power tool before and during a first delivered impulse, and then to deliver full power flow until a certain torque magnitude or a percentage of a target torque level is reached, whereafter the air supply flow is again reduced until the target torque level is reached, and when the target torque level is reached the air flow is shut off.

Abstract: In an impulse wrench there is provided an impulse unit with a motor driven inertia drive member, and a movement detecting device arranged to detect an angular movement of the inertia drive member. The movement detecting device includes a rotating disc rigidly connected to and co-rotating with the inertia drive member. The impulse wrench also includes a sensing device including four Hall-element type sensors, and the disc has a rim portion which is magnetised to provide a number of magnetic poles for activating the sensors at rotation of the inertia drive member. The sensors are arranged in pairs such that the delivered signals from the sensors in each pair has a relative phase lag of 180 degrees, and the sensors of one of the pairs are arranged to deliver signals with a phase lag of 90 degrees relative to the sensor signals from the other pair.