Abstract: A powered threaded rod cutter includes first and second cutting dies, an electric motor, a planetary transmission positioned downstream of the motor, a drivetrain for converting a rotational output of the transmission to a pivoting movement of the first cutting die, and a clutch mechanism for redirecting torque from the motor away from a drivetrain and the first cutting die in response to the first cutting die seizing during a rod-cutting operation. The clutch mechanism includes a ring gear in the planetary transmission, and a spring that rotationally affixes the ring gear below a predetermined threshold of reaction torque through the drivetrain and permits rotation of the ring gear above the threshold.

Abstract: The disclosure relates to a method for controlling a motor of a hand-held power tool by means of a blockable operating element, wherein a first position and a second position of the operating element are ascertained. According to the disclosure, the motor remains deactivated if a deviation of the ascertained first position from the ascertained second position is less than a threshold value.

Abstract: A power tool includes a housing. A motor is housed in the housing. A platen is driven by the motor. The housing includes a first housing part, a second housing part and a third housing part. The housing defines a battery receptacle portion configured to receive a removable battery pack which powers the motor. Each of the first housing part, the second housing part and the third housing part form part of the battery receptacle portion.

Abstract: An impact tool includes a switch for driving the tool accessory, an operation member configured to be movable between an OFF position and an ON position, a first lock member configured to lock the operation member in the ON position, a second lock member configured to be movable between a lock position and a lock-release position in response to an external operation by a user, and a holding mechanism configured to hold the second lock member in the lock position and also in the lock-release position. The second lock member in the lock position is capable of locking the operation member in the OFF position, and the second lock member in the lock-release position is incapable of locking the operation member in the OFF position.

Abstract: An electrical sander structure has a main body, a control mechanism and a control circuit. The main body has a brushless motor, and an electromagnetic coil in the brushless motor has a slotted concentrated winding brushless DC motor design. The control circuit is further includes a power detecting module, a rated power constraint module, an intelligent temperature control protection module and a rotation control module. The brushless motor is able to adjust the speed according to the load variations and intelligent temperature control protection mechanism, maintain the optimal operating efficiency and continuously operate within the power set by the rated power limit. In turn, the brushless motor can operate at optimum operating efficiency, helping to extend the life of the brushless motor, increasing user productivity and reducing energy losses.

Abstract: An impact tool includes a housing, an electric motor supported in the housing, and a drive assembly for converting a continuous torque input from the motor to consecutive rotational impacts upon a workpiece capable of developing at least 1,700 ft-lbs of fastening torque. The drive assembly includes an anvil rotatable about an axis and having a head adjacent a distal end of the anvil. The head has a minimum cross-sectional width of at least 1 inch in a plane oriented transverse to the axis. The drive assembly also includes a hammer that is both rotationally and axially movable relative to the anvil for imparting the consecutive rotational impacts upon the anvil, and a spring for biasing the hammer in an axial direction toward the anvil.

Abstract: An electric power tool includes a bearing retainer that retains a bearing for supporting a motor shaft, a transmission mechanism that transmits a rotational output of a motor to a front-end tool and a rotating body attached to an end of the motor shaft. The bearing retainer includes an extension that extends in a direction of axial line from an end face position on the bearing. At least a part of the rotating body is provided in front of a rear end of the extension.

Abstract: A screw driving includes a housing, a motor, a spindle, a locator, a first detecting mechanism and a controller. The locator is mounted on a front end portion of the housing so as to be movable in a front-rear direction relative to the housing and configured to define a depth to which a screw is driven into a workpiece. The first detecting mechanism is configured to detect a position of the locator in the front-rear direction. The controller is configured to control driving of the motor. Rotational driving of the spindle in a forward direction is started in response to the spindle being pressed rearward, and the rotational driving of the spindle in the forward direction is stopped when the first detecting mechanism detects that the locator is disposed in a specified position rearward of a most forward position within a moving range of the locator.

Abstract: A pneumatic hammer has a handle, a body, a valve seat, a cylinder device, an assembling device, and a chisel. The body is transversally connected to the handle and has a chamber. The valve seat is mounted in the chamber of the body and has a rear valve, a front valve, and a valve plate disposed between the rear valve and the front valve. The cylinder device is mounted in the chamber, abuts against the valve seat, and has a cylinder barrel and a hammer. The cylinder barrel is mounted in the chamber and has a cylinder chamber. The hammer is movably disposed in the cylinder chamber. The assembling device is connected to the cylinder device, and has a mounting jacket, an engaging element, multiple positioning elements, a spring, and an engaging ring. The chisel is detachably connected to the assembling device, and is inserted into the cylinder chamber.

Abstract: A fastener driving tool magazine and nose piece for use with a fastener with a preinstalled elastomer beneath the head of the fastener. A magazine structure for avoiding damage to the elastomer is taught and a birds beak fastener guide is taught for installing the fastener while still avoiding damage to the elastomer.

Abstract: A hammer/drill includes a housing, a motor with armature shaft, a spindle rotatably mounted about a longitudinal axis in the housing, a tool holder rotatingly driven by the motor about the longitudinal axis, a hammer mechanism for generating impacts acting on the tool holder, a drive shaft coupleable with the armature shaft, and a switching arrangement to switch between drilling, hammer drilling, and hammering modes. The switching arrangement comprises a selector and coupling part axially displaceable on the drive shaft between lower and upper positions, coupling and decoupling the drive shaft to the armature shaft respectively. The coupling part includes a sleeve comprising a flange, and the selector comprises a fork for engaging a lower part of the flange. A protuberance engages a drive member of the selector to pivot the selector when the spindle is rotated, engaging over only a portion of the rotational movement of the spindle.

Abstract: A drill bit includes a bit body; a pad associated with the bit body; and a rate control device coupled to the pad that extends from a bit surface at a first rate and retracts from an extended position to a retracted position at a second rate in response to external force applied onto the pad. The rate control device includes a piston for applying a force on the pad; a biasing member that applies a force on the piston to extend the pad at the first rate; a fluid chamber associated with the piston; and a pressure management device for controlling a fluid pressure within the fluid chamber.

Abstract: A drill bit includes a bit body; a pad associated with the bit body; a rate control device coupled to the pad that extends from a bit surface at a first rate and retracts from an extended position to a retracted position at a second rate in response to external force applied onto the pad. The rate control device includes a piston for applying a force on the pad; a biasing member that applies a force on the piston to extend the pad at the first rate; a fluid chamber associated with the piston; and a pressure management device for controlling a fluid pressure within the fluid chamber.

Abstract: A drill bit and a method of drilling a wellbore utilizing the drill bit is disclosed. The method includes providing a drill bit including a bit body and at least one movable member associated with a lateral extent of the bit body. The method further includes conveying a drill string into a formation, the drill string having the drill bit at the end thereof and drilling the wellbore using the drill string. During drilling, the drill bit can selectively extend the at least one moveable member from the lateral extent of the bit body at a first rate and selectively retract the at least one moveable member to a retracted position at a second rate that is less than the first rate.

Abstract: A directional drilling system consisting of a four-motor drilling head for better steering in directional drilling and vertical/horizontal drilling is developed. The rotational speed of each motor is independently controlled. The use of four motors in coordination with other traditional drilling variables allow precise control of the drilling direction and optimization of the rate of penetration (ROP). The top and right motors rotate in opposite directions to the bottom and left rotors to stabilize the roll rotation of the drilling head. Inclination (pitch) movement is obtained by increasing/decreasing the speed of the top motor while decreasing/increasing the speed of the lower motor. The Azimuth (yaw) movement is obtained similarly using the right and left motors. The drilling power is derived from down hole motors. A drill string transmits the drilling fluid and force on bit.

Abstract: A pneumatic motor with built-in striker mechanism mainly includes a cylinder, rotor set and output shaft lever. The rotor set has a rotary drum and flexible blades. The output shaft lever can be driven by the rotary drum. A chamber is formed into the rotary drum and a striking portion on the output shaft lever is located within the chamber. The built-in striker mechanism is placed in the chamber and has striking bulges protruded on the striking portion, movable hammers sleeved externally on the striking bulge and struts axially located on the rotary drum. This new pneumatic motor has the striker mechanism set into the rotary drum of the rotor set, thus reducing greatly the axial length and volume of the pneumatic motor and realizing ease-of-use.

Abstract: A drywall screwdriver includes a housing, an element delimiting the depth of engagement, a drive unit, an outlet spindle, and a planetary gear that comprises at least one hollow wheel. The drywall screwdriver further comprises at least one support element that is different from a housing element and that at least partially surrounds the ring gear of the planetary gear.

Abstract: A drill bit including a bit body and a pad. The pad extends from a retracted position to an extended position from a bit surface at a first rate and retracts from the extended position to a retracted position at a second rate that is less than the first rate.

Abstract: A screw driver (100) which comprises a motor (110) and a rotation transmission mechanism (120) is provided. The rotation transmission mechanism (120) comprises a driving gear (125), a spindle (150), a roller (141) and a retainer (130). The retainer (130) moves the roller (140) in a circumference direction of the spindle (150) and thereby a position of the roller (140) between a transmittable position and a non-transmittable position is switched.

Abstract: A lock state occurrence determination apparatus includes a counter, a reset device, a reference time changing device, a lock state determination device, and an invalidation device. The invalidation device performs, in a case where a false determination of occurrence of a lock state of a motor is caused by the lock state determination device due to an operation input to operate a rotation speed of the motor, at least one of a first invalidation operation to invalidate the lock state determination device and a second invalidation operation to invalidate continuation of a counting operation by the counter.

Abstract: A handheld power tool has a tool holder for holding a tool, and a grip housing for holding and guiding the handheld power tool. A relative motion of the tool holder and the grip housing can be transmitted as a switching motion to a microswitch, which switches a drive unit on and off. The tool holder and the grip housing can be moved relative to one another in a direction of rotation, and the switching motion thus comprises a rotary motion of the grip 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 screw driver capable of stably stopping a bit to stabilize fastening depth of a screw. The screw driver includes a rotary portion, a housing, and a clutch mechanism. The rotary portion is rotated by a power source and has a bit engageable with a screw. The rotary portion also has a moving portion holding the bit and movable between a top dead center and a bottom dead center in an axial direction of the rotary portion. The housing rotatably supports the rotary portion. The clutch mechanism includes a first clutch plate unrotatable relative to the housing, and a second clutch plate movable in the axial direction and rotatable integrally with the rotation of the rotary portion. The first and second clutch plates are positioned to be urged by the moving portion and pressed together when the moving portion reaches the bottom dead center.

Abstract: A medical or dental, fluid-driven handle with a control or regulation circuit for the limiting, control or regulation to a maximum or predetermined rotational speed and a corresponding process are presented. The handle comprises a rotary part that can be set in rotary motion by a drive fluid, a fluid line carrying the drive fluid to or from the rotary part or a fluid branch line that is connected to a fluid line carrying drive fluid, and a control or regulation circuit designed to limit, control or regulate the rotational speed of the rotary part. An electrodynamic converter is driven by the rotary part for generating electrical energy and at least one actuator element is configured to act on the drive fluid. The actuator element is electrically connected to the electrodynamic converter such that it is supplied with electrical energy generated by the electrodynamic converter.

Abstract: A pneumatic device control apparatus and method comprising a ported valve slidably fitted over a feed tube of the pneumatic device, and using a compliant biasing device to constrain motion of the valve to provide asymmetric timing for extended pressurization of a power chamber and reduced pressurization of a return chamber of the pneumatic device. The pneumatic device can be a pneumatic hammer drill.

Abstract: A fluid distributor cylinder is for a percussive drill assembly that includes a casing having an inner circumferential surface defining a central bore, a central axis extending through the bore, a bit movably coupled with the casing and a piston movably disposed within the casing bore. The distributor cylinder includes a generally tubular body disposeable within the casing bore and having first and second ends, a central axis extending generally between the first and second ends, an outer circumferential surface. At least a section of the outer surface is configured to engage with the inner surface of the casing so to form an interference fit between the body and the casing. The cylinder includes an exterior thread and/or a radially-extending shoulder configured to releasably engage with the casing inner surface so as to substantially prevent axial displacement of the distributor body with respect to the casing.

Abstract: A hammering tool includes, within its tool main body, a piston which reciprocates by using a motor as its drive force, a hammering member which carries out its hammering operation in linking with the reciprocating motion of the piston, and an intermediate member which transmits a hammering force of the hammering member to a top end tool mounted on the top end of the tool main body. The tool main body further includes a measuring device which measures a hammering state of the hammering member and a control device which controls the number of rotations of the motor. The control device, according to measurement results of the measuring device, determines the limit number of times of hammering where the hammering member becomes unable to follow the reciprocating motion of the piston, and thus controls the number of rotations of the motor.

Abstract: A driver for an inflatable rotating exhibit is mounted inside an inflatable rotating exhibit having a transparent inflatable body and a rotating body and has a rotating assembly and a reverse-rotation preventer. The rotating assembly connects to and rotates the rotating body, has a synchronous motor. The synchronous motor rotates in a direction and has a shaft. The shaft is driven by the synchronous motor and rotates the rotating body. However, the synchronous motor will reverse its rotation when the rotating body encounters even temporary resistance while rotating. The reverse-rotation preventer applies a resistance when the rotating body rotates in the wrong direction to make the synchronous motor reverse rotation again to the desired direction. So the reverse-rotation preventer ensures that the rotating inflatable exhibit rotates in the desired direction.

Abstract: A pneumatic hammer comprises an elongate hollow casing with operatively upper and lower ends and has a piston slidingly received within the casing and operable to reciprocate within the casing between upper and lower pressure chambers defined within the casing. The hammer further has an axially displaceable bit assembly at the lower end of the casing and a backend assembly at the upper end of the casing. The piston has a striking face at an end thereof proximate the bit assembly, and the piston is operable to impact on a contact surface of the bit assembly in an impact region of the casing. The hammer is characterized in that the piston is shaped and dimensioned at its proximal end to have a snug sliding fit with an interior of the casing in the impact region of the casing.

Abstract: A pressure regulating mechanism for use in a pneumatic tool includes a first relief valve and a second relief valve. The pneumatic tool includes a housing having an air intake passage, an exhaust passage and a connecting passage in air communication between the air intake passage and the exhaust passage, an air cylinder unit mounted in the housing. The air cylinder unit has an air chamber, an air passage in air communication between the air chamber and the air intake passage, and a through hole in air communication with the air passage. The first relief valve is for mounting in the connecting passage adjacent to the air cylinder unit. The second relief valve is for mounting in the through hole of the air cylinder unit. The pressure regulating mechanism maintains the air pressure inside the pneumatic tool stable.

Abstract: A representative screwdriver may comprise a motor, a body, a first spindle, a first clutch member, a tool bit, a second spindle, a second clutch member, a clutch engagement preventing member. The representative screwdriver may be selectively operated in one of a first power transmission mode and a second power transmission mode. In the first power transmission mode, the first clutch member and the second clutch member are disengaged when the reaction torque applied from the work-piece onto the tool bit exceeds a predetermined torque. In the second power transmission mode, the first clutch member and the second clutch member are disengaged when the tool bit moves a predetermined distance away from the body toward the work-piece during the screw-tightening operation. According to the representative screwdriver, the engagement and disengagement of the clutch members during the screw-tightening operation can be assuredly performed in both the operation modes.

Abstract: A trigger controller for an electric power tool including a motor and a pull-trigger movable along a path having a foremost home position comprises a mechanical switch and a solid-state switch connected in series to the motor, wherein the mechanical switch includes a first moving contact, and the controller includes a second moving contact wherein the first and second moving contacts are movable to operate the mechanical and solid-state switches respectively at different predetermined travelling positions of the pull-trigger from the home position such that the two switches are caused to be initially closed at different times.

Abstract: The invention is based on a hand power tool comprising a striking element via which a tool (10) in a tool holder (12) can be driven in striking fashion, which said tool holder can be detachably secured—via its body (14)—to a drive part (16) via at least one locking element (18), which said locking element, in its engaged position, is capable of being fixed in position radially by a retaining element (20), which said retaining element is capable of being guided by means of an operating element (22) out of its locked position into a release position that radially releases the locking element (18) in order to release the tool holder (12), whereby the retaining element (20) is capable of being moved by a corresponding component (14) into its release position against a spring force of a spring element (24) when the tool holder (12) is pushed onto the drive part (18).

Abstract: A cutting blade is provided for a reaper which can easily position members to be welded, can reduce a welding distortion, can fully ensure the strength of a shank member and can easily be manufactured. The cutting blade comprises a bar-shaped shank member having axially extending grooves formed on an outer peripheral face of a tip portion and having a base end to be fixed to the reaper, and a plate-shaped blade member having a notch portion formed on a base end, wherein the tip portion of the shank member is fitted in the notch portion of the plate-shaped blade member in such a manner that edge portions of the notch portion are fitted in the grooves, and the fitted tip portion of the shank member is welded to a portion of the plate-shaped blade member which is located around the tip portion.

Abstract: A rotary impacting apparatus is provided that includes a housing, a rotor rotatable about an axis, a main reciprocative implement and an impact member. The impact member is arranged to exert an impacting force on the main reciprocative implement when the main receprocative implement is advanced relative to the axis. The rotor is supported by the housing via needle bearings.

Abstract: When a start SW 3 is pressed, a one-shot multivibrator circuit 15 turns on and releases a pulse. The pulse is transmitted to a self-hold circuit 16 which in turn stays in self-hold mode and releases an H level output continuously until it is reset. This cause a transistor 17 to turn on and actuate a ram downward movement relay R1. When the ram arrives at the lower limit of its movement, a lower LS 4 is opened causing a self-hold circuit 21 to produce an H level signal in accordance with an output of a one-shot multivibrator 18. The H level signal from the self-hold circuit 21 is delayed by a delay circuit 22 and turns on a transistor 23. As the result, a ram upward movement relay R2 is actuated. Because of the function of the one-shot multivibrator circuit 15, the ram will not restart when the start SW 3 is continuously depressed. The delay circuit 22 contributes to the longer operational life of a directional valve switching mechanism.

Abstract: An improved fluid actuated percussive impact tool of the valveless type adapted for down hole drilling is provided. The impact tool includes a casing, a back head, a distributor located at a first end of the casing, and an impact receiving device located at a second end of the casing. A chamber is located between the distributor and the impact receiving device. A cylinder sleeve is located in the chamber adjacent to the distributor. A first pressurized fluid passage is located between the casing and the cylinder sleeve for passing pressurized fluid from the distributor to the chamber. A piston is located in the chamber for reciprocating axial movement. Axially extending ports are located on at least one of the piston, the cylinder sleeve and the casing in the chamber for alternately supplying pressurized fluid to upper and lower chamber portions.

Abstract: A hand tool (1) having a drive motor (12), a depth stop (16) by which the drive motor (12) can be automatically switched off when it is in contact with a workpiece (4), and a switching mechanism (21) in an electric circuit (22). The electric circuit (22) includes a switch (24) for switching the drive motor (12) on and off, a first contact element (25) for reversing the polarity of the drive motor (12) and a second contact element (26) for switching off the drive motor (12) by the use of the depth stop (16).

Abstract: The invention provides an In-The-Hole hydraulic drive unit for rotating a rock drill. A hydraulic motor having a fixed rear trailing end and a rotating front drilling end converts hydraulic power into a rotational drive force. The hydraulic motor receives high pressure hydraulic fluid through a receiving inlet and discharges lower pressure hydraulic fluid through a hydraulic outlet. A drive shaft connected to the rotating front drilling end is disposed within the hydraulic motor. A fluid transfer conduit within the drive shaft transfers hydraulic or pneumatic drill fluid to power the rock drill. The fluid transfer conduit bypasses the hydraulic motor for independent supply and operation of the rock drill. The fluid transfer conduit receives the drill fluid from the surface and transfers the drill fluid toward the rock drill. The drive shaft contains a drill rotator attached to the front drilling end adapted to receive and rotate the rock drill.

Abstract: A pneumatic hammer comprises a rigid unit of construction, which comprises a housing, a handle, an operating cylinder resiliently supported in the housing, and a tool holder for receiving a tool movable in a striking direction by the operating cylinder. The operating cylinder is axially movable in the housing relative to the tool holder. Compressed air is supplied to the operating cylinder, and a damping spring acts upon the tool holder in a direction opposite to the striking direction.

Abstract: A latching magnetic switch is utilized to activate a push to start nutrunner or the like wherein the magnetic latching switch is deactivated first by one magnetic pole and thereafter upon engagement with the work piece and compression of the spindle and opposite pole of the magnet is utilized to activate the tool.

Abstract: A vibration dampened percussive tool has a handle assembly and a cover surrounding a barrel and piston assembly which are caused to oscillate relatively to the handle assembly. The barrel assembly receives a tool retainer and a trigger controls primary air supply. To reduce air consumption when the tool is not actually applied to a workpiece and thereby to reduce exposure of the operator's hand/arm to vibration, an air metering device is provided, which includes a tube slidably mounted in a bush and having a bleed hole in an end of the tube which enters the bush. In one position of the tube within the bush, apertures in the tube are sealed to allow the tool idle and in another position of the tube the apertures are exposed. The tube connects the air line with the piston assembly and moves within the bush responsive to pressure applied by the actual tool on the workpiece.

Abstract: A rotary impacting apparatus comprises a housing, a rotor rotated in the housing, an impact member eccentrically held by the rotor, and a main reciprocative implement held reciprocatively at a forward end portion of the housing. The rotor rotates to hit the impact member for driving the main reciprocative implement into the ground for instance. The apparatus further includes an auxiliary oscillating mechanism for transmitting an impacting force from the impact member to pull the main reciprocative implement when the housing is pulled relative to the main reciprocative implement by a predetermined distance.

Abstract: A hammer of the type having an impact tool driven by pressurized fluid has a hammer body portion with a closed rearward end and an open forward end and a piston longitudinally movably housed within the hammer body portion for striking a tool mounted at the open forward end of the hammer body portion, to thereby impact an object with the tool. The hammer has a fluid valve housed within the closed rearward end of the hammer body portion rearwardly of the piston and in communication with a source of high pressure fluid for driving the piston. The fluid valve has a valve body portion defining an interior chamber and a continuous exterior side wall, and a longitudinal opening in communication with the interior chamber. The valve body has a first body portion and second body portion which is identical to the first body portion and positioned longitudinally in relation thereto within the closed rearward end of the hammer body portion.

Abstract: A battery type screw driver has an auxiliary switch 39 in addition to a main switch 37. A clutch 30 is provided between a driving shaft 16 and a driven shaft 11. A central bore 32 is formed along the central axis of the driving shaft 16. The operation bar 33 passes through the bore 32. A front end part of the operation bar 33 is connected to the driven shaft 11, while a rear end part thereof protrudes backwardly of the driving shaft 16. An auxiliary switch 39 is disposed in series with the main switch 37 in an electric circuit between the motor 8 and a battery 35. The auxiliary switch 39 is turned on when depressed by the operation bar 33 sliding backward when the screw 24 is fastened. The operation bar slides coaxially with the central axis of the driving shaft.

Abstract: The invention is a safety mechanism for an air-powered tool. The mechanism senses the position of the tool's implement retainer and disables the air flow to the tool's motor if the retainer is not in its locked position. The mechanism employs a pushrod that has one end adapted to contact a rear surface of the retainer when the retainer is in its lock position. The other end of the pushrod is adapted to contact a spring-biased ball-type check valve located within the air inlet to the tool's motor. When the retainer is removed from the tool, the pushrod moves forwardly under the urging of the valve and at the same time allows the valve to move to its closed position to thereby prevent any flow of pressurized air to the motor.

Abstract: To improve a power-operated screwing tool machine comprising a drive arranged in a housing, a screwing tool and a switch-off means for the screw-in depth including a depth stop held on the housing for fixing a screw-in depth and a clutch arranged between the drive and the tool drive shaft and transferrable by axial displacement of the tool drive shaft from a position of rest in the direction of the drive into a working position, the clutch comprising a clutch element driven by the drive, a clutch element connected to the tool drive shaft and an intermediate clutch element arranged between these clutch elements, with the intermediate clutch element forming with a first one of the clutch elements an entrainment clutch and with the second clutch element a release clutch, such that in addition to a switch-off means for the screw-in depth, the screwing tool machine comprises a switch-off means for the screw-in torque, it is proposed that the switch-off means for the screw-in depth be adapted to be switched over in

Abstract: A hand-held impact tool operated by a pressure medium includes a work cylinder, a piston movable in the work cylinder by the pressure medium, and an impact member. A pressure medium container, preferably a CO.sub.2 -cartridge, is immediately attached to the housing of the tool so that no pressure medium conduit system or electric cable system are required. The force of the spring for driving the impact member is adjustable. The tool is provided with a displaceable hand grip and a releasing handle for releasing the impact member.

Abstract: A "hole bottom" hammer drill comprising a tubular body (1) supplied with compressed air, a drill bit (3) and a percussion piston (38) caused to move in an inner cylinder (7) by a mechanism distributing compressed air alternately below and above the piston.The hammer drill includes a device (29) for injecting gas oil into the chamber (71) above the piston (38) and a mechanism (34, 35) for triggering the injection during the upward stroke of the piston (38); the additional compression effects the combustion of the air-gas oil mixture, thus projecting the piston (38) towards the drill bit (3).

Abstract: Hydraulic fluid pressure moves a piston (22) against a body of incompressible fluid (14), compressing a spring (42). The pressure is released, and the force of the stored energy in the spring (42) is transmitted to the piston (22) by the body of fluid (14) and drives the piston (22) through its power stroke. The fluid (14) is vented to an outlet (8) before the piston (22) reaches the end of its power stroke, removing the force from the piston (22) and allowing it to free travel through the remainder of the stroke. When the motor (2) is operating and the load is removed from the piston (22), the hydraulic fluid inlet (10) is short-circuited to the outlet (8) and the motor (2) automatically shuts off.