Abstract: An electrical power tool includes a housing, an electrical motor, an end-bit holding section, a transmitting mechanism, a cap, and a lighting section. The housing has one end. The electrical motor is accommodated in the housing and is configured to generate a rotational driving force. The end-bit holding section is provided at the one end and is rotatable about a rotational axis. The transmitting mechanism transmits the rotational driving force to the end-bit holding section. The cap is attached to the one end. The lighting section allows an entirety of the cap to be luminous.

Abstract: An electrical tool, in particular drill and chiselling hammer, including a drive shaft and two driven members. The drive shaft is operatively connectable with the driven members by a respective one of a pair of coupling sleeves. The coupling sleeves are actuatable by a rotatable and mechanical actuating element, in particular a mechanical rotary switch. The actuating element of the electrical tool includes a transmission means or a transmission portion that is stationary with respect to the actuating element and which is contactable directly with the respective coupling sleeve for actuating the coupling sleeves.

Abstract: An impact drill that includes a drive motor located in a motor housing, an impact mechanism, and a tool fitting. The tool fitting and the impact mechanism are components of a swivel device that is located such that the swivel device may swivel relative to the motor housing.

Abstract: It is an object of the invention to provide an improvement in ease of operation of a driving mode switching mechanism in a hammer drill. According to the invention, a representative hammer drill includes a driving mode switching mechanism which has an operating part, a first switching member and a second switching member. The operating part can be turned to at least three rotating positions in its circumferential direction, while the operating part can be turned 360° on the rotation axis in the both directions. Thus, the user can select the desired driving mode in the shortest turning distance without passing though an unnecessary driving mode position. Therefore, ease of operation in mode change can be enhanced.

Abstract: The invention relates to a hand tool (1), particularly electric hand tool, having a drive (5), a tool shaft (3), a first overload clutch (14) and a transmission (6), which comprises a first and at least one second gear wheel unit (7, 8), said gear wheel units being operable alternatively to transmit torque. According to the invention, at least one second overload clutch (18) is provided and is permanently and exclusively operatively connected to the first gear wheel unit (7).

Abstract: A hand-held drill hammer has a housing, a shaft (12) connected to a drive shaft (30), and a lifting bearing (14). The lifting bearing (14) is supported and the shaft (12) for converting rotary motion into a reciprocating motion. In a first switching configuration, a percussion drive connection exists between the shaft (12) and the lifting bearing (14). In a second switching configuration, the percussion drive connection is interrupted. The lifting bearing (14) may be fixed with respect to a reference system of the housing in the second switching configuration.

Abstract: The invention is an electric hand tool embodied as a hammer drill and/or slide hammer, with a work spindle, a striking tool, and an electric drive motor which can be connected to an intermediate shaft driving the work spindle and/or to a striking tool drive, via a transmission and coupling device. The transmission and coupling device have a transmission, and the transmission is-a multi-stage spur gear mechanism, the gears of which are shifted by axial displacement of the intermediate shaft.

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: A clutch device for an electric machine tool that is drivable in a fashion selected from the group consisting of a rotary fashion, a percussion fashion, and both with an impact mechanism deliberately disengageable from or engageable with a spindle that drives a plug-in tool, has an intermediate shaft arranged between the spindle and an armature shaft of a drive motor and configured for transmitting drive energy, the intermediate shaft being axially movable so that the electric machine tool is switchable between operating modes through an axial movement of the intermediate shaft.

Abstract: This invention relates to a power tool one having a driven member 5 for releasably gripping a working element 4. The power tool is operable in a working mode in which the working element performs work, or an adjustment mode in which the driven member 5 grips or releases the working element 4. The power tool includes a powered selector means including a controller 6 which enables the operator to select the mode of operation of the power tool.

Abstract: A clutch arrangement for use in a power tool having a multi-speed transmission assembly. The clutch arrangement includes a clutch member and a follower member. The clutch member is coupled to a member of the transmission assembly that is proximate the torsional input of the transmission assembly and which must be in a non-rotating position to permit the transmission assembly to perform a torque multiplication operation. The follower member is biased into engagement with the clutch member to inhibit relative rotation therebetween. As the clutch member and the transmission member are coupled to one another, the transmission assembly is able to perform a torque multiplication operation. When, however, the torsion that is exerted onto the clutch member is sufficient to overcome the frictional engagement between the follower and clutch members, the clutch member, and the transmission member, rotate, thereby inhibiting the capability of the transmission to continue to perform the torque multiplication operation.

Abstract: A power tool with a housing, an electric motor having an output shaft that provides a first output torque, a first gear reduction element driven by the output shaft to provide a second output torque, a second gear reduction element, which can be operated in active and inactive modes, driven by the first gear reduction element to receive the second output torque and to provide a third output torque, a third gear reduction element, which is operable in active and inactive modes, driven by the first gear reduction element to receive the second output torque and to provide a fourth output torque, an output spindle operably driven by the second gear reduction element or the third gear reduction element, and a shift actuator. The shift actuator is employed to position the second and third gear reduction elements to achieve at least three overall speed ratios.

Abstract: A power tool (10) is described which has several modes of operation, such as drilling and screw driving modes. A clutch is provided with various settings for adjusting the torque at which the clutch interrupts power to a spindle (18). Furthermore, a two speed gearbox (16) is provided for adjusting the speed of the spindle. All of these variables are controllable from a single adjustment member or collar (26) thereby reducing necessary decisions needed to be made by an operator for a particular job in hand. For instance, when an operator wants the tool to operate in a screw driving mode, the gearbox is automatically set to drive the spindle at a low speed with the clutch being operable to interrupt drive when a torque force applied to the spindle exceeds a threshold value. Furthermore, if the tool is required to operate in a drilling mode, the gearbox is automatically switched to drive the spindle at a higher speed and the clutch is automatically rendered inoperable.

Abstract: A drilling machine is provided for breaking chips formed by drilling action into manageable lengths. The drilling machine comprises a first gear having a first axis of rotation, and a cam follower surface. It has a second gear having a second axis of rotation coincident with the first axis of rotation. A housing is provided configured to support the first gear and the second gear, the housing having a cam surface, a spring and a tool holder spindle having a third axis of rotation. The first and second gears are configured to impart both a linear feed and a rotation to the spindle. The first and second axes of rotation are coincident with the third axis of rotation such that the cam surface is urged into contact with the cam follower surface by the spring. The cam surface and the follower surface are shaped such that when the first gear rotates, the first gear is caused repeatedly to retract and then to advance, breaking chips that are formed.

Abstract: A hand-held power tool, in particular a rotary hammer, is indicated that includes a machine housing (10) with a tool fitting (12) integrated therein, the tool fitting (12) being rotatably drivable in a first mode and being non-rotatably fixable on the machine housing (10) in a second mode, and that includes a duty-type switch (20) with a coupling element (21) capable of being displaced to activate the modes, and an actuating element (22) that induces its displacement. To prevent maloperation and resultant damage to the machine when the operator switches between modes, the actuating element is designed as an electrical actuator (23), preferably as an electromagnet (25) controlled by an electronic control unit (24) (FIG. 1).

Abstract: A power tool with a housing, a motor, an output spindle and a transmission assembly with a transmission and a speed selector. The transmission includes a plurality of planetary transmission stages that couple the motor to the output spindle. The speed selector includes only one switch member that is slidably movable between three positions to cause the transmission to operate in a corresponding number of speed ratios.

Abstract: A portable power tool having a relatively compact multi-stage, three-speed transmission and a related method for operating a power tool with a multi-stage, three-speed transmission.

Abstract: In a power driver, a power take off (PTO) arrangement (to open/close a chuck) includes: a chuck actuating shaft and a coaxial PTO actuator shaft axially displaceable along, yet rotationally locked together about, a first axis of the power driver; an input shaft, supporting jaws of the chuck, and concentric to at least a portion of the chuck actuating shaft and a portion of the PTO actuator shaft; relative rotation between the chuck actuating shaft and the input shaft selectively being prevented and being caused by first and second configurations of the chuck actuating shaft and the PTO actuator shaft, respectively; and a PTO-control member, displaceable between first and second positions along a second axis parallel to the first axis, and coupled to adjust at least one of the chuck actuating shaft and the PTO actuator to achieve the first and second configurations, respectively.

Abstract: A method for operating a portable power tool having a multi-stage, three-speed transmission.

Abstract: A composite drilling tool comprises: a handle; and a driving portion installed at one end of the handle; the driving portion including a pneumatic portion, an electromotive portion, a coil and a battery; the pneumatic portion and the electromotive portion serving to drive the drilling rod through air power or electric power; the power of the electromotive portion being from the battery; the coil enclosing the drilling rod; when the drilling rod rotates, the magnetic flux from the magnetic unit will change so as to induce current in the coil and thus the battery is charged; and a drilling rod installed in the driving portion with a part being embedding into the driving portion and a part being protruded out of the driving portion for assembling a drilling head of various forms; and the drilling rod being installed with a magnetic unit.

Abstract: A pneumatic drilling machine is provided, comprising a pneumatic motor, a circuit for connecting the motor to a source of compressed air, a tool holder spindle, and a drive mechanism. The drive mechanism comprises a coupling shaft which can be moved to select a first mode of driving the spindle and a second method of driving the spindle. The mechanism has a driving cycle which comprises a stationary mode at the beginning and end of the cycle, and at least one phase for driving the spindle according to the first driving method, then a phase for driving the spindle according to the second driving method, then the stopping of the supply of air to the motor. A supply valve of the circuit is controlled pneumatically by the drive mechanism to interrupt the supply of compressed air to the motor at the end of the driving cycle.

Abstract: A portable power tool with a housing, a motor having a motor output member, a driven member and a transmission. The transmission, which is located in the housing, is configured to receive a rotary input from the motor output member and to produce a rotary output that is transmitted to the output spindle. The transmission has a plurality of planetary transmission stages, each of which including a ring gear, a planet carrier and a plurality of planet gears that are supported by the planet carrier for meshing engagement with the ring gear. The transmission further includes at least one member that may be configured in a first condition, which renders at least one of the planetary transmission stages operable in an active mode, and a second condition, which renders at least one of the planetary transmission stages operable in an inactive mode. The transmission is operable in at least three overall speed reduction ratios.

Abstract: A multi-speed transmission assembly for a rotary power tool. The transmission assembly includes a plurality of transmission stages, with at least two of the transmission stages employing a movable reduction element that permits the transmission stage to be operated in an active mode and an inactive mode. The movable reduction elements are coupled to a switching mechanism that switches the reduction elements in a predetermined manner to provide at least three-gear reduction or speed ratios.

Abstract: A flow guide configured for insertion in a cavity defined between an outer housing and a nested inner motor housing of a fluid driven tool. The flow guide defines a longitudinal axis and includes at least two longitudinal portions disposed parallel to the longitudinal axis and defining a longitudinal channel therebetween, and a rib being substantially circumferential and connecting the longitudinal portions at points defining a plane substantially transverse to the longitudinal axis. The rib defines a recess that permits fluid communication in the longitudinal channel across the rib.

Abstract: A portable power tool with a housing, a motor having a motor output member, a driven member and a transmission. The transmission, which is located in the housing, is configured to receive a rotary input from the motor output member and to produce a rotary output that is transmitted to the output spindle. The transmission has a plurality of planetary transmission stages, each of which including a ring gear, a planet carrier and a plurality of planet gears that are supported by the planet carrier for meshing engagement with the ring gear. The transmission further includes at least one member that may be configured in a first condition, which renders at least one of the planetary transmission stages operable in an active mode, and a second condition, which renders at least one of the planetary transmission stages operable in an inactive mode. The transmission is operable in at least three overall speed reduction ratios.

Abstract: A pneumatic drilling machine is provided, comprising a pneumatic motor, a circuit for connecting the motor to a source of compressed air, a tool holder spindle, and a drive mechanism. The drive mechanism comprises a coupling shaft which can be moved to select a first mode of driving the spindle and a second method of driving the spindle. The mechanism has a driving cycle which comprises a stationary mode at the beginning and end of the cycle, and at least one phase for driving the spindle according to the first driving method, then a phase for driving the spindle according to the second driving method, then the stopping of the supply of air to the motor. A supply valve of the circuit is controlled pneumatically by the drive mechanism to interrupt the supply of compressed air to the motor at the end of the driving cycle.

Abstract: A multi-speed transmission assembly for a rotary power tool. The transmission assembly includes a plurality of transmission stages, with at least two of the transmission stages employing a movable reduction element that permits the transmission stage to be operated in an active mode and an inactive mode. The movable reduction elements are coupled to a switching mechanism that switches the reduction elements in a predetermined manner to provide at least three-gear reduction or speed ratios.

Abstract: A device for switching operating modes for an at least partially rotational and percussive hand tool machine having an overload clutch, which is arranged between a hollow driving guide cylinder (3) containing an axially striking impact piston (2) and a rotating, driving crown gear (4) on the guide cylinder (3) and which can be switched into different operating modes using an externally manually switchable, axially displaceable switching member, wherein at least one operating mode is rotationally driven, wherein the axially displaceable switching member engages rotationally form-lockingly into a freely rotational coupling ring (6) of the overload clutch mounted relative to the guide cylinder (3).

Abstract: The object of the invention is a device, intended for a multifunctional, hand-held tool machine, for example, an electric combination hammer, for the ON/OFF switching or changeover of individual system functions when changing the processing mode, for example, from “hammer drilling” to “chiseling”. Pursuant to the invention, the changeover device, which is to be actuated by the user, is coupled with a mechanical driving mechanism, by which a bistable switch, comprising two mutually oppositely movable elements, is actuated. In a combination hammer, the invention guarantees that, when the chiseling operation is selected, certain functions of the system, such as a monitoring of the reaction moment, are interrupted or changed over.

Abstract: A power tool includes a housing rotatably secured to a seat and having an internal gear and having a bore for rotatably receiving a driving shaft. A motor is secured to the seat and includes a spindle having a pinion engaged with the internal gear for driving the housing to rotate relative to the seat. A pawl is rotatably secured in the housing, and has two ends selectively engaged with the shaft to rotate the shaft in either direction when the housing is rotated relative to the seat by the motor with a speed greater enough to cause the pawl to engage with the shaft.

Abstract: A hand held power tool has a housing, a drive, a mechanical striking mechanism with a striker, a drive element for driving the striker in its striking movement and having at least one curved track with raised and depressed portions, and a sensing element in operative connection with the striker supported on the drive and having a sensing member bringable in operative position with the raised and depressed portions of the curved track.

Abstract: The present invention discloses a portable electric rotary power tool having a plurality of gear reduction elements connected to a motor to receive a first output torque and drive an output spindle. At least two of the gear reduction elements have a common input member and a common output member. A shift actuator is in selective communication with the two gear reduction elements, so that in a first position, these elements are each in a locked mode for providing the first output torque to the spindle. In a second position, the first is in a reduction mode and the second is in a disengaged mode for providing a second output torque to the spindle. In the third position, the first of these elements is in the disengaged mode and the second is in the reduction mode for providing a third output torque to the spindle.

Abstract: A speed changing mechanism includes two planetary gear sets and a movable gear that is controlled to be movably engaged with one of the two planetary gear sets to generate two different speeds. A third speed can be output when the movable gear is moved to a position where the movable gear is not engaged with either of the two planetary gear sets.

Abstract: A hand tool with an adjustable rotational speed and torsion force includes a shaft rotatably received in a body of the hand tool and driven by a motor that is mounted in the body. A first planet gear set is longitudinally connected to one end of the shaft opposite to the motor and a second planet gear set is longitudinally connected to the first planet gear set. The shaft is longitudinally movable in the body. The hand tool only has the first planet gear set acted thereon when the shaft is pushed toward the second planet gear set. The first planet gear set and the second planet gear set are acted on the hand tool at the same time when the shaft is pulled.

Abstract: A pneumatic ratchet drive wrench of the present invention includes a pair of single springs that each bias a corresponding pawl into engagement with an output member and inhibit counter-rotation of the output member opposite the corresponding pawl. The pawl and spring construction allows the wrench head to be smaller than conventional pneumatic ratchet drive wrenches, providing better wrench access into small spaces. The spring is inexpensively formed as one piece of spring wire having independent spring coils for biasing the pawl and inhibiting counter-rotation of the output member.

Abstract: A hand power tool has a tool, a hammer tube, a striking mechanism having a striker and an anvil with an integrated receptacle for the tool which is strikingly drivable in the receptacle, and a blocking element which connects the tool and the anvil in an axial direction.

Abstract: A hand-operated machine tool is disclosed that rotationally drills or percussively chips or both. An embodiment of the hand-operated machine tool includes a toolholder that is used to hold tools having a grooved shank. The toolholder has a toolholder body and at least one radially moving locking member, for example a locking sphere, that is insertable into a groove in the tool and the locking member is radially locked in position by a retaining element that may be displaced by an actuating element to a position that radially releases the locking member. In an embodiment of the invention, the toolholder has at least one sealing device that seals at least one chamber outwardly surrounding the locking member. The sealing device includes at least one sleeve-shaped component that is separate from the actuating element and at least partially defines the volume referred to as the chamber.

Abstract: A hammer drill has a motor which drives an axially displaceable intermediate gear mounted in an intermediate gear arrangement. An impact mechanism is formed by including interacting impact cams between either the intermediate gear and the housing, or the motor armature shaft and the housing to generate a reciprocating motion on an output spindle or shaft. A spindle locking mechanism is included which causes an intermediate gear to be disengageable with respect to the output shaft, while still permitting the impact mechanism to be engaged. Such an arrangement allows the hammer drill to operate in a hammer-only or chipping mode.

Abstract: An impact rotary tool includes an output shaft having an anvil at an end portion thereof, a hammer having a projecting portion applying an impact force to the anvil under a predetermined condition, a driving shaft connected to the hammer through a cam mechanism, and a changeover mechanism for changing the connection between the driving shaft and the output shaft. The mechanism is arranged along with a common axis defined by the driving shaft and the output shaft. The changeover mechanism includes a connecting member accommodated into the driving shaft in a first condition, and connecting the driving shaft and the output shaft in a second condition.

Abstract: A multi-speed transmission assembly for a rotary power tool. The transmission assembly includes a plurality of transmission stages, with at least two of the transmission stages employing a movable reduction element that permits the transmission stage to be operated in an active mode and an inactive mode. The movable reduction elements are coupled to a switching mechanism that switches the reduction elements in a predetermined manner to provide at least three-gear reduction or speed ratios.

Abstract: A surgical instrument having a locking mechanism for preventing an output shaft of the surgical instrument from rotating and a further locking mechanism for mounting a battery pack to a distal end of a housing of the surgical instrument. The surgical instrument further includes a clutch mechanism for limiting the torque of a drive shaft of the surgical instrument. The locking mechanism for preventing the output shaft from rotating includes a locking switch which mates with a locking cap disposed on the output shaft. The locking mechanism for mounting the battery pack to the housing includes a groove at the distal end of the housing and a retaining ring which engages the groove when the battery pack is mounted on the housing. The clutch mechanism includes a clutch plate that interfaces with both the output shaft and the drive shaft and prevents failure of the motor shaft.

Abstract: The invention is a pneumatic tool with a reverse valve having an overdrive. In particular, the pneumatic tool includes a housing, a rotor, rotatably mounted within the housing, an output shaft operatively coupled to the rotor, and pressure chambers defined between the housing and the rotor. A pneumatic reverse valve having an overdrive is operatively coupled to the rotor. The overdrive provides increased torque and increased speed to the output shaft. The reverse valve controls flow of pressurized air to a multi-chambered motor of the tool such that the direction of the motor can be reversed and the number of pressure chambers receiving pressurized air can be selected regardless of direction.

Abstract: A surgical instrument having a locking mechanism for preventing an output shaft of the surgical instrument from rotating and a further locking mechanism for mounting a battery pack to a distal end of a housing of the surgical instrument. The surgical instrument further includes a clutch mechanism for limiting the torque of a drive shaft of the surgical instrument. The locking mechanism for preventing the output shaft from rotating includes a locking switch which mates with a locking cap disposed on the output shaft. The locking mechanism for mounting the battery pack to the housing includes a groove at the distal end of the housing and a retaining ring which engages the groove when the battery pack is mounted on the housing. The clutch mechanism includes a clutch plate that interfaces with both the output shaft and the drive shaft and prevents failure of the motor shaft.

Abstract: A kind of knob switch device relates to a clutch control device setting inside the decreasing box, and relates to a switch device setting outside the decreasing box. The clutch control device comprises the switch block, the switch set, the vibration block and the vibration set on the output shaft serially. The switch device comprises a stop ring, a stop board and a gyrator ring. With rotating the knob, we can drive the stop ring and the gyrator ring to rotate at the same time. Then it makes the screw orbit of the stop ring to push the jut of the stop board. When the clutch transits the device and makes the turning ring to rotate for a fixed angle, and it makes the knob, the inner gear and the turning ring to rotate at the same time. Then the switch block fits the switch teeth and makes the teeth of the vibration block to fit the teeth of the vibration set and make the output draft to have action of vibration at rotating time.

Abstract: A pneumatic rotary tool capable of operating in forward and reverse directions includes a housing and an output shaft projecting from the housing for transmitting torque to an object. An air motor drives rotation of the output shaft in the forward and reverse directions. Air passages extend from an air inlet to the motor for delivering pressurized air to the motor. One passage delivers air to the motor to power the motor to drive the output shaft in the forward direction and the other passage delivers air to the motor to power the motor to drive the output shaft in the reverse direction. A selector valve is disposed between the air inlet and the air passages such that fluid communication between the air inlet and the air passages is blocked except through the selector valve.

Abstract: A reversible power wrench includes a housing (10), a rotation motor, and a power transmission coupling the motor to an output shaft (21), and further includes a reduction gearing (20) with first planetary gearing (28) for transferring torque in the "forward" direction of rotation and a second planetary gearing (29) for transferring torque in the "reverse" direction of rotation. The first and second planetary gearings (28, 29) have rotationally interconnected sun gears (31, 39) and a common planet wheel carrier (34).

Abstract: A hand-held machine tool for a workpiece, comprising a casing having first and second hollows therein, an electric motor enclosed in said first hollow and having a driving shaft, a driving mechanism accommodated in said second hollow and being drivingly connected to said driving shaft. The driving mechanism includes a driven shaft and means for rotating and oscillating the driven shaft. A tool holder is provided on the driven shaft for holding a tool having a working surface adapted for sanding, rasping or filing a workpiece, a handle is fixedly connected to the casing and includes electric power conducting means and a switch for energizing and deenergizing the electric motor, and a guide and support for mounting attached to the casing.

Abstract: A power tool (20) includes a modular drive system in which the motor (22) and transmission (24) consist of separate self-contained modular units which can be assembled together by simply sliding and rotating the motor housing (42) and the transmission housing (70) relative to each other. The motor (22) has a D-shaped rotary drive shaft (44) which is inserted into a D-shaped aperture (86) in the drive gear (84) of a planetary gear system (80) contained within the transmission housing (70). Guide pins (92) extending from the transmission housing (70) are inserted into guide holes (94) in the motor housing (42) when the D-shaped drive shaft (44) is inserted into the D-shaped aperture (86) in the drive gear (84) to align the housings (42,70) with each other. A bushing (46) at the front of the motor housing (42) is inserted into a central opening (76) at the rear of the transmission housing (70) to couple the housings (42,70) together.

Abstract: A dual-function electrical hand drill includes an electrical motor to which a driving shaft is coupled via a speed reduction gear train. A chuck is releasably secured to the driving shaft to be rotatable therewith. A setting ring is provided to change the rotation speed and thus the output torque by applying force to the speed reduction gear train via the compression of a helical spring. A serrated member, secured to the driving shaft, is provided to be movable between a disabled position and an enabled position in which enabled position, the serrated member engages a counterpart serration and is biased by a spring to allow the chuck and the bit secured thereto to move to and fro by the sliding between the serrations when the bit is reacted by a work piece. The movement of the serrated member between the enabled position and the disabled position is controlled by the setting ring so that the selection of both the output torques and the operation modes can be accomplished by a single setting member.

Abstract: This invention relates to a drive unit comprising a frame; a rotating shaft, a first fluid motor presenting a cam fixed with respect to the frame; and a cylinder block fast with the shaft driven by the first motor at a first speed of rotation.According to the invention, the shaft presents a recess conveying a drilling fluid; the cylinder block of the first motor is coaxial to the axis of rotation; drive unit comprises a second motor coupled in rotation to the shaft and driving it at a second speed of rotation higher than the first speed of rotation; a first pinion gear is fast with and coaxial to the shaft; the second motor presents an output shaft fast with a second pinion gear meshing with the first pinion gear; and the first motor is of the type with "disengageable pistons".One application is the production of a high-performance drilling assembly.