Abstract: A magnetorheological (MR) actuator device comprising two or more MR actuator units. Each of the MR actuator units may include a motor, an MR fluid clutch apparatus operatively coupled to the motor to receive torque from the motor, the MR fluid clutch apparatus operable to generate a variable amount of torque transmission when subjected to a magnetic field. An output member is provided, a transmission operatively coupling the at least two MR actuator units to the output member, for the output member to receive torque from the MR actuator units. A controller for controlling the two or more MR actuator units to drive the output member, the controller driving the output member in at least an antagonistic mode in which the MR actuator units transmit torque in opposite directions to the output member. A collaborative mode may be provided to combined the torque of the two or more MR actuator units in a common direction on the output member.

Abstract: The present invention is directed to systems and methods for redundant flight control configured for use in an aircraft. More specifically, a system is provided that includes a plurality of actuators that are configured to move a flight component of an aircraft such that one actuator is configured to move the flight component if the other actuator fails to move the flight component upon receipt of an attitude command from a pilot control.

Abstract: A speed change device for shifting the gear of a transmission. The transmission includes a first shifter shaft, a first shifter element associated to the first shifter shaft and arranged for movement in an axial direction of the first shifter shaft for actuating a first set of gears. It further comprises a second shifter shaft and a second shifter element associated to the second shifter shaft and arranged for movement in an axial direction of the second shifter shaft for actuating a second set of gears. One of said first and second shifter shafts is hollow and the other of said first and second shifter shafts is partly arranged coaxially inside the hollow shaft.

Abstract: A ball screw drive (10) including a threaded spindle (12) and a spindle nut (14) which at least partially coaxially encloses the threaded spindle (12) and has a stop at an axial end face (18). A multiplicity of balls can circulate in the space (16) between the threaded spindle (12) and the spindle nut (14). A radial stop element (22) is connected to the threaded spindle (12) in a force-fitting manner and adapted to interact with the complementary axial end face (18) of the spindle nut (14). A bearing element is provided for receiving a first longitudinal end of the spindle nut (12). The radial stop element (22) and the bearing element are designed in combination as an integral bearing/stop element (24) which has two anti-rotation features (26, 28).

Abstract: The disclosure is a linear actuator. A transmission mechanism includes a motor, a gear set and a screw rod. A releasing mechanism is disposed between the gear set and the screw rod and includes a driving gear, a first clutch, a second clutch and a sliding sleeve. A toggle restraining mechanism includes a stem, a rotating element and a restraining assembly. The rotating element has a restraining hole and a rotating arm. The restraining assembly includes a restraining presser, a restraining spring and an engaging element. The stem is moved to rotate the rotating element, the rotating arm is rotated with the rotating element to push the sliding sleeve. The sliding sleeve is pushed by the rotating arm to separate from the second clutch. The engaging element is engaged in the restraining hole to restrain the rotating element from rotating when the rotating element is rotated to a specific angle.

Abstract: The present disclosure relates to the field of stroke-controlling mechanism, and discloses a stroke-limiting control assembly and an operating method. The stroke-limiting control assembly comprises a housing and a film winding. A transmission input gear, a transmission gear, a guide wheel, and a spring box that can be rotated to reset by an elastic force are rotatably connected within the housing. When a moving component moves to an end of an upper stroke, a first metal needle abuts a first proximity switch. When the movable component moves to an end of a lower stroke, a second metal needle abuts against a second proximity switch. At least a stroke-limiting control assembly is provided which enables simplification of a product requiring stroke-limiting, such as an electric jack or an electric support leg, by arranging the proximity switches outside a screw nut lifting unit in the electric jack or the electric support leg.

Abstract: An actuator for level adjustment of a motor vehicle utilizes a ball screw and a locking unit provided for blocking the ball screw. The actuator has a spindle drive which can be actuated by an electric motor via a gear. The spindle may be fastened to a damper of the chassis of a motor vehicle, to a wheel carrier or to the body or a subframe of a motor vehicle. With the aid of a locking unit of the spindle drive, the rotation of the spindle nut can be optionally blocked or enabled. The locking unit includes a locking element which engages a locking contour attached to the end face of a rotatable element of the gear.

Abstract: A diagnostic service system includes one or plurality of factory monitoring systems configured to perform monitoring of at least one machine; a service center management device that is connected with the one or plurality of factory monitoring systems via a network; one or plurality of service centers that are connected with the service center management device; and a plurality of service terminals connected with one service center or each of the plurality of service centers via a service control. The plurality of service terminals are used by each responder capable of fault diagnosis of the machine, and when fault of a machine occurs, one of the plurality of service terminals is selected via the service center management device and the one service center or plurality of service centers.

Abstract: A system and method for controlling a field device includes a valve coupler having a first portion configured to couple to an actuator rod of an actuator, a second portion configured to couple to a movable component of a control valve, and one or more sensors measuring one or more parameters indicative of the health and/or remaining service life of the control valve assembly and/or one or more components of the valve assembly. Further, at least one of the one or more sensor devices may generate energy from the control valve assembly and/or the operating environment of the control valve assembly for operation of the electronics.

Abstract: A spindle drive includes a housing, a spindle, e.g., a threaded spindle, a trapezoidal threaded spindle, a ball circulation spindle or planetary roller spindle, and a spindle nut that is operatively connected to the spindle. The spindle nut is guided on the housing in a manner that allows it to be moved back and forth in response to rotational movement of the spindle in the axial direction thereof. On at least one axial side, the spindle nut includes an annular groove or is connected, e.g., screw-connected, to a part that has an annular groove. An annular collar is formed on the housing. The collar enters or extends into the annular groove in response to the spindle nut reaching an associated or a corresponding axial position.

Abstract: The invention relates to a movable barrier operator with a removable power supply module for supplying power to the operator from a remote location. The power supply module may be decoupled from a barrier operator frame or housing, and installed in a remote location; the operator may therefore be observed and diagnosed remotely via a user interface that includes status indicators. In an exemplary embodiment, the user interface comprises one or more LED indicators to provide a user with information pertaining to the power supply of the operator.

Abstract: A rotary drive device includes a housing element, a drive shaft and a driven shaft, both rotatably mounted in the housing element, a transmission device that transmits torque from the drive shaft to the driven shaft, and a braking device configured to counteract rotation of the drive shaft. The braking device includes a drive shaft input element, a braking element connected to the housing element for conjoint rotation, and a coupling element adjustable with respect to the input element. A braking force exerted by the braking device is greater when the coupling element is located in a first position than when located in a second position, and the coupling element assigned to the driven shaft so that adjustment from the first position to the second position is triggered by exceeding a threshold value of the difference in torque between the drive shaft and the driven shaft.

Abstract: A shut-off valve housing having a through-channel extending inside a main body between an inlet opening and an outlet opening, and a valve seat disposed inside the through-channel. To reduce flow losses, an outflow region of the through-channel immediately downstream of the valve seat on an outflow side has an inwardly curved contour.

Abstract: A linear actuator includes an electric motor, which through a transmission drives a spindle unit having a spindle with a spindle nut. A tubular adjustment element is displaced either outwards or inwards depending on the direction of rotation of the spindle unit. A brake in the shape of a coil spring and a cylindrical element are arranged for retaining the tubular adjustment element in a given position when the power for the electric motor is cut off. The cylindrical element is configured as a separate cylindrical element arranged on the spindle or a shaft in the transmission. The separate cylindrical element is preferably arranged on a rear end of the spindle between the rear mounting and the bearing for the spindle. In contrast to known constructions, the heat generation is limited, as the heat is led out to the rear mounting.

Abstract: This DC brushless motor (1) is provided with a stator (2) that has exciting coils (31, 32) and a rotor (4) that is positioned coaxially to the stator (2). The stator (2) has a quasi-E-shaped cross-section in the axial direction at the radius part; a plurality of protrusions (212, 222, 232) serving as magnetic poles are formed on the respective 3 parallel sections (211, 221, 231) of the E in the same number in the circumferential direction; and of the magnetic poles (212, 222, 232) formed at the 3 parallel sections (211, 221, 231) of the E, the top and the bottom magnetic poles (212, 232) are respectively positioned so as to be shifted in the opposite directions in the circumferential direction with respect to the center line of the middle magnetic pole (222). Changes in the magnetic resistance between the stator (2) and the rotor (4), which are caused by the flow of a magnetic flux generated around the exciting coils (31, 32), are utilized as a driving force.

Abstract: A linear actuator system is provided. The linear actuator system comprises a motor with an output shaft. The output shaft comprises splined features. The linear actuator system also comprises a lead nut with a threaded inner surface. The attachment mechanism has an inner surface configured to functionally engage the splined features. The attachment mechanism also has an outer surface comprising a first and second textured surface. The first textured surface is different from the second textured surface. The lead nut is configured to engage with one of the first and second textured surfaces.

Abstract: An actuator is suitable for providing linear motion between two points, and may be used, for example, in motorized positioning of an automobile steering column. The actuator includes a threaded spindle connected to a drive motor via a gear set, a first connection interface mounted on the spindle and engaged with the spindle thread, and a second connection interface mounted on the spindle and engaged with the spindle thread. The second connection interface is moveable along the spindle axis relative to the first connection interface when the spindle is driven by the drive motor. The actuator is arranged such that the first and second connection interfaces are disposed on the same side of the gear set.

Abstract: A linear actuator includes a planetary gear system including a sun gear, a ring gear, and a planet carrier. A linear output mechanism is coupled to the planetary gear system. A first motor is configured to drive a first input shaft, and the first input shaft is coupled to the planet carrier. A second motor is configured to drive a second input shaft, and the second input shaft is coupled to one of the sun gear and the ring gear.

Abstract: An applicator for applying a liquid medium, in particular a liquid decorative medium in the cosmetic field, includes at least one first section having an applicator head, at least one second section adapted to receive at least one reservoir container for the liquid medium. The reservoir container includes at least one piston and at least one third section having at least one advancing mechanism for emptying the reservoir container by moving the piston. The at least one advancing mechanism can be driven by at least one electrical gear motor. The at least one electrical gear motor is arranged together with the advancing mechanism in the at least one third section of the applicator.

Abstract: An actuator includes two abutment elements and an adjusting device for changing their spacing in a translational displacement direction. A support element is provided between the abutment elements, a drive motor is supported by the support element, a first spindle nut is rotatably supported by the support element, a second spindle nut is rotatably supported by the support element, a first spindle engages the first spindle nut and is connected to one abutment element, and a second spindle engages the second spindle nut and is connected to the other abutment element. Two limit switches are mounted on a switch support on the support element and spaced apart from each other in the translational displacement direction. A first limit switch actuating element is attached to one of the abutment elements, and a second limit switch actuating element is attached to one of the spindles.

Abstract: A lead screw attachment mechanism for a linear actuator system is provided. The attachment mechanism comprises an attachment housing comprising a fixed cover configured to house the attachment mechanism. The attachment mechanism comprises a first coupling mechanism configured to couple the attachment mechanism to an output shaft of a motor and a second coupling mechanism configured to couple the attachment mechanism to a lead nut, wherein the lead nut is configured to move linearly along an axis defined by a length of the attachment mechanism. The attachment mechanism is configured to rotate about the axis, within the fixed cover.

Abstract: A stop module halts rotation of a shaft of a rotational drive system when an axial stroke limit is reached without the use of frictional brake plates. The module has a fixed nut and a pawl carrier coaxially mounted on the shaft for axial travel along the shaft and rotation with the shaft. The pawl carrier includes a screw portion mated with the nut such that rotation of the pawl carrier with the shaft causes the pawl carrier to travel axially along the shaft. A pawl member is pivotally coupled to the pawl carrier, and a stop element is fixed at an axial limit location. The pawl carrier is axially displaceable from a non-limit position wherein the pawl member is clear of the stop element during rotation to a limit position wherein the pawl member is interfered with by the stop element during rotation to stop rotation of the shaft.

Abstract: Electronically controlled linear pump drive actuator for a dispensing pump has a servo motor unit having a stator with front and rear faces and a central hollow cavity, a rotor coaxially in the hollow cavity with a front portion having a front end with an open central bore and a shaft with a stepped diameter forming a rear extension, front and rear support members respectively for the front and rear faces, a support bearing in the rear member, a front bearing, and a position sensor; a ball screw drive mechanism having a nut connected with the rotor and a screw shaft having a front end section; a hollow cylinder attached to the front member's front end; an actuator member axially moveable in the hollow cylinder with a central rear part fixed to the front end section, and a hollow front part; and a pump plunger adaptor.

Abstract: An exemplary device for use in an elevator system includes at least one friction member that is selectively moveable into a damping position in which the friction member is useful to damp movement of an elevator car associated with the device. A solenoid actuator has an armature that is situated for vertical movement. The armature moves upward when the solenoid is energized to move the friction member into the damping position. The armature mass urges the armature in a downward vertical direction causing the friction member to move out of the damping position when the solenoid is not energized.

Abstract: A threaded spindle (11), having a drive part (20), which has a longitudinal axis (A) and is mounted in a first journal (70), and having a threaded part (30), which has a longitudinal axis (B), and having a threaded nut (50), which is mounted in a second journal (80a; 80b) and in which the threaded part (30) is guided. The drive part (20) and the threaded part (30) are formed as separate parts and are each provided with at least one coupling element (25, 55), which are connected to each other in an articulated manner by plugging together. An offset of the longitudinal axes (A, B) can be compensated in this manner. The two-part threaded spindle (11) forms a threaded drive with the threaded nut (50) thereof, which can for example be used in a parking brake of a vehicle braking system.

Abstract: A method for producing a threaded nut (10, 26) of a screw drive, in particular of a ball screw (7, 24), which threaded nut (10, 26) has, on one axial end, a recess (45) which extends over a circumferential segment and which is open at the end side, wherein said recess (45) is delimited radially by a circumferential wall of the threaded nut (10, 26), and wherein said recess (45) is delimited axially by a base (54) formed on the threaded nut (10, 26), and wherein said recess (45) is delimited in the circumferential direction by a stop surface (47), which is formed on the threaded nut (10, 26), for a projection (44), produced according to the following steps: a blank is deformed in a deformation process by deformation of material so as to form the recess (45), wherein the base (54) and the stop surface (47) and the circumferential wall are integrally connected to one another.

Abstract: A linear electro-mechanical actuator comprises a housing with a reversible DC-motor (1), which through a transmission (2) can move an activation element (5) between two end positions. The activation element (5) will in the two end positions cause the electrical end stop switches (17, 25) to be activated for interrupting the current for the DC motor (1) in the end positions of the activation element (5) for running the motor (1) in one direction. Parallel to the end stop switches (17, 25), an extra set of switches (21, 23) are incorporated for determining in which end position the activation element (5) is located.

Abstract: A device has a torque-limiting unit of a power drill, wherein torque-limiting unit is intended to limit a screwdriving moment in a screwdriving function; and a power drill is provided with the new torque-limiting unit.

Abstract: A device for interrupting selectively a rotary translational movement, includes a threaded elongated element and an element having a female thread mating with the tread of the elongated element, one of said elements performing a translatory movements as far as at least a position defined by an end-of-travel stop as a result of engagement with the other element, and said translating element being able to undergo momentary deformation upon reaching said at least one end-of-travel position with the effect of being disengaged from the other element.

Abstract: A driver comprises a direction-switching means which switches a rotation direction of a rotary driving source based on a direction instruction signal, a current amplifier/limiter which converts a voltage outputted from the direction-switching means into a corresponding current and which limits the current to a preset reference current IMAX (threshold value), a current sensor which detects the current supplied to the rotary driving source, and a current loop which feeds back a detection signal supplied from the current sensor to an upstream side of the current amplifier/limiter.

Abstract: A reciprocal-movement power tool includes a movable blade reciprocally movably provided on a main body. A receiving plate that supports an angle iron to be cut is supported on the main body at a position in front of the movable blade. The movable blade is fixed on a front tip of a rod-shaped shuttle screw. The shuttle screw moves back and forth in the axial direction within a tubular screw shaft. The screw shaft is carved with a female screw portion and is rotated through a joint spindle that is deceleratingly rotated upon rotation of the motor through a deceleration means. The shuttle screw has a male screw portion that is threadingly engageable with the female screw portion.

Abstract: An improved linear actuator incorporates a DC motor whose stator is secured to a frame is provided for. To improve operational longevity and reliability of a linear actuator, the improved actuator includes a retention clutch and an axial load limiter. An axially configured retention clutch is configured to slidably fit within the open inner channel diameter of an axial load limiter and over a motor shaft of a linear actuator. In operation, the retention clutch reduces the impact loads on the stop and extending the fatigue life of these wearable components. Similarly, when the screw encounters axial loads during operation, these loads are distributed across both the axial load limiter and the motor, thereby reducing direct forces on the motor and contributing to an extended use of the motor component.

Abstract: A stop apparatus for a gear actuator includes a traveling stop nut that has adjustable positions and travels on a screw on an input shaft. The stop nut is mounted to threadably travel on the stop screw. A stop guide is attached to the stop screw and prevents rotation of the stop screw relative to the gear actuator and permits longitudinal travel of the stop screw during rotation of the input shaft. The stop nut abuts a stop surface upon a predermined amount of rotation of the input shaft to prevent further rotations.

Abstract: A system for raising and lowering a sectional overhead door between an open position and a closed position including, a counterbalance system adapted to be connected to the door, an operator motor assembly mounted proximate to the sectional overhead door in the closed position of the sectional overhead door, at least a portion of the operator motor assembly movable between a door operating position and a door locking position, and a locking assembly (370) having an engaged position to hold the motor assembly in the operating position and a disengaged position to release the motor assembly allowing it to move to the door locking position. The system may be provided with a remote light assembly having a switchable light source in sensing communication with the operator motor such that operation of the motor activates the light source.

Abstract: The invention concerns a piston wherein the mobile screw (2) is engaged in the bolt (8) integral with the mobile assembly (1). It is provided with a cylindrical axial housing (10) wherein is engaged the rod (7) integral at its front end with the expander assembly (4). At the end of its front travel, the rod is retained by its flange (19) pressed on the stop (11) such that the expanding ring (5) is compressed by the thrust of the piston body (3) and causes the flexible envelope (6) to expand.

Abstract: There is described an actuator comprising an outer tube and an inner tube. In the actuator there is provided a spindle co-operating with a bushing for creating the displacement of the actuator by means of a motor. In order to establish an end stop in a secure way for preventing a wedging of the spindle and the bushing in extreme positions for the actuator, the bushing is disposed rotatable in relation to both tubes as it is arranged rotatable in a bushing housing. The actuator is arranged so that friction between the bushing and the bushing housing is greater that the friction occurring between the spindle and the bushing. Hereby rotation of the spindle will displace the bushing along the spindle until it reaches an extreme position. By an extreme position a pin on the bushing will hit a pin mounted in the spindle.

Abstract: An electromotive adjustment assembly, includes at least two spindles disposed in parallel spaced-apart relationship, and a motor unit coupled in driving relationship with the spindles for operating the spindles.

Abstract: A screw actuator arrangement comprises a rotatable input shaft which is arranged to be driven, in use, by a drive arrangement. The input shaft is coupled to a non-rotatably mounted output shaft, and has a screw thread formation including a helical groove within which a plurality of spherical members are received to provide a ball screw coupling between the input and output shafts. The actuator further comprises means for applying a braking load to the input shaft so as to limit loading of the drive arrangement in the event that an external overload is applied to the output shaft, in use.

Abstract: A linear actuator for providing linear motion of an output shaft member and automatically disconnecting the shaft from a gear train comprising a rotatable shaft adapted to be coupled to an electrically powered gear train for causing rotation of the shaft; a shaft member mounted onto the rotatable shaft and axially moveable between a retracted position and an extended position in response to rotation of the shaft; a rotatable screw co-acting with the gear train to rotate in response to movement of the gear train; a second member mounted on the rotatable screw and axially moveable in response to rotation of the screw between the retracted position and the extended position; a switch unit located at at least one of the extended and retracted positions and responsive to engagement with the moveable second member for causing an electrical disconnection between the gear train and a power source to cause termination of shaft rotation; and a member coupled to the rotatable shaft for disconnecting the shaft from the g

Abstract: A screw actuator comprising first and second relatively rotatable members, a screw thread formation in the first member including a helical groove, spherical elements carried by the second member and in rolling engagement in the helical groove to form a ball screw coupling between the first and second members, the groove being of sufficient width to allow the spherical elements to move laterally within the groove, and a brake member carried by the second member and defining a screw thread formation which is received in the groove of the screw thread formation of the first member, the brake member being angularly moveable relative to the second member by rotation of the first member relative to the second member, between a first angular position in which the screw thread formation of the brake member is cooperable with that of the first member, and a second angular position in which the screw thread formation of the brake member is not cooperable with that of the first member.

Abstract: A linear actuator utilizing limit switches to implement reliable and effective travel limit functions. The actuator having a robust construction, lower part count, smaller dimension, and lower assembly cost.

Abstract: A ball screw and nut linear actuator has a motor and a ball nut and screw assembly in side by side disposition. Gearing connects with the motor shaft to drive the screw and a housing for the gearing and ball nut and screw assembly includes an elongate housing tube within which the screw assembly is housed. The nut incorporates an extension sleeve assembly for extending movement out of the housing tube which anchors the screw against axial movement while jounaling it for rotation. A pin and axial track connection between the extension sleeve assembly and the housing tube guides the extension sleeve assembly in axial movement and prevents relative rotation of the housing tube and sleeve assembly.

Abstract: In a device for fixing a ball screw/nut mechanism, including a ball screw and a ball nut, safe from turning. The ball screw/nut mechanism generates a linear movement to displace a first subassembly until it rests on a second subassembly. A blocking device is provided, which is adapted to fix the rotating part of the ball screw/nut mechanism, when both subassemblies are in contact, safe from turning through a reaction force originated by an external force and by overcoming the force of a first resetting means. When the parts are in contact, the blocking device is positioned in a determined distance from the first subassembly, and when the external force, generated by the drive device, arises the turnable part is safe from turning, until the determined distance between the first subassembly and the blocking device is compensated for.

Abstract: A linear actuator includes a motor having a rotatable output shaft, a lead screw having a worm gear thread, a forward end and a rear end, a worm gear drive train connected between the motor output shaft and the lead screw to convert the rotary motion of the motor output shaft into rotary motion of the lead screw, an extension tube assembly mounted at the forward end of the lead screw, where the extension tube assembly includes an extension tube concentrically disposed around the forward end of the lead screw, the extension tube having a forward end for contacting a device requiring linear motion, and a rear end, a nut connected to the rear end of the extension tube and threadedly mounted on the lead screw so that rotation of the lead screw moves the nut and the extension tube assembly axially along the lead screw, and a mounting adapter positioned at the rear end of the lead screw for rotatably mounting the lead screw and for attaching the linear actuator to a support structure.

Abstract: A simple, inexpensive and reliable screw type linear actuator includes a drive screw, a nut disposed thereon, and a reciprocating drive tube radially disposed over at least a portion of the drive screw. A first clutch member has a first clutch surface bearing upon a complimentary clutch surface which is operatively connected to the drive tube, whereby outboard movement of the nut upon rotation of the drive screw causes the first clutch surface on the first clutch member to bear upon the complimentary clutch surface and urge the drive tube in a direction toward the outboard end of the drive screw. A compression member urges the first clutch member axially away from the nut, and a retainer allows only limited axial movement of the nut with respect to the drive screw, whereby the nut and the first clutch member are always maintained in splined engagement.

Abstract: Method and system are provided for controllably driving a rotary drive of a rotary index table assembly utilizing a PLC which receives various sensor signals including a feedback signal from a resolver to generate a reference central signal which, in turn, is used by a positioning drive including an electric servomotor to drive the rotary drive. The positioning drive includes a servoamplifier and a microprocessor for generating commands for controlling the servoamplifier in response to the reference central signal. The PLC also controls a hydraulic control unit which controls the axial position of the index table relative to a base of the assembly.

Abstract: A linear drive for articulated furniture having pre-determined extended and retracted positions. These devices heretofore have been designed to be adjustable, but customer adjustment frequently causes costly damage to the drive and furniture. The drive includes a motor-driven rotary screw and a cooperating nut carrying drive tube which is rotationally fixed to a drive housing to prevent customer adjustment.

Abstract: A drive assembly for a valve includes a motor, a transmission which is coupled to the motor and the valve, and a manual drive unit having a shaft which is arranged to be driven by a handwheel. The shaft has a small amount of axial play and is provided with a worm. The transmission includes a hollow gear having internal teeth coupled to the motor shaft and external teeth in permanent mesh with the worm. A membranous disc is mounted on the worm shaft in such a manner that the outer margin of the disc is held against displacement in axial direction of the worm shaft while the central portion of the disc adjacent the worm shaft is fixed against axial displacement relative to the worm shaft. However, the worm shaft can rotate relative to the disc. Strain gages in the form of strips are mounted on one side of the disc and are connected to an integrated circuit on the same side of the disc.

Abstract: A linear actuator of the present invention includes a hollow drive tube. A slip clutch having front and rear camming surfaces is housed in the tube for rotation about an longitudinal axis. The slip clutch is axially fixed in the tube by a shoe. The slip clutch threadably receives a threaded shaft which is connected to a gear motor to be driven thereby. The shaft has stop nuts at either end, each of which has a camming surface which mates with a respective camming surface of the slip clutch. When the shaft is rotated by the motor, it rotates in the slip clutch. The slip clutch frictionally engages the drive tube, via the shoe, so that the tube will move linearly. When the slip clutch is engaged by one of the stop nuts, the slip clutch will free wheel in the tube and the tube will cease its linear movement. The slip clutch will continue to rotate in the tube till the motor is stopped or its direction is reversed.

Abstract: A jack mechanism having a crank handle that drives a linear motion control all nut and threaded screw. Two rods are included to provide a positive stop in each direction of the jack's limit so as to prevent overrun of the mechanism.