Abstract: A wheel jack holder for a vehicle may include a holder base having at least one sliding member formed at each of first and second side portions of the holder base, whereby a wheel jack is configured for being placed on the holder base; and a pair of holder arms, each having a sliding rod formed at a first surface thereof, wherein the sliding rod is slidably inserted into a hole of the sliding member. The pair of holder arms may move away from each other when receiving force from the wheel jack to be fixed to a wheel rim of a wheel.

Abstract: A multilinear actuator transmits a force in several directions, and includes complementary actuating strands made of flexible material and provided on a first face with spaced studs, the actuating strands being located opposite each other, the studs meshing with one another, and transverse faces of one stud bear against respective rear and front transverse faces of adjacent studs of the other actuating strand, defining a straight section in which the two actuating strands are rigidly connected, so that the straight section behaves like a rigid bar, said actuating strands including on an outer face, regularly spaced teeth, the actuator including one driving member per actuating strand, meshing with the teeth of the second face of one of said actuating strands to translate said actuating strand, the actuator including a straight section and a straight section in which the actuating strands are meshed, and a curved region located between the straight sections in which the actuating strands are spaced apart.

Abstract: Actuation systems and methods for actuating a telescopic structure are provided. The actuation system can include a chain cartridge including a drive chain engageably coupled to a drive mechanism actuated by an actuator coupled to a power supply. The drive chain can include a plurality of inter-connected links conveying at least one cable within an interior space of each inter-connected link. The system can also include a telescopic structure including a plurality of segments configured to extend and retract telescopically and conveying the drive chain therein. The drive chain can couple to a distal segment of the plurality of segments. The drive mechanism can impart a linear translation force on the plurality of inter-connected links to cause the distal segment to extend or retract from the telescopic structure. Methods of actuating the actuation system described herein are also provided.

Abstract: A hinge pin remover for removing a hinge pin from a door hinge assembly. A geared wheel is rotatably connected to a hinge pin remover body. The geared wheel includes a plurality of geared wheel teeth. A handle is rigidly connected to the geared wheel. A geared shaft extends through the remover body. The geared shaft includes a plurality of geared shaft teeth. The geared shaft teeth are engaged with the geared wheel teeth. A lower push rod is connected to the geared shaft and is for pushing the hinge pin as the geared wheel is rotated. A forked clip is slidingly connected to the geared shaft and is for pulling the hinge pin as the geared wheel is rotated.

Abstract: Provided is a steam turbine overspeed protection system, includes a drive gear arranged to match a rotation speed of a rotor of a steam turbine; a rotating shaft parallel to an axis of the drive gear and capable of rotating at a critical rotation speed; a protective gear arranged on the rotating shaft and forming a lead screw nut mechanism with the rotating shaft, and arranged to be capable of engaging with the drive gear when the rotation speed of the drive gear exceeds the critical rotation speed; and an operating rod connected to the protective gear; wherein, when the drive gear engages with the protective gear, the protective gear can move in the axial direction of the rotating shaft and thereby drive the operating rod to move and produce an action that activates a protection device for preventing steam turbine overspeed.

Abstract: A vertically movable workpiece support device has a ratchet wheel with a larger diameter than the outer diameter of a driving sprocket wheel and is concentrically attached to an end surface of a boss portion in the driving sprocket wheel. A pair of left and right bearing members are provided side by side, on a side on which the free end side of a drive chain is horizontally extended with respect to the driving sprocket wheel, so as to sandwich a horizontally extending path section of the drive chain. A movable pawl is pivotally supported between the pair of left and right bearing members and engages with the ratchet wheel to block the rotation of the ratchet wheel caused by the movement of the drive chain when the workpiece support base is lowered. An actuator switches the movable pawl to a non-action position with respect to the ratchet wheel.

Abstract: A method and apparatus for activating a vehicle's brake pedal for testing proper operation of the vehicle's brake lights and/or for testing for an air leak in the vehicle's air brake system. The method and apparatus can be advantageously employed by a single operator of the vehicle without need for assistance from another person.

Abstract: A wireless communication casing is an apparatus that conceals wireless communication equipment while maintaining the signal communication between wireless communication equipment and corresponding wireless communication devices. The apparatus includes an upper capsule, a lower shroud, a tubular housing, a stopper, a mounting pole, a support post, and a pulley assembly. The upper capsule covers the tubular housing which surrounds the mounting pole. The lower shroud upholds and encloses the tubular housing. The stopper upholds the mounting pole above the support post. The mounting pole serves as a platform to mount wireless communication equipment. The support post elevates the mounting pole and consequently the wireless communication equipment above the ground. The pulley assembly raises and lowers the tubular housing and the lower shroud along the support post. The pulley assembly facilitates the accessibility of the wireless communication equipment.

Abstract: A flex-drive actuator for a satellite boom hinge or other hinge applications. Using a motor-driven cog and a unique drive chain, the hinge can be reversibly driven between open and closed positions, thereby deploying or stowing the boom and attached payload. The chain includes links designed so that, when bent in one direction, the chain pre-buckles into a rigid circular arc form that matches the deployment path of the hinge. This pre-buckling essentially converts the chain into a rigid gear segment that can carry a moment to actuate the hinge. As the cog retracts the chain and the hinge closes, the circular shape of the chain de-buckles on the free side of the cog, where the chain can be stored as a straight section inside of a boom tube or folded into a magazine. The flex-drive actuator can accommodate any desired actuation angle by addition of links to the chain.

Abstract: Disclosed are a canister type thruster for implementing smooth upward/downward movement and improving productivity and an installation method thereof. The canister type thruster includes a guide module for guiding upward/downward movement of a canister. The guide module includes: a guide unit that is installed on an inner surface of a trunk so as to support a rack installed on an outer surface of the canister in parallel with a lifting direction to guide the upward/downward movement of the canister; a sliding pad that relieves an impact or a friction applied to the guide unit; and a support protrusion that is provided between the guide unit and the sliding pad to support the sliding pad.

Abstract: A multi-joint arm mechanism includes an arm supporting member a first, second and third joints. The third joint has a linear extension and retraction axis. The third joint includes flat-shaped first structures bendably coupled to one another, second structures having a C-shaped section and bendably coupled to one another, a supporting member supporting the stiffened first and second structures, and a drive member sending and drawing the stiffened first and second structures. The first and the second structures are linearly stiffened by being in contact with each other and return to a bent state by being separated from each other. The second structures are bent toward the bottom parts and conveyed into the arm supporting member. The first structures are bent in a same direction as the second structures and conveyed into the arm supporting member. The first structures are stored in the arm supporting member along the second structures.

Abstract: A platform system for self-leveling a stage is provided and includes one or more module assemblies and one or more supports. Each module assembly includes one or more receiving members for engaging and removably securing the one or more supports. Each support includes an elongate portion, an extendible portion extendible from and lockingly engageable with the elongate portion, a base member removably attached to the extendible portion, and an actuator assembly secured to the elongate portion and in communication with the extendible portion. The actuator assembly is configured to rapidly extend and lockingly engage the extendible portion and the base member to provide self-leveling of each of the one or more module assemblies of the stage as the base member engages an underlying surface.

Abstract: Embodiments described herein may include at least one pole including a plurality of projections disposed at incremental heights along the pole, an object, a first pulley positioned on a first side of the object, and a second pulley positioned on the second side of the object.

Abstract: An optical axis adjusting screw (15) is provided with a shaft portion (16), a gear portion (17), and an elastic engagement portion (18). The elastic engagement portion (18) is provided with a base end (18BE) and a free end (18FE). The base end (18BE) is fixed to the shaft portion (16). A distal end face (18a) is formed at the free end (18FE) and is substantially perpendicular to an axial direction of the shaft portion (16). There is no parting line on the distal end face (18a).

Abstract: An automatic extensible telescopic apparatus includes an internal tube inserted in an external tube. A positioning unit includes a ferrule, two fins, an axle, a toothed wheel and a first detent. The ferrule is provided on the external tube. The fins extend from the ferrule. The axle is supported on the fins. The toothed wheel is supported on the axle and includes teeth for insertion in recesses defined in the internal tube. The first detent is supported on the fins for engagement with the toothed wheel. A handle includes two leaves and a second detent. The leaves are placed between the fins and supported on the axle. The second detent is supported on the leaves for engagement with the toothed wheel. An extending unit is connected to the axle so that the extending unit rotates the toothed wheel via the axle, thus extending the internal tube from the external tube.

Abstract: A system and method for partially or completely inverting (rotating) a die and subsequently returning the die to its normal operating position. Systems of the invention include a roll-over unit that engages a roll frame or similar structure to which a die of interest is temporarily secured. The roll-over unit includes a drive motor that is used to rotate the roll frame and the die that is releasably coupled thereto. A deceleration assembly is provided to bring rotation of the die to a slow and controlled stop in one or both rotational directions. When the drive motor is a hydraulic motor, the deceleration assembly may include deceleration valves that are actuated by a rack gear that is caused to move linearly during rotation of the drive motor.

Abstract: A lift system comprising an elongated rack and a roller pinion drive system. A preferred version has two parallel rack with plurality of rungs extending horizontally between the racks to form a ladder. A plurality of spaced apart mounting brackets are configured for affixing the ladder vertically to a stationary member, the stationary member not forming part of the invention. In this version, a drive unit retained within a carriage is mounted in proximity to the racks. The drive unit interacts with the racks to move the carriage upwardly and downwardly along the racks. A speed limiter is also disclosed that can be retained within the carriage below the drive unit and mounted in proximity to one of the racks. The speed limiter interacts with the rack to produce a breaking action if the drive unit fails, preventing the carriage to drop down quickly. Single rack and inclined rack versions are disclosed as alternatives.

Abstract: The present invention relates to an apparatus for transferring an object from a lower accessible position to a higher storage position, which is particularly useful on vehicles. The present invention also relates to a method of transferring an object from a lower accessible position to a higher storage position.

Abstract: A motion transmitting drive chain (drive chain) is prevented from buckling by applying a relatively small compressive bias force to one side of the pins around which the chain links rotate. The bias force is applied on the locking projection side of the pins axes of rotation such that the links are urged to rotate in the direction required to lock them against each other.

Abstract: A jack bar includes an outer tube, an inner tube and a positioner tube coaxially located. The positioner tube is extendable to adjust a length to the jack bar in use while enabling the jack bar to be retracted for storage. The jack bar further includes a clamp configured to receive tubes of various shapes. The clamp is further configured to prevent twisting or turning of clamped tubes.

Abstract: The present invention provides a rack and pinion mechanism which avoids collision between respective tooth tops of a rack gear and a pinion gear due to a phase shift between the rack gear and the pinion gear with a simple mechanism and meshes the rack gear and the pinion gear smoothly. The rack and pinion mechanism includes a rack gear 16 fixed to a stage 20 moving on a carrying track 7 while loading a carried object thereon and a plurality of pinion gears 17 connected to a drive source 13. At least two of the pinion gears are synchronized and rotate to mesh with the rack gear in sequence, whereby the rack gear is delivered from the pinion gear in the current process to the pinion gear in the subsequent process, so that the stage is carried.

Abstract: The invention relates to a lifting apparatus for use in a transport vehicle to lift a load at a height of a loading space of the vehicle, wherein the lifting apparatus comprises: a guide member provided with rails, wherein a movable displacement unit is mounted, a rack of a rack-and-pinion arrangement provided within the guide section and wherein the rack-and-pinion arrangement engages with the displacement unit, a carrier section that extends along a main axis and wherein said carrier section is connected at its first end to the displacement unit, a positioning surface connected to an opposite end of the carrier section to position a load for lifting a force compensator which exerts a force on the carrier section, essentially in the direction of the longitudinal axis thereof in order to bear at least a portion of the weight load.

Abstract: A jack bar includes an outer tube, an inner tube and a positioner tube coaxially located. The positioner tube is extendable to adjust a length to the jack bar in use while enabling the jack bar to be retracted for storage. The jack bar further includes a clamp configured to receive tubes of various shapes. The clamp is further configured to prevent twisting or turning of clamped tubes.

Abstract: A coupling device for two connecting poles which includes: a lower fixing sleeve sleeved on the upper portion of a lower connecting pole, having an opening communicating the outer surface and the inner surface of the lower fixing sleeve, two fixed plates extend outwards from the edge of the opening; an upper fixing sleeve having a through gap, two fixing plates extend outwards from the gap, the fixing plates of the upper fixing sleeve are disposed within the lower fixing sleeve, the fixing plates including releasing portions and locking portions; a controlling member rotatably connected to the lower fixing sleeve, including a central portion and two side portions, the inner side surfaces of the two side portions contacting the outer side surfaces of the two releasing portions.

Abstract: A jacking method and apparatus for a heavily loaded platform includes hydraulic continuous linear motion motors, preferably comprising a plurality of phased hydraulic piston/cylinder units, that are engaged to drive the heavily loaded platform to provide relative motion of the platform with respect to a platform support, and to also hold the platform in a selected stationary position. In the preferred jack-up system, the number of hydraulic piston/cylinder units and the number and design of the teeth that are engaged in providing relative motion may be combined to substantially reduce material stresses on the system.

Abstract: In a jacking system for a marine platform, a plurality of hydraulic continuous linear motion motors are engageable with a plurality of marine platform supporting logs to provide relative motion between the platform and its supporting legs, and to also maintain the platform and its supporting legs locked in a stationary relationship. In the jacking system, the number of hydraulic piston/cylinder units and the number and design of the teeth that are engaged in providing relative motion may be selected to substantially reduce material stresses on the system.

Abstract: A support device is used to facilitate maintenance of a jacking system of a self-elevating drilling or maintenance platform having a plurality of legs supporting the platform in an operating orientation. The platform includes jacking mechanisms associated with the legs to raise and lower the platform using jacking racks on each leg chord. Support devices temporarily support the platform independent of the jacking mechanisms using a rack chock removably clamped in place on each leg with locking teeth on the rack chock meshed with jacking teeth on the leg's jacking rack. In this manner the platform can be temporarily supported by using removable fasteners to secure a rack chock to each leg chord beneath the platform hull, lowering the platform relative to the legs so that the hull rests on a support seat on each support device, and then disengaging the jacking mechanism from the jacking teeth on the legs for maintenance of the jacking system.

Abstract: A mobile offshore drilling unit (MODU) jacking system includes a plurality of hydraulic continuous linear motion motors, preferably comprising a plurality of phased hydraulic piston/cylinder units, that are engaged with a plurality of MODU supporting legs to provide continuous relative motion between the MODU platform and its supporting legs, and to also maintain the MODU platform and MODU supporting legs locked in a stationary relationship. In the preferred jack-up system, the number of hydraulic piston/cylinder units and the number and design of the teeth that are engaged in providing relative motion may be combined to substantially reduce material stresses on the system.

Abstract: A rack-type lift for vehicles includes a first, stationary rack and a second movable rack that supports a lifting unit. A toothed wheel that is movable within the lift between a first and second end position is interposed between the racks, which racks are so positioned relative to the toothed wheel that opposite ends of these racks engage the toothed wheel at the different of travel positions of the toothed wheel. Thereby, the lifting unit of the vehicle lift travels a distance twice as large as the toothed wheel.

Abstract: A drive system for elongate members comprising a drive plate, a support system, an insertion housing, at least one drive gear, and a vibratory system. The suppression system resiliently opposes relative movement between the support plate and the insertion housing. The drive gear displaces the elongate member along its longitudinal axis. The vibratory forces are transmitted to the elongate member through the at least one drive gear. The drive gear and the vibratory system simultaneously crowd and vibrate the elongate member into the ground.

Abstract: A nail removing apparatus for removing and holding nails. The nail removing apparatus includes a housing having a bottom wall, a front wall, a back wall, a pair of side walls and a top wall. The bottom wall has an opening therein extending into the interior. A foot portion is integrally coupled to the bottom wall and includes a pair of tines adapted for positioning under a head of the nail. A lifting apparatus lifts a nail and includes a saddle positioned in the housing. A first plate is slidably mounted on the saddle and is extendable through the opening in the bottom wall. A second plate is integrally coupled to a bottom edge of the first plate and has a pair of prongs thereon for lifting a nail from the foot portion. A motor is mechanically coupled to the first plate for selectively retracting and extending the first plate.

Abstract: A system for displacing an elongate member relative to the ground. The system includes a drive rack, a support assembly, a vibratory assembly, and a drive assembly. The vibratory assembly comprises a vibratory housing defining a vibratory chamber and a vibratory axis and a vibratory system mounted within the vibratory chamber to generate a vibratory force along the vibratory axis. The drive assembly comprises a drive housing comprising a main portion defining a drive chamber and, in certain configurations, a sleeve portion defining a sleeve chamber, where a drive axis extends through the drive chamber and the sleeve chamber and a drive system mounted within the drive chamber and comprising a drive gear that rotates to generate a drive force along the drive axis. The vibratory housing is mounted onto the support assembly to reduce the transmission of vibratory forces from the vibratory housing to the support assembly.

Abstract: A derrick, especially a drilling rig derrick, including a derrick structure and lifting tackle for a load, for example, a drill string, in the derrick structure.

Abstract: A post pulling apparatus for pulling and removing posts from a ground. The post pulling apparatus includes a base assembly having a base member and having a plurality of wheel members securely mounted to the base member; and also includes an elongate support member being vertically disposed upon the base member and having an open top end and a bore extending therethrough; and further includes a post pulling assembly for pulling a post out of a ground.

Abstract: A lifting device enabling loads to be lifted over long distances, characterized in that it comprises a housing fitted with two rotary pinions driving an articulated lifting column and comprising two parallel articulated sides joined by means of connecting shafts, each side comprising two contiguous rows of essentially rectangular plates place end to end to end in a same row and longitudinally offset one row from another the plates of one row being applied against the plates of the contiguous row and having a front active face and a rear active face which move to bear respectively against the rear and front active faces of the adjacent plates when the section of lifting column comprising the plates is vertically extended.

Abstract: An apparatus for pushing tubular members along a tunnel, the apparatus comprising a frame shaped to receive a tubular member therein and having an open end shaped to receive the tubular member therethrough, and a pushing element mounted on and displaceable along the frame for engaging a tubular member within the frame and pushing the tubular member along the frame and through the open end. The apparatus further includes a drive motor mounted on the pushing element and engaging the frame, the drive motor displacing the pushing element along the frame relative to the open end.

Abstract: A windshield lift acting between the floor of a vehicle and the inside surface of the windshield with the aid of suction cups to apply an outward force to place the seal which bonds the windshield to the vehicle frame under tension. The peripheral seal can then be easily cut with a knife.

Abstract: There is provided a guide roller assembly for use in a wastewater treatment facility comprising a pin and a guide roller, wherein the guide roller directly surrounds the pin and the pin rotates within the roller. There is also provided a guide roller assembly for use in a cog rake bar screen comprising a pin and a guide roller, the guide roller surrounding the pin, wherein the guide roller comprises a low-friction polymeric material and the pin rotates within the guide roller, the guide roller being free to rotate.

Abstract: A system for inserting elongate members into and removing elongate members from the ground. The system is a bottom drive system that is capable of applying crowding or extraction forces to the elongate member while at the same time vibrating the elongate member along its axis. A vibratory assembly is mounted by a shock absorbing assembly to a support base. A gear or other type of drive assembly is mounted on the vibratory assembly. Vibratory forces generated by the vibratory assembly are applied to the elongate member through the drive assembly, causing the drive assembly to vibrate with the elongate member. The elongate member extends through the center of the vibratory assembly such that the vibratory forces have a vibratory axis that is aligned with the lengthwise axis of the elongate member to prevent torsional or twisting forces from being applied to the elongate member.

Abstract: There is provided a guide track for cog rake bar screens comprising a metallic or nonmetallic guide track. There is also provided a guide track for cog rake bar screens comprising modular sections of guide track being disposed adjacent one another wherein guide rollers are guided within the guide track.

Abstract: A mechanical lifting jack. The jack includes a single gear rack having a single row of spaced-apart teeth. A gear member having two pin members is held in meshing engagement with the gear rack by a gear housing circumscribing the gear rack. The teeth of the gear rack collectively define a teeth profile line. The gear member is rotatable about an axis of rotation, and is held by the gear housing such that the axis is maintained interiorly of the teeth profile line as the gear member operates and engageably advances along the gear rack. The pin members preferably reside on opposing sides of the axis of rotation and the teeth are sufficiently long to define gaps therebetween that are longer than diameters of the pin members, structural conditions which combine with the position of the axis to enable the pin members to impose forces against and normal to upper surfaces of the teeth.

Abstract: The invention concerns an improved device in pallet loaders, comprising an upright frame (1) and a pair of horizontal lifting fork members (2) which may be raised and lowered together with said frame (1) by means of a lifting mechanism. The lifting fork members (2) are equipped at their outermost end with one support wheel (4) each, which wheels are attached to an articulated arm (14) arranged to be pivoted downwards. The frame (1) and the lifting fork members (2) may be raised and lowered by means of a rack (6) which is connected via a cable, wire on chain (10) to an articulated, two-armed rocker arm (13). In turn, the latter is connected to the articulated arm (14) by means of a traction rod (15) which is associated with the arm (14). Upon upwards motion of the rack (6) and thus of the frame (1) a pulling force on the cable (10) will be transferred via the rocker arm (13) and the traction rod (15) to the articulated arm (14), which then swings downwards, thus raising the lifting fork members (2).

Abstract: A device for releasing of a frozen screw pressed against a contact surface uses a compression disc pre-loaded to an anticipated amount of deflection prior to mounting between the contact surface and the screw. The disc has an insert formed from a granulated material mixed with a water soluble binder, allowing to wash out the insert and cause collapse of the disc, so as to break the connection between the contact surface and the screw.

Abstract: A locking mechanism is disclosed for use on the legs of a jack-up offshore platform. Each chord of the legs includes a rack for cooperation with pinions used in raising and lowering the legs. The locking mechanism of the invention includes a rigid frame attached to the hull of the platform and housing a plurality of vertically aligned toothed chock segments adapted to engage the teeth of the rack on a leg. The chock segments have upper and lower inclined surfaces which cooperate with upper and lower movable wedges for supporting the chock segments. The design makes the chock segments sufficiently adjustable for independent alignment and engagement of the teeth of each chock segment with the corresponding teeth of the rack. Dimensional variances in the rack teeth spacing, resulting from manufacturing tolerances, thereby are accommodated and force concentrations between the rack teeth and chock teeth are minimized.

Abstract: A mechanical drive assembly composed of an endless roller chain (78) and notched rail (100) wherein multiple chain rollers (79) engage corresponding rail notches (103 ) to securely interlock drive (38) and rail (100). Drive (38) is equipped with a triple-strand roller chain (78) whose center strand of rollers engage notched bar (102) while outer strand rollers roll across face of pressure plate (50). Drive assembly (38) may be held in a fixed position relative to a static rail (100) by applying a braking force to drive sprocket (76), or it may be moved tangentially to rail (100) by applying torque to drive sprocket (76). Conversely, rail (100) and any structure attached thereto may be held in a fixed position or moved tangentially relative to a statically mounted drive (38) by similar means.

Abstract: A device for positioning cargo includes a rack slidably engaged in a tube and outstretched from the tube so as to force against the cargo in order to position the cargo within a container, a base is secured to the tube, a ratchet gear is rotatably supported in the base and engaged with the rack, a handle is pivotally coupled to the base and has a catch engaged with the ratchet gear, the rack can be easily and quickly outstretched from the tube when the handle is rotated in a reciprocating action.

Abstract: An apparatus for lifting an object for working therebeneath comprising a pair of parallel side plates having apertures through their upper ends and with a pin extending through the apertures. A base comprised of feet is secured with respect to the lower ends of the side plates. The base also has a forwardly extending foot. A sprocket is secured to the pin for rotation about an axis coincident with the axis of the pin with the sprocket having teeth extending radially therefrom. A chain is positioned over the sprocket with the links of the chain sequentially positionable with the teeth of the sprocket through the chain. A lifting plate is positionable in a lower orientation with a lifting surface. The lifting plate has an upwardly extending attachment member. A pedal has an interior end reciprocable between an elevated location and a lowered location. The pedal has an upwardly extending attachment member secured with respect to the second free end of the chain with a locking component.

Abstract: A telescoping support has at its actuating head at which a roller engages a bar which emerges from the outer tube, a sleeve-like extension provided with a pawl which can engage the bar in a sleeve-locking manner under load to prevent spontaneous contraction of the support upon rupture of the roller.

Abstract: An elongatable support has a lever actuating a fork for displacing a roller out of wedging engagement between an inclined surface of a head on a tube from which a bar can telescopingly extend, and a surface of this bar. To prevent inadvertent actuation of the lever, an abutment is interposed between the lever and the tube and can be withdrawn manually against gravitational and/or spring force to allow actuation of the lever.

Abstract: The device comprises at least one rod normally locked by notched rollers mounted on pins and cooperating with at least one V-shaped bearing plate having toothed ramps, and the vertical displacement of which is made by rotation of a cam driven by a set of studs rigid with a circular member, with control means being further provided to drive this circular member.