Abstract: An adjustable furniture assembly having a support structure for receiving a bridge of the furniture assembly is described. The support structure includes a horizontal support member which receives the bridge in a slidable engagement to provide the furniture assembly with adjustability in a right or left direction. The horizontal support member is further adjustable to provide the furniture assembly with adjustability in a vertical direction.

Abstract: An adjustable width wire shelving unit has at least one first shelf and at least one second shelf. Each shelf has an elongate front wire, an elongate rear wire, and a plurality of transverse wires connected and extending between the respective front and rear wires. The front and rear wires extend a width of their respective shelf. The first shelf is sized to overlap and nest with the second shelf over a desired fraction of its width. The transverse wires of the overlapped first and second shelves lie in essentially the same plane to form a support surface.

Abstract: An adjustable support assembly for a data entry/interface device for computers or the like such as a keyboard, keypad, laptop/notebook computer, personal data/digital assistant, tablet PC, trackball or the like provides selective adjustment of both height and angular orientation or tilt for the data entry/interface device with respect to the work surface on which it is mounted. A pair of actuator handles are pivotally mounted in close proximity to one another on a data entry/interface mount to allow either independent or simultaneous operation with one hand by the device operator to control height and/or tilt. The actuator handles are connected to individual adjustment clamp assemblies by separate flexible cable actuators. Depression of each actuator handle pivots at least one clamp bar connected to the cable actuator between clamping and release positions to lock or allow reciprocation of a rigid adjustment bar extending through an aperture in the clamp bar.

Abstract: A computer desk for either right-hander or left-hander is disclosed. The desk comprises two first crosspieces interconnected legs at both side, second and third crosspieces interconnected both sides, two links moveably mounted on the first crosspieces, a connecting member moveable along the links, a latch at the connecting member, a printer support on top of the links, a keyboard tray, a hole in each leg, and a computer platform releasably secured to the holes from one of inner and outer locations at either side of the desk. For adjusting the print support and the tray, unfasten the second crosspiece by pivoting the latch upward, slide the links along the first crosspieces and the tray along the third crosspiece to left or right side of the desk, and fasten the second crosspiece by pivoting the latch downward.

Abstract: A furniture construction includes a frame structure made up of a pair of spaced frame sections connected together, and a furniture component mounted to the frame structure. Each frame section includes a lower base section, an upright, and a furniture component support member extending from the upright and to which the furniture component is mounted. The frame sections are preferably C-shaped when viewed from the side. In one form, the furniture component is a seat mounted to the furniture component support, and the frame structure includes a back support area extending upwardly from the seat. A back is mounted to the back support area. In another form, the furniture component is a desk or table top mounted to the furniture component support. Combination desk/chair units may also be constructed utilizing the same basic frame structure.

Abstract: A shelf stores items and provides for organized and attractive display with ease of item access. Conforming to a defined physical environment or variable storage space optimally requires the shelf to provide for both vertical and horizontal adjustment. Here this is accomplished by a pair of legs that are telescopic (to reduce size) and can be locked at a height (vertical adjustment) by use of a pawl, pin, screw or other fastener known in the art. The shelf includes a planar surface that is comprised of a shelf portion, which is supported on each distal end by a leg extension. The leg extensions are mounted to the upper area of the legs. The leg extensions are received by the shelf portion, being movably mounted thereto. This allows for horizontal (width) adjustment. An end cover can be used to provide a flat surface that is consistent with the upper surface of the shelf portion.

Abstract: A workstation table includes at least two horizontally oriented spaced worksurface struts which allow a work platform to be placed atop the worksurface struts to extend between them. Leg struts having adjustable length extend downwardly from the workstation struts, and a crank link extending between the leg struts can be rotated to adjust the length of both of the leg struts simultaneously. Base struts extend from the ends of the leg struts opposite the worksurface struts to better support the base struts. Stabilizer struts, which also preferably have adjustable length, extend between the opposing base struts and/or between the opposing leg struts to help maintain them in spaced relation. The various struts are made of tubing and are affixed together with strut clamps formed of clamp shells, with each clamp shell being shaped to complementarily fit about portions of adjoining struts in such a manner that the clamp shells may be affixed about the adjoining portions to attach them together.

Abstract: The invention is directed to a tray which includes a base having an upwardly opening open-ended groove and a member slidable in the groove for limited right-to-left and left-to-right movements in a horizontal plane. Upper surfaces of the base and the slidable member lie substantially in a common plane such that at least two input devices, such as a keyboard and a mouse, can be supported thereon on substantially the same horizontal plane.

Abstract: A forearm/wrist/mouse support system comprises a panel formed in a generally rectilinear configuration having a front, rear, and lateral side edges and a lower surface positionable on the upper surface of the desk. A recess of a generally rectilinear configuration is formed in the panel and extends upwardly from its lower surface to a location adjacent to the upper surface. A support plate in a generally rectilinear configuration for the arm and wrist of a user and a computer mouse has a top, a bottom, a front, a back and parallel sides and is slidably received within the recess for movement between an operative orientation wherein it is pulled forwardly to overlie a portion of the desk and also forwardly of the desk and an inoperative within the recess.

Abstract: A portable mechanic's bench removably spans vehicle hood ledges having lateral flanges extending from upstanding fender components bordering the vehicle engine compartment and may comprise a tray with an open top. A pair of drawers with open tops are laterally telescopically received by the tray to be movable from a first position in which the drawers are in laterally inward storage position to an outwardly extended operative position. Legs diverge downwardly and laterally outwardly to exert wedging stress on the fender upstanding components to hold the bench in position.

Abstract: A storage rack with vertically arranged, horizontal drawers movable by a crank mechanism is provided. Each individual drawer of the storage rack has a gear mechanism which is connected to a drive shaft with wheels. A crank handle is provided to engage the gear mechanism of any individual drawer and provide motive force to the drive shaft. The rotation of the crank causes the drive shaft to rotate and, in turn, rotates the wheels. The wheels travel along respective track members attached the storage rack to move a drawer in and out relative to the storage rack.

Abstract: A table support device includes a base having two parallel tracks, one or more bars and a board slidably engaged on the tracks, one or more followers slidably coupled to the tracks with poles and movable toward and away from the board, for increasing a distance between the followers and the board, and for supporting longer work pieces. One or more guide rods may be slidably engaged in the board and the bars for stably guiding the board to move relative to the bars. One or more support members of different areas are supported on the bars for supporting various kinds of work pieces.

Abstract: A refrigerator shelf comprising a plate surrounded by a frame to which there are connected guide means for the slidable guiding of a closure member formed from an assembly of hinged-together bar elements which is able to pass between an extended position in which it closes a chamber formed between said shelf and an underlying shelf, and a retracted position into the guide means.

Abstract: A two-axis stage assembly includes a generally planar horizontally mounted base plate; a stage plate generally parallel to the base plate, the stage plate having a first axis and second orthogonal axis; a set of spaced bearings depending from a bottom surface of said stage plate, the bearings each having an arcuate bottom surface in rocking contact with a facing support surface of the base plate; a joint attached to the bottom surface of the stage plate and pivotably mounting each bearing, the joint being positioned at the center of curvature of the arcuate bottom surface of the associated bearing; and where an axial movement of the stage plate rocks the bearing arcuate bottom surfaces with respect to the facing support surface of the base plate.

Abstract: A two-axis stage assembly includes a generally planar horizontally mounted base plate; a stage plate generally parallel to the base plate, the stage plate having a first axis and second orthogonal axis; a set of spaced bearings depending from a bottom surface of said stage plate, the bearings each having an arcuate bottom surface in rocking contact with a facing support surface of the base plate; a joint attached to the bottom surface of the stage plate and pivotably mounting each bearing, the joint being positioned at the center of curvature of the arcuate bottom surface of the associated bearing; and where an axial movement of the stage plate rocks the bearing arcuate bottom surfaces with respect to the facing support surface of the base plate.

Abstract: An apparatus and method for assisting an individual, particularly a physically and/or mentally handicapped person, in performing a paper manipulating task includes a base which supports a paper manipulating unit, such as an electric stapler, hole punch, folding mechanism or the like, as well as a platform. In the most preferred form, the platform is vertically adjustable relative to the base in order to enable positioning the platform at a height commensurate with a paper receiving zone associated with the selected paper manipulating unit. A paper tray, selected from a group of trays depending on the particular paper manipulating task desired to be performed, is provided atop the platform for movement between a paper loading position, wherein one or more sheets of paper are arranged in the tray, and an operating position, wherein the one or more sheets are delivered to the paper manipulating unit.

Abstract: A tabletop assembly (20) for securing articles against high acceleration loads includes a substantially planar tabletop (22) having a top surface (24) and an opposite bottom surface (26). At least one article-receiving track (28) is inset into the top of tabletop (22). A brace (36) is disposed beneath the tabletop (22) and connected to the track (28) so that the track (28) will not separate from the tabletop (22) under high acceleration loads such as from a seismic event.

Abstract: The present invention relates to a two-dimensional motion producing apparatus for converting rotation of an input shaft to a two-dimensional motion in an X-direction of an output member and in an Y-direction orthogonal thereto.

Abstract: A feeding apparatus provides a base; a movable body elongated in a longitudinal direction orthogonal to a moving direction of the movable body on the base; a pair of linear guide devices arranged on the base in parallel with each other, for guiding the movable body in the moving direction; a linear drive device mounted on the base for moving the movable body along the linear guide device; and an attitude stabilizing device mounted on the base for restraining a yawing motion of the movable body, the attitude stabilizing device including at least one transmission member, first and second fastening points formed in the movable body for fixing the transmission member, the first and second fastening points being separated from each other in the longitudinal direction, and first and second direction-changing devices mounted on the base and separated from each other in the moving direction.

Abstract: A portable, self mounting shelf is made of a plurality of generally tubular legs and cross members. A first adjustable leg and second adjustable leg are held within the same horizontal plane by a center adjustable crossbar and a rear adjustable crossbar. A holding foot is affixed each to the first leg and the second leg at the end opposite the rear crossbar. Pivotal attachment are included capable of allowing rotation of the legs about the crossbars in a pivoting manner along the same horizontal plane.

Abstract: A high accuracy, orthogonal motion stage for microscopes and the like uses three frames for orthogonal motion. The lower most frame has provided thereon a series of downwardly depending ramps. An actuator plate having correspondingly positioned, upwardly directed ramps is translated with respect to the lower most frame to raise and lower the frames.

Abstract: A shaking table assembly includes a plurality of first linear guides arranged in parallel with each other. A supporting table is slidably mounted on the first linear guides along a longitudinal direction thereof. A plurality of second linear guides are fixedly mounted on a top surface of the supporting table and are arranged in parallel with each other and perpendicular to the plurality of first linear guides. A testing table is slidably mounted on the second linear guides along a longitudinal direction thereof.

Abstract: A storage shelf for use in an extended cab type pickup is disclosed. The shelf consists of a folding tray having extendable outer edges for adjustment to fit most models of extended cab pickups. The shelf is laterally secured at either end to the interior molding of the pickup by the use of notches which fit into the contours of the molding. The surface of this shelf is surrounded by rails which extend around the outside of the tray. The effect of this is to provide an easily accessible place to store personal items. In addition, the lateral strength of the present invention is enhanced by the use of hinge braces, a rear side support block which helps support the rear edge of the shelf, and a support leg which extends from the front edge of the shelf to the floor of the pickup. These features allow for the storage of heavy objects on the present invention.

Abstract: A feeding apparatus provides a base; a movable body elongated in a longitudinal direction orthogonal to a moving direction of the movable body on the base; a pair of linear guide devices arranged on the base in parallel with each other, for guiding the movable body in the moving direction; a linear drive device mounted on the base for moving the movable body along the linear guide device; and an attitude stabilizing device mounted on the base for restraining a yawing motion of the movable body, the attitude stabilizing device including at least one rope member, first and second fastening points formed in the movable body for fixing the rope member, the first and second fastening points being separated from each other in the longitudinal direction, and first and second direction-changing devices mounted on the base and separated from each other in the moving direction.

Abstract: A system for rehabilitating a speech impaired individual confined to a wheelchair is disclosed. The system utilizes an arm movement actuator attachment which is secured to the arm rest structure of the wheelchair through a rotatable arm support platform mounted on juxtaposed, upper and lower slide rod assemblies providing X- and Y-axis movement for the rotatable platform. The platform is configured to fully support the individual's forearm and elbow to enable the individual suffering from minimal upper extremity mobility to physically contact a touch screen for enablement of interaction with a computer to communicate and therefore socialize with others.

Abstract: An adjustable keyboard holder has a keyboard support. Relative to a horizontal work platform, the keyboard support is slidably extensible from a storage position to a working position and is retractable therefrom. In the working position, the keyboard support is vertically adjustable and tilt angle adjustable. The keyboard support is pivotably supported on each end by two pairs of lever arms and these lever arms are all pivotably supported by a pair of slidable beams so that a parallelogram arrangement is achieved which is used for keyboard support vertical positioning. One pair of lever arms is slidably movable relative to the associated respective beams so that, by varying the distance between lever arm pivot locations along each beam, tilt positioning is accomplished. Adjustable friction enhancers permit position fixing of the lever arms when the keyboard support is in a desired attitude.

Abstract: An adjustable shelf for a refrigerator compartment has two parts, a platform and a support member and provides adjustment of both the length and the height of the shelf. The platform is attached at a first end to a compartment wall at one of two heights. The support member is slidably attached to the second end of the platform to allow adjustment of the length of the shelf. The support member has two legs with different lengths. The selection of the leg to support the platform in cooperation with selection of the corresponding attachment height at the first end of the platform determines the height of the shelf.

Abstract: A hinge assembly removably connects two bodies for pivotable movement relative to one another. The hinge assembly includes a first convex arcuate surface and a first concave arcuate surface on one body and a second convex arcuate surface and a second concave arcuate surface on the other body. The radii of curvature of the first convex arcuate surface and the second concave arcuate surface are about equal, and the radii of curvature of the second convex arcuate surface and the first concave arcuate surface are about equal, and each surface preferably defines an arc of about 180 degrees. The bodies may be assembled to one another so that the first convex arcuate surface slidingly engages the second concave arcuate surface and the first concave arcuate surface slidingly engages the second convex arcuate surface, thereby preventing relative movement of the bodies in a direction transverse to the pivot axis.

Abstract: A transaction drawer for efficiently converting the rotational motion of a carrier supporting structure into linear motion of the carrier. The carrier supporting mechanism has a first arm which is supported on a base of the drawer frame, and which pivots about the base. The first arm is pivotably connected to a second arm, which is in turn pivotably connected to the carrier. The second arm and the base are connected by a first transmission assembly, which rotates the second arm about the first arm in response to the first arm's rotation about the base. The first arm and the carrier are connected by a second transmission assembly, which rotates the carrier about the second arm in response to the second arm's rotation about the first arm. The first and second transmission assemblies cooperate to maintain the carrier at a constant angular position relative the drawer frame.

Abstract: A turntable having a bottom frame with a channel network formed on the bottom frame and a table top having a pair of guide roller attached thereon adjacent a side edge of the top. The rollers slideably engage the channels permitting the top to rotate one hundred and eighty degrees such that the top extends a minimal distance over the back edge of the bottom frame.

Abstract: A machine for applying frames to fabric in preparation for embroidering the fabric has a pair of table halves which are laterally adjustable in position to vary the spacing between them and to vary their positions relative to a frame holder. A neck piece at the front edge of each table half is also laterally adjustable relative to the table halves so as to more closely approximate the shape of a garment when it is slipped over the table. An apparatus for applying frames having an image projector and a two-bar linkage for advancing the upper frame half toward the lower frame half is also disclosed.

Abstract: A legless shelf assembly for use in a locker to provide support for articles to be stored in the locker. The shelf assembly has first and second shelf members movably relative to each other to expanded and retracted positions. Releasable cooperating rachet teeth on the side walls of the shelf members retain the shelf members in their expanded positions. An actuator cam rotatably mounted on one of the shelf members cooperates with teeth on the other of the shelf members to move the shelf members in opposite directions and further retain the shelf members in their expanded positions in tight engagement with the side walls of the locker.

Abstract: An X-Y table apparatus comprises a base (12), an X-directional moving member (14) movable in the X direction with respect to the base, a mounting member (18) movable in the Y-direction with respect to the X-directional moving member and being capable of loading articles and displacement detecting member (20) for detecting displacements of the mounting member with respect to the base. The displacement detecting member includes a main scale (24) cooperatively provided on the center of the rear face of the mounting member and having a first matrix-shaped land lattice, and an index scale (26) provided in parallel with the base so as to be movable in directions in a two-dimensional area with respect to the main scale and having a first orthogonally cross lattice (80) and a second orthogonally cross lattice (82), such that the displacement detecting member has a simple structure and effects accurate X-directional displacement and Y-directional displacement detection.

Abstract: A laterally adjustable cantilever shelf system for a refrigerator/freezer includes a formed metal bracket which defines a continuous channel. The bracket includes hooks to engage into slots in shelf standards in a refrigerated compartment. This enables the bracket to be placed at any select vertical position within the compartment. A shelf accessory includes sheet metal side arms each having a hook at the top rear that mates with a channel in the bracket to retain the shelf. Sufficient clearance is provided between the shelf side arm and the channel to allow the shelf to be moved by slightly lifting the front of the shelf to relieve the pressure between the top hook and the channel and applying lateral pressure. An additional hook at the bottom of the side arm interferes with the channel when the front of the shelf is lifted to prevent the shelf from becoming accidentally dislodged.

Abstract: A desktop mount comprises a shelf and at least two spacers for mounting said shelf on a support, e.g., on a desktop. To ensure that the desktop mount can support technical end electronic equipment which can conveniently be operated, each spacer consists of a swivel bracket, which comprises a bracket base, which is adapted to be secured to a desktop or other support, and a bracket arm, which is pirated to the bracket base and to the shelf on spaced apart vertical axes.

Abstract: First and second sliding bodies are guided along a first axis on linear guide rails. A linkage connects a table to the first and second sliding bodies. The linkage moves the table parallel to the linear guide rails when the first and second sliding bodies are displaced the same distance. The linkage moves the table perpendicular to the linear guide rails when one of the sliding bodies is moved a different distance from the first sliding body. The perpendicular distance can be either the Z axis or the Y axis.

Abstract: A drive system comprises a pair of racks provided in a first direction, a pair of travellers, each of which is capable of moving in the first direction alongside each rack, a connecting member provided in a second direction perpendicular to the first direction, each end of the connecting member is fixed to each traveller, a pair of pinions, each of which engages with each rack and rolls thereon in the first direction, the pinions coaxially connected by a shaft, and a first motor for driving at least one of the travellers in the first direction, wherein the first motor is not mounted on the travellers and the connecting member. With this structure, the movable parts of the drive system are lightened so that high speed operation is made possible.

Abstract: A drive apparatus and a XY drive apparatus on which it is equipped that accomplishes highly accurate driving and positioning of a driven object by absorbing deflection of a nut in the radial direction while employing a simple construction.Deflection of a nut is absorbed by deflection of flexible portions as a result of said nut being supported by an intermediate member having said flexible portions able to deflect in a radial direction perpendicular to the shaft center of a feed screw.

Abstract: A moving base is provided relative to a stage base fixed to a microscope's body and is movable in a linear direction with a specimen placed thereon. A drive wheel coaxial with an operation handle is mounted on the stage base such that it is rotatable. A rail is mounted relative to a mount face of a moving base with an elastic member therebetween such that it is fixed at both ends. The rail is placed in pressure contact with a V groove of the drive wheel by an elastic force of the elastic member. Even if there occur warping of the rail and eccentric state of the drive wheel, the elastic member is correspondingly deformed elastically so that the state of contact of the rail with the drive wheel is uniformly controlled by an elastic force of the drive wheel.

Abstract: An X-Y drive apparatus suitable for use in positioning an electronic component or the like at a desired position, such as a mounting position of a printed circuit board, is provided. Each of X and Y table units includes an elongated housing provided with a pair of stationary pulleys at its opposite ends and a table provided with a pair of moving pulleys. A pair of brackets is also mounted on the housing, each located between one of the stationary pulleys and a corresponding one of the moving pulleys. A belt, having its one end fixedly attached to one of the brackets, extends first around one of the moving pulleys, then around each of the stationary pulleys, and then around the remaining moving pulleys with its remaining end fixedly attached to the remaining bracket.

Abstract: This invention describes a computer workstation which places the monitor below and behind the keyboard. The shelf for holding the monitor is rotatable independently of movement of a shelf for holding the keyboard. A plurality of shelves are also provided for additional equipment and supplies. In one embodiment, the workstation has separate paper supply and used paper holding shelves. In another embodiment, these shelves are combined.

Abstract: A movable table has a fixed platen, a movable platen, a plurality of balls for supporting the movable platen over the fixed platen, a retainer provided between the fixed platen and the movable platen for retaining the balls, and a restrictor for restricting the movement of the retainer. The movable platen is moved in one direction by at least two first driving assemblies and is moved in a direction perpendicular to the above direction by a second driving assembly. The first and second driving assemblies are coupled to the movable platen so as to be pivotable and slidable in a direction perpendicular to the direction in which is moves the movable platen.

Abstract: A mechanism for moving a table structure having a table as a part thereof in the lengthwise and crosswise direction and turning movement of the table, the mechanism having a support base, support bearing structure on the support base for supporting the table structure for movement in the lengthwise and crosswise direction and turning movement of the table, two mutually orthogonal pairs of parallel guide faces adapted to be mounted on the table structure, guide members on opposite sides of the table structure and engaged with the guide faces for controlling the movement of the table structure in the lengthwise and crosswise direction and turning movement of the table, and a moving device connected to at least some of the guide members for moving appropriate ones of the guide members for causing movement of the table structure along the other of the guide members in the lengthwise and crosswise direction of the table and in turning movement of the table.

Abstract: A keyboard support assembly for a computer work stand is disclosed comprising a subplate (74) having a profiled opening (98, 100) along each side, and a keyboard support plate (78) residing on top of the subplate. A pair of pivotal locking devices (138) are attached to the underside of the keyboard support plate to depend into the subplate profiled openings, and to selectively engage against an underside of the subplate as the keyboard support plate is slideably re-positioned thereon. The locking devices (138) include gear teeth 140 which engage with a gear rack segment 102 along the subplate underside.

Abstract: A slidable loading platform for a vehicle comprising a bed slidably mounted atop a truck array. A plurality of roller assemblies associated with the track and with the bed enhances a slidable movement of the platform relative to the track array. A locking mechanism precludes undesirable shifting of the bed during vehicle transport and unloading.

Abstract: A slidable loading platform for a vehicle comprising a bed slidably mounted atop a track array. A plurality of roller assemblies associated with the track and with the bed enhances a slidable movement of the platform relative to the track array. A locking mechanism precludes undesirable shifting of the bed during vehicle transport and unloading.

Abstract: The present disclosure describes a portable bench which finds particular application in the automotive field. The bench is comprised of a main body for supporting a pair of opposed drawers in sliding relationship to one another. When the drawers are in a closed position, they are concealed within the main body. A support assembly is removably attached to the front of each of the drawers. In use, the bench is oriented at a right angle to the longitudinal axis of the vehicle. The drawers are slid outward from the main body to permit the support assemblies to engage the respective opposite fenders of the vehicle. Tools, parts and related materials may be rested upon the main body which can be slid from one extremity of the bench to the other. Items placed in the drawers during use of the bench may be temporarily stored therein when the bench is removed from the vehicle and the drawers closed.

Abstract: A rolling bench for storing plants in greenhouses and other applications. The rolling bench has a platform stop supported on a base for edgewise movement beyond opposite sides of and restrained against tilting relative to the base by means of an improved roller glide system. This improved roller glide system has parallel rollers disposed between and in rolling contact with the base and top and spacers for retaining the rollers in spaced relation, such that during edgewise adjustment of the top, the rollers undergo rolling movement relative to the base and top along the direction line of movement of the top with the rollers retained in proper spaced relation to rollably support the top throughout a full range of movement.

Abstract: An apparatus for locking a movable stage onto a stationary base, the stage being moved in the state floating above the base. The apparatus comprises a cap-like vacuum suction plate fixedly combined with the stage and defining a space in cooperation with the stationary base, wherein the space is selectively connected either to an air supply source or to a vacuum source. To move the stage in the floating stage, the space defined below the vacuum suction plate is connected to the air supply source to thereby form an air bearing between the vacuum suction plate and the base plate, whereby a gap and parallelism is maintained therebetween. Upon completion of positioning of the stage, the space is connected to the vacuum source so that the vacuum suction plate is locked onto the stationary base under the suction effect brought about by evacuation of the space.

Abstract: A table for use in a hot cell or similar controlled environment for use in examining specimens. The table has a movable table top that can be moved relative to a table frame. A shaft is fixedly mounted to the frame for axial rotation. A shaft traveler having a plurality of tilted rollers biased against the shaft is connected to the table top such that rotation of the shaft causes the shaft traveler to roll along the shaft. An electromagnetic drive is connected to the shaft and the frame for controllably rotating the shaft.