Abstract: A robotic surgical tool includes an elongate shaft extended through a handle and having an end effector arranged at a distal end thereof, a rack extending along a portion of the shaft and operatively coupled to a knife located at the end effector, a first actuation system housed within the handle and operable to drive the rack and thereby advance or retract the knife at the end effector, the first actuation system including a sector gear engageable with the rack and including a tooth-free zone, and a second actuation system housed within the handle and operable to cause z-axis translation of the shaft through the handle. Rotating the sector gear such that the tooth-free zone faces the rack decouples the shaft from the first actuation system to allow the shaft to freely move in z-axis translation.

Abstract: The invention relates to a safety brake for an elevator, a centrifugal regulator and a way of using this in a safety brake. According to the invention, the safety brake comprises a centrifugal regulator (3), a shaft (4), which rotates due to a coupling (5) to the elevator, a first (6) and a second (8) brake part movable against each other with friction surfaces (10, 11), the first brake part being rotatable with the shaft, a spring assembly (30) with which the brake parts are spring-biased with a pressure force, on release the centrifugal regulator is provided to couple the shaft (4) to the first brake part (6) to force rotation on it.

Abstract: An illustrative example elevator assembly includes a header beam and a first elevator cab supported by the header beam. A plurality of vertically oriented rods extend beneath the first elevator cab. A horizontally oriented mid-beam is coupled to a first one of the rods near a first end of the mid-beam and coupled to a second one of the rods near a second end of the mid-beam. A second elevator cab is situated beneath the first elevator cab and beneath the mid-beam. At least one linear actuator is supported at least partially on the mid-beam. The linear actuator selectively causes vertical movement of the second elevator cab relative to the rods.

Abstract: This invention provides a rack apparatus, a delivery carriage and the automated storage and distribution system thereof. In the rack apparatus, there are only two racks at both sides of the rack apparatus extending in a generally vertical direction. And in the carriage, there are only two driving wheels. Therefore, both the rack apparatus and the carriage simplify the structure of the rack apparatus and the carriage and reduce the installation accuracy and the failure points thereof, but still provide new improvements to keep the carriage body horizontal with the ground.

Abstract: An illustrative example elevator assembly includes a header beam and a first elevator cab supported by the header beam. A plurality of vertically oriented rods extend beneath the first elevator cab. A horizontally oriented mid-beam is coupled to a first one of the rods near a first end of the mid-beam and coupled to a second one of the rods near a second end of the mid-beam. A second elevator cab is situated beneath the first elevator cab and beneath the mid-beam. At least one linear actuator is supported at least partially on the mid-beam. The linear actuator selectively causes vertical movement of the second elevator cab relative to the rods.

Abstract: A storage system features a fleet of storage/retrieval vehicles and a gridded three-dimensional structure. The structure features a gridded two-dimensional track layout on which the one or more storage/retrieval vehicles are conveyable in two directions, and a plurality of storage columns residing above or below the gridded track layout in spaced distribution throughout the two-dimensional area of the track layout. Upright shafts reside above or below the gridded track layout and provide vehicle access to the storage columns. At least one working station resides outside the two-dimensional area of the track layout, and via one or more extension tracks, is served by the same vehicles that navigate the gridded structure.

Abstract: An elevator system may include at least two elevator shafts and at least one elevator car. A vertically extending rail may be disposed in each elevator shaft, and the elevator car may travel along the vertically extending rail. Each rail may be formed with a rotatable segment such that the rotatable segments can be aligned relative to one another in a transfer plane. Thereafter, the elevator car may travel between the elevator shafts along the segments. In some cases, the vertically extending rail may form part of a linear drive that causes the elevator car to move without the use of cables.

Abstract: An elevator system may include at least two elevator shafts along with an elevator car with a cab and a chassis device. The cab may be mounted rotatably about a horizontal rotational axis relative to the chassis device. A vertically extending rail, along which the elevator car is movable, may be disposed in each elevator shaft. Each of the rails may include a rotatable segment such that the rotatable segments are alignable with respect to one another so that the elevator car is movable along the segments between the elevator shafts. A first device may lock the cab relative to the chassis device, and a second device may hold the cab relative to the elevator shafts.

Abstract: In one embodiment, an inventory storage module has first and second guiderails that are spaced from one another along a lateral direction. Each guiderail has an upper track and a lower track, and first and second connecting tracks that connect the upper track to the lower track at first and second ends of the storage module, respectively. The module has a plurality of inventory carriers that are supported between the first and second guiderails, are arranged end-to-end along the upper and lower tracks along a longitudinal direction, and are elongate along the lateral direction. The module can also have a plurality of storage containers carried by each inventory carrier in a side-by-side relation along the lateral direction, where the plurality of storage containers carry a plurality of inventory items.

Abstract: An elevator system may include at least two elevator shafts and at least one elevator car. A vertically extending rail may be disposed in each elevator shaft, and the elevator car may travel along the vertically extending rail. Each rail may be formed with a rotatable segment such that the rotatable segments can be aligned relative to one another in a transfer plane. Thereafter, the elevator car may travel between the elevator shafts along the segments. In some cases, the vertically extending rail may form part of a linear drive that causes the elevator car to move without the use of cables.

Abstract: An elevator system that may be ropeless is in a structure and includes a guide rail and a guide rail extension that may generally guide a car between a hoistway and a transfer station of the system. The rail extension may generally project telescopically downward from the first rail and toward the transfer station. The telescopic relationship between the guide rail extension and the guide rail may generally compensate for vertical structure compression that may occur over a period of time.

Abstract: Some embodiments include a track system comprising: an elevated track system comprising a series of elevated tracks that are positioned elevated above a sales floor and products distributed over at least a portion of the sales floor of a shopping facility, and configured such that multiple motorized transport units travel along the series of elevated tracks in traversing at least portions of the shopping facility.

Abstract: An elevator system includes a first hoistway; a second hoistway; and a structural member disposed between the first hoistway and the second hoistway; the structural member supporting a first stationary portion of a propulsion system for the first hoistway; the structural member supporting a first guide surface for an elevator car in the first hoistway; the structural member supporting a second stationary portion of the propulsion system for the second hoistway; the structural member supporting a second guide surface for an elevator car in the second hoistway.

Abstract: An inter-floor transport facility in which a raising and lowering transport device is provided for each of the raising and lowering paths that are adjacent to each other. Receiving platforms include a carry in article receiving platform for supporting an article that is being carried in to the floor, a carry out article receiving platform for supporting an article that is being carried out from the floor, and a storage-purpose receiving platform for storing a transported article. On each floor, the carry in article receiving platform and the carry out article receiving platform are so located that the article can be transferred between one transfer device and both of the carry in article receiving platform and the carry out article receiving platform, and the storage-purpose receiving platform is so located that all of the transfer devices can transfer the article to or from the storage-purpose receiving platform.

Abstract: A transport mechanism for transporting a travel body that can self travel and includes: a motor; a drive wheel to which rotary torque of the motor is transmitted; and a first gear to which the rotary torque of the motor is transmitted is provided. The transport mechanism includes: a transport body configured on which the travel body is placed for transportation, the transport body including a second gear that can mesh with the first gear of the placed travel body; a movement mechanism for moving the transport body, on which the travel body is placed, by the rotary torque of the motor transmitted to the second gear; and an idling section for causing an idle state in which the drive wheel rotates idle in a state where the first gear and the second gear mesh with each other and rotation of the second gear is permitted.

Abstract: An elevator arrangement includes two or more hoistways, at least one more elevator car than a total number of hoistways, and at least one more belt system than the total number of hoistways. At least one belt system may be provided between each pair of hoistways. At least one elevator car may be provided in each hoistway. Each elevator car may be connected to at least one belt system. The belt systems may provide a direct transfer of mechanical energy between the elevator cars. As a first elevator car moves downward in a first hoistway, mechanical energy may be generated via the belt systems to lift a second elevator car upwardly in a second hoistway.

Abstract: Described is a lift unit for ascending and descending in a shaft formed by a scaffold column of a scaffold, the scaffold column comprising at least one scaffold section, each scaffold section being defined by uprights and ledgers, comprising a first part adapted to be fixed at different heights to the scaffold by means of a first set of fixing means; a second part adapted so that it can be fixed at different heights to the scaffold by means of a second set of fixing means; a distance control means adapted to drive a variation in the distance between the first set of fixing means and the second set of fixing means; and methods for use of the lift unit.

Abstract: An elevator has a car movable within a hoistway, a rack extending along the hoistway, the rack having a toothed profile with wave troughs and wave crests and a drive mounted in proximity to the rack so that the drive interacts with the rack to move the car. The drive includes a roller pinion unit fixedly mounted on a shaft and having a predetermined number of roller pinions arranged in a circle around the shaft and extending parallel to the shaft. The roller pinion unit interacts with the toothed profile of the rack. The drive also includes a motor unit configured to rotate the shaft. Optionally, the drive includes a brake unit configured to act on the shaft.

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 lift assembly installable on a vehicle. The lift assembly includes a support structure securable to the vehicle, a pair of parallel vertically extending geared tracks and a vertically moveable drive assembly. The drive assembly includes (a) a mounting structure; (b) a selectively reversible motor; (c) a pair of gears; and (d) a moveable first tread. The gears are engaged with the tracks and rotatably supported on the mounting structure. The gears are also drivingly coupled with the motor wherein operation of the motor selectively raises and lowers the mounting structure relative to the support structure. The moveable first tread is secured to the mounting structure and is adapted to support an operator whereby raising and lowering the mounting structure raises and lowers an operator positioned on the first tread. In some embodiments, the lift assembly includes water-resistant foot-operable switches to control the raising and lowering of the mounting structure.

Abstract: An elevator has a car movable within a hoistway, a rack extending along the hoistway, the rack having a toothed profile with wave troughs and wave crests and a drive mounted in proximity to the rack so that the drive interacts with the rack to move the car. The drive includes a roller pinion unit fixedly mounted on a shaft and having a predetermined number of roller pinions arranged in a circle around the shaft and extending parallel to the shaft. The roller pinion unit interacts with the toothed profile of the rack. The drive also includes a motor unit configured to rotate the shaft. Optionally, the drive includes a brake unit configured to act on the shaft.

Abstract: A lift assembly installable on a vehicle. The lift assembly includes a support structure securable to the vehicle, a pair of parallel vertically extending geared tracks and a vertically moveable drive assembly. The drive assembly includes (a) a mounting structure; (b) a selectively reversible motor; (c) a pair of gears; and (d) a moveable first tread. The gears are engaged with the tracks and rotatably supported on the mounting structure. The gears are also drivingly coupled with the motor wherein operation of the motor selectively raises and lowers the mounting structure relative to the support structure. The moveable first tread is secured to the mounting structure and is adapted to support an operator whereby raising and lowering the mounting structure raises and lowers an operator positioned on the first tread. In some embodiments, the lift assembly includes water-resistant foot-operable switches to control the raising and lowering of the mounting structure.

Abstract: The elevator safety rescue system is an electro-hydraulic system particularly suited for use in rack and pinion drive elevators installed with tall towers, mines, smoke stacks, and other structures having relatively large elevations or depths. The system includes a positive displacement hydraulic pump driven by the output shaft of an electric elevator drive motor. An electro-hydraulic valve is electrically powered to maintain an open condition to allow unrestricted hydraulic flow through the pump during normal operation. In the event of an elevator malfunction, electrical power is terminated to the valve, causing the valve to close and thus requiring all hydraulic fluid to pass through a restrictor. The restrictor limits the flow of hydraulic fluid through the hydraulic pump, thus limiting its rotational speed and rotational speed of the elevator drive motor to which it is attached, thereby allowing the elevator to descend or climb (with counterweight) at a safe speed.

Abstract: A portable elevator climbing system removably attachable to a cantilevered overhang on an adjacent structure, whereby an elevator car travels up and down a plurality of roller chains. The roller chains are engaged with sprockets and guide rollers attached to an axle driven by a motor. The orientation and alignment of the sprockets, guide rollers and roller chains provide for a stable elevator car and for a system free of backlash in both directions. The elevator climbing system includes a dampening assembly to control the rate of decent in the event of transmission, motor or other failure. The elevator climbing system may be controlled so that the start and stop of the motor is coordinated with the release and application of a braking assembly. The efficiency of the elevator climbing system may be varied by adjusting the offset between the sprockets and the guide rollers.

Abstract: The invention relates to a lifting assembly (10, 20, 30, 40, 50, 60, 70, 80, 90) comprising: a rack mast, a platform (12, 23, 33, 43, 53, 91), and at least one power unit (100, 300, 400, 500, 600, 800, 900, 901) which is mounted to the mast and which controls the vertical movement of the platform along the length thereof. The invention is characterized in that the power unit comprises a plurality of modular elements including at least one motor block (101, 200, 201, 301, 401, 501, 604, 621, 801, 904), at least one upper roller box (102, 205, 210, 305, 404, 503, 627, 903) and at least one lower roller box (103, 206, 304, 405, 502, 601, 629, 902). According to the invention, each of the modular elements is equipped with mechanical fastening means (610, 611, 612) which are aligned with the mechanical fastening means of an adjacent modular element.

Abstract: We have described a modular lift with a motorised cabin on a mast with a simpler, more comfortable and faster assembly with safer use than conventional mechanisms of the same type. The modular lift is made up of a carrying element or mast into which the rack has been incorporated and is formed by multiple successive modules screwed at the adjoining ends which allow it to be built to the required height, with the modules anchored via bracings. The moving parts are made up of the cabin constructed based on a parallelepiped mast that incorporates the rolling and guiding parts of the lift, the traction groups, the parachute brake, the suspension and the button control panel. Upper and lower guiding rollers are placed on the inclined sides at the rear with respect to the back wall of the cabin and attack pinions in relation to engagement with the rack.

Abstract: The invention concerns an arrangement for securing a lift car (1) that is part of an electrically driven lift at a predetermined level for, for example, service or maintenance, and for preventing unintentional motion of the lift car secured in this manner, whereby the lift car may be of the type that is arranged with a cage or platform for the transport of persons or material.

Abstract: The invention provides for a transport system and method of using the transport system. The transport system may include a transport track; and a platform assembly that transports along the transport track, the platform assembly including (1) a cargo platform; and (2) a pair of drive pinion trucks mounted on opposing sides of the cargo platform, each drive pinion truck engaged with the transport track for movement along the transport track. The drive pinion trucks may be provided with a leveling system to provide leveling of the cargo platform during operation.

Abstract: The invention provides for a transport system and method of using the transport system. The transport system may include a transport track; and a platform assembly that transports along the transport track, the platform assembly including (1) a cargo platform; and (2) a pair of drive pinion trucks mounted on opposing sides of the cargo platform, each drive pinion truck engaged with the transport track for movement along the transport track. The drive pinion trucks may be provided with a leveling system to provide leveling of the cargo platform during operation.

Abstract: An automated storage and retrieval system wherein electrically driven, computer-controlled carriages (58) can navigate a system of rails (78) in three-dimensions. Multiple carriages (58) can independently operate at the same time to accomplish a task faster or to work on several different tasks at the same time. The rails (78) have a system of trap doors (95) that allow a carriage (58) to use a single reversible motor (67) to navigate the rails (78) in three-dimensions. With the carriage (58) in positioned in font of a bin position, the carriage mounted manipulating device (125) can move bins (115) to and from the racks (107) from either side with a single reversible motor (131). The rails (78) are electrified to provide power for the drive (67) and manipulator motors (131). A main computer (146) maintains the inventory, handles transactions and assigns tasks to the computer-controlled carriages (58).

Abstract: A lift drive comprising: a spiral drive element having an axis of rotation, a rack having teeth sized and shaped to be engaged by the spiral drive element, the rack having a longitudinal axis parallel to the axis of rotation, and a motor to rotate the spiral drive element, wherein upon the spiral drive element-rotating, one of the spiral drive element and the rack moves relative to the other along the longitudinal axis.

Abstract: A dampening device for use with elevator cars or similar devices prevents damage to objects or persons within the elevator car upon failure of a drive chain. A hydraulic motor regulates the rate of descent. The dampening motor is monitored constantly using a pressure gauge.

Abstract: To provide a compact lifter device, which can attain a work-piece's lifting/lowering operation in a stable supporting state and can reduce the parts number and an assembly load.

Abstract: An elevator mechanism protects the control, communications, power, and/or lift cable(s) of the elevator system, precluding lateral cable movement within the elevator shaft. A slotted cable guide contains a cable therein, with the cable having a diameter larger than the guide slot to preclude escape of the cable from the guide. The upper end of the cable has a reduced diameter and extends through the guide slot, where it is supported by a lift bar extending from the elevator car and into the slot. A mechanism allows the lift bar to move laterally to preclude binding in the guide if the elevator car shifts laterally slightly. Another mechanism shuts down the system if the cable and/or cable reel jams. The present elevator mechanism is adaptable to virtually any type of elevator and lift mechanism, but is particularly useful with elevators used in tall, open structures.

Abstract: A mechanical system and method for constructing a self-supporting, elevator support structure and a traction (rope-operated) elevator system comprising such a support structure. A rail-climbing platform is used to progressively erect higher levels of modular rail sections and other components of the system without the need for external props such as a scaffold.

Abstract: A spiral propeller provides a better secure and a more reliable spiral comprising spiral-lifting wheels, interlocking wheel interlocked with the spiral-lifting wheel, and fixed track supporting the interlocking wheel; the spiral lifting wheel is a rotating wheel with spiral external teeth, which is fixed at the top of the compartment, so as to drive the compartment for upward and downward movements, and interlock with the interlocking wheel; a interlocking rotating wheel of truncated cone shape, which can rotate along the axial direction of the wheel itself; a fixing track is set up between the guide brackets of the elevator, i.e., between the vertical supporting brackets of the guide bracket, in the appropriate locations are set with interlocking wheels.

Abstract: A staircase guide for a device for ascending a staircase, the device has a frame with a carrying element for people or goods and a drive connected to the frame. The guide has a cylindrical tube to be adapted to a staircase with at least one protrusion which extends in longitudinal direction of the tube. The tube has an engaging surface for co-action with a drive element of the drive for the purpose of displacing the stairlift and a support surface for support of the drive by a support member in order to hold at least the carrying element upright.

Abstract: An elevating platform assembly includes a generally vertical mast having a generally vertical rack mounted thereon. A first trolley is coupled to the mast and is moveable therealong. A drive mechanism is carried by the first trolley and includes at least one pinion in mating engagement with the rack. An elongated elevating platform extends from the mast and has a second trolley mounted adjacent one end thereof. The second trolley couples the elevating platform to the mast and is moveable along the mast. The first trolley is coupled to at least one of the second trolley and elevating platform in a manner to maintain alignment of the at least one pinion and rack when loads are placed on the elevating platform that create moments at the mast.

Abstract: An emergency moving device of an elevator includes a main moving gear and a reduction gear, both disposed on the top of the elevator car. Chains are passed under a respective one of several gears connected to shafts of the reduction gear. The chains are connected to a first connector, which is disposed above the car, and is connected to steel ropes of the car. When a breakdown of the elevator causes the car to stop between two of the floors, the passengers can control an emergency power supply to activate. A fall prevention member to free the carriage from the first connector for permitting the carriage to move down relative to the first connector; the emergency power also activates a braking switch of the main gear for same to turn in order to drive the reduction gear and the gears connected to the chains for lowering the car.

Abstract: An elevating platform assembly includes a generally vertical mast having a generally vertical rack mounted thereon. A first trolley is coupled to the mast and is moveable therealong. A drive mechanism is carried by the first trolley and includes at least one pinion in mating engagement with the rack. An elongated elevating platform extends from the mast and has a second trolley mounted adjacent one end thereof. The second trolley couples the elevating platform to the mast and is moveable along the mast. The first trolley is coupled to at least one of the second trolley and elevating platform in a manner to maintain alignment of the at least one pinion and rack when loads are placed on the elevating platform that create moments at the mast.

Abstract: A drive configuration for stair lifts is described. The drive configuration has a load-bearing configuration which is mounted displaceably on a first (bottom) guide rail and a second (top) guide rail. A drive unit interacts with a drive rail. The drive rail is formed by a perforated bar which has engagement openings spaced apart at regular intervals in the longitudinal direction and also has two uninterrupted, mutually opposite running surfaces. The drive unit has two gearwheel-shaped drive wheels which are disposed opposite one another, and accommodate the perforated bar with a radial contact-pressure force between them. The drive wheels have drive surfaces which are uninterrupted in the circumferential direction and radially projecting drive protrusions, the drive protrusions interacting with the engagement openings in a form-fitting drive connection and the drive surfaces interacting with the running surfaces in a force-fitting drive connection.

Abstract: A linear actuator includes an inner section that moves within an outer section. The inside of the outer section includes racks and the outside of the inner section includes pinions that engage the racks. Two pairs of racks and pinions are positioned at an angle of 90° with respect to each other. The outer section includes at least two pairs of sides located opposite to one another and one of the racks is mounted on each of the sides.

Abstract: In a chair type stair elevating device in which upper and lower rails and a rack or chain parallel to the rails are provided along the stairs, an elevating mechanism mounted on the rails is moved by a pinion or sprocket of a driving machine meshing with the rack or chain. A chair is mounted on the elevating mechanism, and the rack or chain is received in the rail in a hidden state. In this way, the rack or chain is invisible, so that the design value of the entire device improves, and it is also possible to prevent injury and soiling of clothes by the rack or chain.

Abstract: An elevator system control box is mounted on an elevator car above or below a car door. The mounting position of the control box makes it possible for a service technician to reach elevator drive system components, such as a travel regulation unit, safety circuits, an optional drive regulation unit, a frequency inverter, etc., mounted in the control box conveniently standing at hand or eye level at a floor with the shaft doors opened.

Abstract: An elevator cab includes an indentation in the shape of the cab. The indentation permits the cab to be compact without compromising the floor area of the cab. In a particular embodiment, the indentation accommodates the presence of a machine in the hoistway when the cab is adjacent to the machine.

Abstract: A safety device for vertically moving load carrier is disclosed. It includes a vertical column, a retainer, a vertical safety rack, a pivot shaft, a safety detent pivotally fitted on the pivot shaft and a resilient member. When a flexible transmission belt disposed in the vertical column is in a normally sealedly installed state, the safety detent is positioned in a first position without contacting with the safety rack. While in case the transmission belt is accidentally broken and in a loosened state, the safety detent is forced by the resilient member and rotated to a second position in contact with the safety rack. In the second position, the engaging section of the safety detent is just engaged with a horizontal section of one tooth of the safety rack so that the retainer and the load carried thereby are kept stationary at a certain height without abruptly dropping down to cause accident.

Abstract: A traction drive elevator system preferably comprises a pair of vertical tracks, a car, and at least one counterweight for supporting at least a portion of the weight of the car. A traction drive, which preferably includes a frame which is separate from the car, comprises two sets of drives, each including a large traction roller and a pair of smaller diameter counter rollers which are disposed on opposite sides of one of the tracks. The axis of the traction roller is horizontal preferably at a height midway between the axes of the counter rollers, and the counter rollers are moveable in a direction toward the track. Means, preferably an eccentric mounting in combination with a gas spring, urge the counter rollers towards the track, thereby creating friction between the rollers and the track. A motor and gear box, which preferably includes a worm and spur gear combination, selectively rotate the traction rollers for moving the car between landings.

Abstract: In accordance with one embodiment of the present invention, the mobile lift system includes a 3 ft..times.3 ft. rack and pinion platform lift providing a cage able to lift at least one man and gear up a pole of a billboard sign or any advertising sign and to detach the platform from the rack so access can be achieved at many different pole/rack sites with a single platform lift. The mobile hoist or lift is practical because it eliminates ladders from tall poles and provides safer route access. This will save time for the worker because his harness has been eliminated and the hardship of climbing the ladders has also been eliminated. Another point of interest will be the saved money and reduced liability because the ladders have been removed so that unauthorized individuals cannot climb up the poles. Mobilizing the lift saves money in material cost and maintenance because there may be one platform for 150 racks (poles) or more.

Abstract: A lift drive comprising: a spiral drive element having an axis of rotation, a rack having teeth sized and shaped to be engaged by the spiral drive element, the rack having a longitudinal axis parallel to the axis of rotation, and a motor to rotate the spiral drive element, wherein upon the spiral drive element-rotating, one of the spiral drive element and the rack moves relative to the other along the longitudinal axis.