Lift assembly, system, and method

A lift assembly system and method can include a substantially rectangular tube, a motor operably connected to first and second traction drives and a rotatable drum and structurally connected to one end of the tube, a head block fixed to the opposite end of the tube, and a plurality of loft blocks positionable at an infinite number of locations within the tube. An elongate member attached on one end to the drum can be routed through a generally horizontal path from the drum to the first and second traction drives, the head block, and the loft blocks, and then through a generally vertical path from the loft block to an attached article. The elongate member can be wound about the drum to raise the article, and unwound from the drum to lower the article. The system can further include a load-side braking mechanism. The tube can include a compressible material adapted to absorb at least a portion of a horizontal load placed on the lift system.

FIELD OF THE INVENTION

The present invention relates to a lift assembly, system, and method. Embodiments of the present invention may be useful for raising and lowering a load in theatrical and staging environments.

BACKGROUND OF THE INVENTION

Performance venues such as theaters, arenas, concert halls, auditoriums, schools, clubs, convention centers, and television studios can employ battens or trusses to suspend, elevate, and/or lower lighting, scenery, draperies, and other equipment that can be moved relative to a stage or floor. Such battens can include pipe or joined pipe sections that form a desired length of the batten. Battens can be 50 feet or more in length. To support heavy loads or suspension points are that spaced apart, for example, 15-30 feet apart, the battens may be fabricated in various configurations, such as ladder, triangular, or box truss configurations. A number of elevating or hoisting systems are available for supporting, raising, and lowering battens and/or articles used in such venues.

Battens can be counterweighted in order to reduce the effective weight of the battens and any associated loads. As a result, the power necessary to raise and lower battens can be reduced. However, conventional counterweight systems can represent a significant cost, with respect to both equipment required and time involved to install such equipment.

Some conventional elevating or hoisting systems can employ a winch to raise and/or lower battens and other articles. Such winches can be hand-operated, motorized, and/or electrically powered. Other conventional elevating or hoisting systems can utilize a hydraulic or pneumatic device to raise and/or lower battens.

Conventional elevating or hoisting systems can include a locking device and an overload limiting device. In a sandbag counterweight system, for example, the locking device may be merely a rope tied off to a stage-mounted pin rail. The overload limit can be regulated by the size of the sandbag. In such a rigging design, however, a number of additional bags can be added to the set of rope lines, and thereby exceed the safe limit of suspension ropes and defeat the overload-limiting feature.

Elevating or hoisting systems that utilize winches can employ a locking mechanism, such as a ratchet lock mechanism. When such winches are heavily loaded, the locking capacity of the ratchet lock, or other locking mechanism, can be overcome, resulting in the suspended load being dangerously dropped. As a result, conventional lift systems can have less than effective safety mechanisms.

In addition, conventional lift systems may be configured such that a loft block, or pulley, mechanism is attached directly to an overhead building support. As a result, an undesired amount of horizontal stress can be placed on the overhead building supports to which the system and associated load are attached.

Thus, there is a need for a lift assembly that can replace traditional counterweight systems. There is a need for a lift assembly that provides effective safety mechanisms. There is a need for a lift assembly that reduces undesired horizontal stress on building supports.

SUMMARY

Some embodiments of a lift assembly and system of the present invention can include a tube, a drum, an elongate member, a drive mechanism, a head block, and a loft block. The tube can be a substantially rectangular tube having an opening in a bottom along at least a portion of the length of the tube. The tube can be connectable to an overhead structure. The drum can be located external to the tube and adapted to wind and unwind the elongate member to raise and lower an article attached to the elongate member. The drive mechanism can be structurally connected to one end of the tube externally. The drive mechanism can include a motor rotatingly connected to a first traction drive and operably connected to the drum and to a second traction drive, such that the elongate member extends along a first generally horizontal path from the drum about the first and second traction drives to the tube. The head block can be fixedly connected to an opposite end of the tube and located to redirect the elongate member from the first generally horizontal path to a second generally horizontal path back toward the drive mechanism. The loft block can be connected to the tube internally, spaced from the head block, and located to redirect the elongate member from the second generally horizontal path to a generally vertical path through the bottom opening in the tube to the attached article.

In some embodiments, the lift assembly and system can include a plurality of the loft blocks. Each loft block can be positionable and securable in place at an infinite number of locations along the length of the tube. In some embodiments, the lift assembly and system can include a braking mechanism connected to the elongate member and movable within the tube. In some embodiments, the tube can further comprise a substantially rigid, compressible material adapted to absorb at least a portion of a horizontal load placed on the lift system between the drive mechanism and the loft block. Certain embodiments of the lift assembly and system can include a plurality of the tube modules arranged in an end-to-end configuration.

Some embodiments of the present invention can include a method for raising and lowering an article utilizing embodiments of the lift assembly and system described herein. Such a method can include, for example, connecting the tube to an overhead structure, attaching an end of the elongate member to an article, winding the elongate member about the drum to raise the article, and unwinding the elongate member from the drum to lower the article.

DETAILED DESCRIPTION

Some embodiments of the present invention can provide a lift assembly, system, and/or method.FIGS. 1-13show various aspects of such embodiments. An illustrative embodiment of a lift assembly system10can include a coiling apparatus, or drum25, a first traction drive26operably connected to a drive mechanism23, a second traction drive27, a tube11containing one or more pulleys, for example, a head block39and loft blocks32, and one or more elongate members31, such as cables. The cables31can be attached to the drum25and configured to travel in a generally horizontal path from the drum25around the second traction drive27to and around the first traction drive26to the head block39and the loft blocks32inside the tube11. From the loft blocks32, the cables31can travel in a generally vertical path, that is, upward and downward between the loft blocks32and a surface below. An article22, or load, can be attached to the cables31such that when the cables31are moved in the generally vertical path, the attached article22can be raised and/or lowered relative to the surface.

Such embodiments of a lift assembly, system, and/or method may be useful for raising and/or lowering articles22, such as theatrical stage equipment, relative to a stage floor. Theatrical stage equipment can include equipment which is to be raised and/or lowered prior to and/or during a performance, in order to provide a desired scene effect. This equipment can include, for example, various rigging sets such as curtains, borders, screens, scene displays, props, lighting fixtures, and other equipment. The rigging sets, some of which can be generally coextensive in length with the opening of a theater stage, can have substantial mass and weight. Some embodiments of a lift assembly, system, and/or method of the present invention may be used for raising and/or lowering articles22and loads other than theatrical stage equipment.

In certain instances, the articles22to be raised and lowered can be stage equipment supported by one or more battens. A “batten” can comprise an elongated pipe, rod, or rigid strip of material. Each batten can be supported along its length by a plurality of flexible cables. Although the term “batten” is used in connection with theatrical and staging environment, including scenery, staging, lighting and sound equipment, etc., the term can encompass any load connectable to an elongate member31, such as a windable cable.

Some embodiments of a lift assembly, system, and method of the present invention can be utilized in connection with buildings in various settings. The term “building” as used herein can encompass a structure or facility to which the lift assembly10is connected, such as, but not limited to, performance venues, theaters, arenas, concert halls, auditoriums, schools, clubs, educational institutions, stages, convention centers, television studios, showrooms, places of religious gathering, cruise ships, etc.

In some embodiments of the present invention, the lift assembly system10can include a coiling apparatus, or drum25, as shown inFIGS. 2-4. One end of the elongate members31, or cables, can be securely attached to the drum25. The drum25can include a series of channels59or contoured surface areas about which the cables31can be coiled, or wound, and from which the cables31can be uncoiled, or unwound. In some embodiments, the drum25can include a channel59or contoured surface area for each cable31to be wound and unwound. For example, as shown inFIGS. 3 and 11, the drum25can include eight cable-receiving channels59. Each channel59or contoured surface area can be sized to retain a length of cable31sufficient to dispose the article22connected to the cable31between a fully lowered position and a fully raised position. Alternatively, the drum25can have a smooth surface about which the cables31can be wound and from which the cables31can be unwound in a side-by-side manner.

The drum25may be rotatably connected to a the tube11and operably connected to the motor driveshaft29with a linking element, such as a belt, chain, or other linking mechanism. As shown inFIG. 3, the drum25can be operably connected to the first traction drive26with a drum drive belt34.

Traction Drives

In some embodiments of the present invention, the lift assembly system10can include one or more traction drives26,27. The traction drives26,27can be rotatable such that elongate members31such as cables can move about the rotating surfaces of the traction drives26,27. The traction drives26,27can include a series of channels59or contoured surface areas, similar to the channels59or contoured surface areas in the drum25, about which the cables31can travel. The traction drives26,27can be referred to as “sheaves”. A sheave is defined for purposes herein as a wheel or disc with a grooved rim, especially one used as a pulley.

As shown inFIGS. 2-5, an embodiment of the lift assembly10can include two traction drives26,27that are operably linked with each other and with the drum25with one or more chains, belts, or other linking mechanisms. For example, as shown inFIG. 3, the drum drive belt34can operably connect the first traction drive26and the drum25so that rotation of the first traction drive26causes corresponding rotation of the drum25in the same direction. A second traction drive belt35can operably connect the first traction drive26and the second traction drive27so that rotation of the first traction drive26causes corresponding rotation of the second traction drive27in the same direction. As such, the drum25and first and second traction drives26,27, respectively, can move together in a coordinated, simultaneous fashion so as to provide synchronous movement of the cables31.

In certain embodiments, the traction drives26,27can be positioned relative to each other and to the path of travel of the cables31such that the traction drives26,27place tension on the cables31and thereby help to maintain the cables31in a desired position as the cables31travel along a path. For example, as shown inFIGS. 2 and 3, the first traction drive26can be positioned between the drum25and the tube11and the second traction drive27can be positioned between the first traction drive26and the tube11, such that the cable31can extend along a generally horizontal path from the drum25to and about the second traction drive27, to and about the first traction drive26, and then to the head block39. Alternatively, as shown inFIGS. 4 and 5, the first traction drive26can be positioned between the drum25and the tube11and the second traction drive27can be positioned between the drum25and the first traction drive26, such that the cable31can extend along a generally horizontal path from the drum25to and about the first traction drive26, to and about the second traction drive27, and then to the head block39. As a result, the traction drives26,27can serve to keep the cables31in aligned positions as they travel from the drum25to the head block39and/or loft blocks32. The use of two cooperating traction drives26,27can increase the lifting (torque) capacity on the cables31, thereby increasing the load capacity of the lift system10. As a result, the ability of the lift assembly system10to safely support and move a load can be increased.

Drive Mechanism

In some embodiments of the present invention, the lift assembly system10can include a drive mechanism23. The drive mechanism23may include a motor28, for example, an electric motor28. The drive mechanism23may further include a set of gears (not shown), which may be housed in a gear box30, for transferring rotational motion of the motor28to the drive shaft29and in turn to the first traction drive26. The drive mechanism23can be housed in a drive mechanism housing24, as shown inFIG. 1. The motor28can cause rotation of the first traction drive26about its rotational axis. In embodiments in which the second traction drive27and the drum25are operably linked to the first traction drive26, the motor28and gears can likewise cause rotation of the second traction drive27and the drum25. The motor28may be any of a variety of high torque motors such as alternating current inverter duty motors, direct current motors, servo motors, or hydraulic motors.

The gears (not shown) in the gear box30can rotate the drive shaft29, and the traction drives26,27and drum25, in a winding (raising) rotation and an unwinding (lowering) rotation. A desired gear ratio may be determined by a number of factors, including, for example, the anticipated loading, the desired lifting rates (speeds), and the capacity of the motor28. The gears may provide a speed-reducing mechanism to reduce the rotational speed of the motor28to an output speed of the drive shaft29that is suitable for rotating the traction drives26,27and drum25.

The first traction drive26and the drum25can be operably connected with the drum drive belt34, as described. In some embodiments, the first traction drive26and the drum25can rotate at predetermined relative speeds, or rates. When cables31are wound about the drum25such that the article22attached to the cables31is moved to its uppermost position, the cable lengths about the drum25create a circumference of the combined drum25and cables31that is greater than the circumference of the drum25alone. Thus, in certain embodiments, as the motor28rotates the first traction drive26at a first speed, due to the larger drum-cable circumference, the drum25can be rotated initially at a second, lower speed relative to the first rotational speed of the first traction drive26. During an unwinding operation, the first traction drive26can rotate constantly at the first speed. Due to the progressively smaller drum-cable circumference during unwinding, the drum25can be rotated at increasing speeds relative to the initially lower second speed of the drum25, in order for the cable31to move about the first traction drive26at the same rate as it unwinds from the drum25. Unwinding the cables31from the drum25and about the first traction drive26at the same rate helps maintain a constant tension on the cables31.

Likewise, when the cables31are unwound from the drum25such that the article22attached to the cables31is moved to its lowermost position, the cable lengths about the drum25create a circumference of the combined drum25and cables31that is greater than the circumference of the drum25alone but less than the drum-cable circumference when the cables31are fully wound about the drum25. During a winding operation, the first traction drive26can rotate constantly at the first speed, and the drum25can rotate initially at the same first speed as that of the first traction drive26. Due to the progressively larger drum-cable circumference during winding, the drum25can be rotated at decreasing speeds relative to the first speed in order for the cable31to move about the first traction drive26and wind about the drum25at the same rate. Winding the cables31about the first traction drive26and onto the drum25at the same rate helps maintain a constant tension on the cables31.

In some embodiments, the drive mechanism23can include a tension clutch37, as shown inFIG. 3. The tension clutch37can allow the drum25to rotate at a different speed relative to the rotational speed of the first traction drive26so as to accommodate the variable drum-cable circumference related to the amount of cable31wound about the drum25at particular times during winding and unwinding of the cables31. For example, as the cables31are unwound from the drum25and the drum-cable circumference becomes smaller, the tension clutch37can decrease tension on the drum25so as to allow the drum rotational speed to increase relative to the initially lower second rotational speed of the drum25. As the cables31are wound about the drum25and the drum-cable circumference becomes larger, the tension clutch37can increase tension on the drum25so as to allow the drum rotational speed to decrease relative to the constant speed of the first traction drive26. In this manner, the cables31can be wound about and unwound from the drum25and about the first traction drive26at the same rate so as to maintain a constant tension on the cables31.

The drive mechanism23arrangement can provide for control of the tension and movement of the cables31. As such, the drive mechanism23can provide the advantage of allowing some embodiments of the lift assembly system10to be utilized without the use of counterweights. In some embodiments, the drive mechanism23, and thereby the lift system10, can be controlled in an automated manner, for example, by a computer49. In certain embodiments, the drive mechanism motor28may be actuated by a remote control device (not shown).

In some embodiments, as shown inFIG. 3, a pressure roller19can be positioned adjacent each of the first and second traction drives26,27, respectively, to maintain a consistent pressure on each cable31routing about the traction drives26,27. For example, the pressure roller19can be positioned above each of the first and second traction drives26,27, respectively, and configured to apply positive, downward pressure on each cable31at the point in the cable's31path of travel in which it contacts the particular traction drive26or27. In some situations a load attached to the cables31may be unevenly distributed across a plurality of cables31to which the load is attached. As a result, the cables31can be more tightly wound onto one portion of the rotating surface of the traction drives26,27than onto another portion. For example, cables31having a heavier load portion can sink into the channels59in the traction drives26,27more deeply as they are wound about the traction drives26,27than cables31having a relatively lighter load portion. As uneven load pressure can cause one or more cables31to sink into the channel(s)59unevenly, the various loft block32-cable31diameters can likewise be uneven, which can result in undesirable changes in the orientation, or levelness, of the attached load. By placing positive pressure with the pressure roller(s)19on each of the cables31as they route about the traction drive(s)26,27, evenly distributed pressure on cables31as they route about rotating surface of the traction drive(s)26,27can be maintained. As a result, the orientation of the load can remain constant as the load is raised and/or lowered.

In certain embodiments, the drive mechanism23may include the pressure roller19in operative contact with the first traction drive26, with the second traction drive27, or with each of the traction drives26,27. The pressure roller(s)19may be fixed in position at a predetermined distance from the traction drives26,27. Alternatively, the pressure roller(s)19may be configured so as to be movable from one distance from the traction drive(s)26,27to another distance from the traction drive(s)26,27. In this manner, the pressure roller(s)19can be adjusted to accommodate various cable diameters and/or various loads.

In some embodiments, the drive mechanism23can be located completely external to the tube11containing the loft blocks32. Some embodiments of the lift assembly10can be equipped with different sizes and capacities of motors28. As an example, a five horsepower electric motor28can be exchanged for a 10 horsepower motor28or a 15 horsepower motor28when greater power is desired for moving heavier objects.

As shown inFIG. 1, the lift assembly10can include a cover or housing24for the drum25, first and second traction drives26,27, respectively, and other drive mechanism23components.

Elongate Members

Some embodiments of the lift assembly system10can be constructed to cooperate with at least one elongate member31, such as a cable, or other length of material, connected at one end to the drum25and at the other end to the article22or load to be moved. In some embodiments, the number of cables31can be at as many as eight or more cables31. As used herein, “cable” is defined as a steel cable, steel tape (for example, a one inch wide steel band), wire, metal, natural or synthetic rope, or other any other generally inelastic windable material suitable for raising and lowering a load.

The cables31can have various constructions and dimensions suitable for fitting about the drum25, traction drives26,27, head block39, and loft blocks32and for supporting loads attached to the cables31. For example, the cables31can have multiple strands twisted together to provide increased tensile strength. In some embodiments, the cables31can have a diameter larger than the 3/16 inch diameter cables31used in conventional lift assemblies. For example, certain embodiments of a lift assembly system10of the present invention can accommodate a cable31having a ¼ inch diameter or greater. An increased cable diameter can provide increased tensile strength for supported heavy loads without breaking. In alternative embodiments, the cable31may have a 3/16 inch diameter or smaller.

A length of cable31can be disposed about each channel59in the drum25sufficient to wind about the first and second traction drives,26,27, respectively, to extend horizontally to the head block39and to the loft block32around which it moves, and then downward to the point at which it is connected to the article22or load. The cable31can have a length sufficient to fully lower a desired article22or load. In some embodiments, each loft block32can be positioned at different intervals along the length16of the tube11, and thus at a different distance from the drum25. As a result, the cable31that is routed about each loft block32may be a different length than each other cable31.

Compression Tube

In another aspect of the present invention, some embodiments of the lift assembly system10can include the compression tube11as shown inFIGS. 1,2,5,7, and11. The compression tube11can comprise a length of substantially rigid material that can be connected to an overhead building structure87. As shown inFIG. 2, the compression tube11can include a plurality of loft blocks32, or pulleys, disposed at intervals along the inside length16of the tube11. Each loft block32can rotatingly engage one or more cables31. The loft blocks32can re-direct the generally horizontal path of the cables31from the drum25and traction drives26,27to a generally vertical path to the attached article(s) below the compression tube11.

Depending upon several factors, including, for example, the dimensions and weight of the article22to be raised and/or lowered, the number of loft blocks32utilized in an embodiment of the present invention can vary. In some embodiments, for example, the lift assembly system10can include eight loft blocks32and thus eight cable drop points, as compared to some conventional lift assemblies which provide seven or fewer loft blocks32, thus providing greater support to the article22and greater flexibility as to locations on the article22to which the cables31can be attached.

In some embodiments, the loft blocks32can be secured at an infinite number of locations along the longitudinal continuum, or length16, of the compression tube11, thus providing flexibility as to locations on the article22to which the cables31can be attached. In some embodiments, each loft block32can be connected to a loft block slider33having a locking mechanism64. The loft block sliders33and connected loft blocks32can be moved for positioning at a particular location along the length16of the compression tube11. In certain embodiments, the compression tube11can include a means for engaging the loft blocks32. For example, the means for engaging the loft blocks32can include a rail57extending outwardly into the interior of the tube11. Each of the loft block sliders33can have a groove62along its length adopted to slidingly engage the tube rail57. Alternatively, the means for engaging the loft blocks32can include a channel in the length16of the opposing walls of the tube11. Each of the loft block sliders33can have an arm extending outwardly from each side of the loft block sliders33that can slidingly engage the channels along the tube11. In such configurations, the loft block sliders33and connected loft blocks32can be positioned at a substantially infinite number of locations along the length16of the tube11. Once the loft block32is in a desired position along the length16of the tube11, the locking mechanism64can be actuated to secure the loft block32in that position.

In some embodiments, the lift system10can include the head block39secured within the compression tube11. In certain embodiments, the head block39can be secured at the head block end21of the tube11opposite the drive end20to which the drive mechanism23is attached. The head block39can be located to redirect the elongate member31, or cable, from a first generally horizontal path from the drive mechanism23to a second generally horizontal path to the loft blocks32back in the direction of the drive mechanism23. The head block39can include channels59for aligning and directing each of a plurality of the cables31. As shown inFIG. 11, certain embodiments of the head block39can include a bifurcated rotating surface such that the cables31can be spaced apart into two groups so as to provide a space in the center along the length16of the tube11for locating the loft blocks32. In such a configuration, one of the centermost cables31on one side of the bifurcated head block39can be routed to the loft block32nearest to the head block39, so as to decrease the fleet angle of the cable31between the head block39and the loft block32. The other centermost cable31(on the other side of the bifurcated head block39) can be routed to the loft block32second nearest to the head block39. The other cables31can then be alternatingly routed to loft blocks32subsequently farther from the head block39. Such a configuration can provide for optimal fleet angles of the cables31and an even distribution of the load attached to the cables31.

The compression tube11can include an opening17in the bottom15of the tube11along at least a portion of the length16of the tube11. The cables31that are routed about the loft blocks32can be routed downward through the opening17for movement upward and downward to raise and lower the attached article22.

In some embodiments, for example, as shown inFIGS. 1 and 12, the compression tube11can include a connecting mechanism disposed on the top14of the tube11for connecting the tube11to an overhead structure87, such as a building support beam. The connecting mechanism can comprise connector arms18that can be movable toward and away from each other. The connecting mechanism can include a tightening mechanism, such as a biasing mechanism, for releasably securing the connecting mechanism about the structure87. For example, the tightening mechanism can include a threaded rod threaded through openings in each of the connector arms18that can be rotated so as to move the arms18closer to each other and about the overhead structure87.FIG. 12illustrates another embodiment of a tube overhead connector mechanism, described herein. The tube11may be connected to the overhead support structure87in other manners and utilizing other connecting mechanisms.

Some embodiments of the lift assembly system10can include a single primary compression tube11unit having a predetermined length. Such a primary compression tube11unit can be made in any desired length, for example 20 feet. If a stage, or proscenium, opening is for example, 40 feet across, two 20-foot compression tubes11can be installed end-to-end to provide a means for raising and lowering an article, such as a curtain, across the entire opening.

In other embodiments, the lift assembly system10can include a primary compression tube11unit and one or more extension units of the compression tube11. In such embodiments, the extension tube11unit(s) can include a desired number of loft blocks32, and can be installed end-to-end with the primary tube11unit to provide a length of compression tube11having various desired lengths. In this arrangement, the lift assembly system10can include a single drive mechanism23at one end of the primary tube11unit. The cables31to be routed through the bottom15of the extension tube11unit can be routed from the single drive mechanism23on the drive end20of the primary tube11through the opposite end of the primary tube11, to the head block39, if included, and to the loft blocks32in the extension tube11. In this manner, the lift assembly system10can include various lengths of the compression tube11and various numbers of the loft blocks32for routing a corresponding number of the cables31to the article22to be moved. For example, one compression tube11may include eight loft blocks32, and two end-to-end compression tubes11may contain 16 loft blocks32. The compression tube11and/or extensions can be made in standardized lengths for modular use, for example, in lengths of 20 feet, 10 feet, and/or five feet. Alternatively, compression tubes11and/or extensions can be manufactured in customized lengths.

The compression tube11can be made in various manners. In one embodiment, the tube11can be extruded using a material such as aluminum, steel, an alloy, or other material. The compression tube11can comprise any material that is sufficiently strong to support the components contained inside the tube11and the load placed on the loft blocks32from the article22attached to the cables31. In some embodiments, the material can be a lightweight material so as to reduce the overall weight of the lift assembly system10. In other embodiments, the compression tube11can be molded from such materials.

In another aspect of the present invention, the configuration of the compression tube11in combination with the drive mechanism23can decrease or eliminate substantially all of the horizontal load stress on a ceiling and/or roof structure to which the lift assembly system10is mounted. In conventional lift systems, the drive mechanism23and the loft blocks32are often mounted to physically separate structures in a building, for example, different overhead beams. As a result, a load being moved by the cables31can place a horizontal stress between the overhead structural building supports to which the drive mechanism23is attached and the supports to which the loft blocks32are attached. Such horizontal stress between building support structures may cause loosening or weakening of those support structures and thus be undesirable. In some embodiments of the present invention, as shown inFIG. 1, the compression tube11(to which the loft blocks32are attached) and the drive mechanism23can be physically, or structurally, connected or integrated, for example, by welding or otherwise fastening together. In this manner, the horizontal stress between the drive mechanism23and the loft blocks32can be absorbed by the structure of the lift assembly10, rather than being displaced onto building support structures to which separate components of the lift assembly10are attached.

In some embodiments, the compression tube11can be constructed of a substantially rigid material, for example, aluminum, steel, an alloy, or other material. The tube11may be adapted to absorb some of the horizontal load placed on the attached loft blocks32, by sliding, or “floating,” along the longitudinal axis, or length16of the tube11. As horizontal stress is placed on the tube11by pressure on the cables31between the drive mechanism23and a load attached to the cables31, the compression tube11can absorb at least a portion of that horizontal stress by “compressing,” or moving slightly, for example, one to two inches, in the horizontal direction between the overhead support structures87to which it is attached. As described herein, the tube11may be fixedly attached at one point of contact on the tube11to one overhead support structure87, and the tube can be slidably connected at one or more other points of contact to other overhead support structure(s)87. In this manner, the compression tube11can compress horizontally and thereby absorb horizontal stress. As a result, the horizontal load stress on individual building supports experienced in conventional lift assemblies can be substantially decreased or eliminated in embodiments of the lift system10of the present invention.

A plurality of the compression tubes11containing a plurality of the loft blocks32and the cables31can be engaged with multiple overhead support structures87such that adjacent compression tubes11abut each other along a longitudinal dimension. As a result, multiple compression tubes11installed in an abutting relation can contact each other and cooperate to absorb, and thus decrease, the horizontal load on the overhead structure87, thereby reducing any relative movement between the overhead structures87.

In certain embodiments, the lift assembly system10can be supported as a free-standing unit. As an example, the lift assembly system10can be supported on each end20,21with vertical posts that are independently secured in position. For example, vertical posts can be driven into the ground, set in concrete, or otherwise supported from the bottom. In this manner, an embodiment of the lift assembly system10can be used in settings without the need for an overhead support structure87such as the roof of a building.

Cable Belt

In an alternative embodiment, as shown inFIG. 6, the lift assembly system10can include a first drum45and a second drum46(or bifurcated portions of the drum25), each drum45,46being axially aligned with and operably connected to the drive shaft29of the drive mechanism23. A first cable belt47can be attached to the first drum45, and a second cable belt48can be attached to the second drum46. The first and second cable belts47,48, respectively, can comprise various materials, for example, a windable steel tape. The cable belts47,48can be wound about and unwound from the respective drums45,46. The cable belts47,48, or tapes, can each have a width corresponding to the width of a plurality of cables31. A plurality of the cables31, for example, eight cables31, can be attached to the distal end of each of the first and second cable belts47,48, respectively. A plurality of cables31can be attached to the respective cable belts47,48in various manners. One example of a means for connecting the cables31to the cable belts47,48is the cable connector38, as shown inFIGS. 7-9.

In such an embodiment, the head block39can be positioned inside the head block end21of the compression tube11opposite the drive mechanism23. The first and second cable belts47,48, respectively, can move through at least a portion of the length16of the compression tube11to near the head block39. Each of the individual cables31can be routed around the head block39and then to one of the loft blocks32along the length16of the compression tube11.

Braking Mechanism

In another aspect of the present invention, some embodiments of the lift assembly system10may include a braking mechanism36. The braking mechanism36can be an overspeed braking system. As shown inFIGS. 2 and 3, the brake36can be a “load-side” overspeed brake. That is, the brake36can be attached to a lift assembly10component other than the motor28. In this configuration, should the motor28and/or gears controlling speed of cable movement fail, the lift assembly system10can provide a braking mechanism36separate from operation of the drive mechanism23for preventing free fall of a load attached to the cables31. In this manner, the load-side brake36can provide redundancy relative to the power-train components for controlling downward movement, for example, slowing or stopping, of a load attached to the cables31.

Conventional lift assemblies often used “motor-side” brakes, which can overheat with repeated cycles of moving a load upward and downward in quick succession. An advantage of using a “load-side” braking mechanism36as in some embodiments of the present invention is that such overheating related to repetitive movements of the lift mechanism can be avoided.

In some embodiments, the overspeed brake can be a “Weston” type brake, for example, as described in U.S. Pat. No. 4,009,770 to Schreyer or in U.S. Pat. No. 6,889,958 to Hoffend, Jr. In other embodiments, the braking mechanism36can include mechanical, electrical, pneumatic, hydraulic, and/or clutch components for the slowing and/or stopping of the free-fall of a load.

In another embodiment, the braking mechanism36can comprise a flexible arm (not shown), such as a piece of flexible steel or aluminum, connected to the cables31. The flexible arm can be similar to a pawl-type arm. Tension on the cables31from an attached load can bias the flexible arm toward the bottom15or a side12,13of the compression tube11. When tension on the cables31is released, for example, in the event that the drive train components fail, the biasing force on the flexible arm is removed and the arm can flex and spring upward or sideward into engagement with a portion of the compression tube11, such as the top14of the tube11or the side12,13of the tube11opposite the biased position of the flexible arm. The top14or side12,13of the compression tube11interior into which the flexible arm can spring into engagement can include a series of angled teeth similar to a ratchet configuration that can further engage the flexible arm. In this way, the cables31attached to the flexible arm can be engaged with a surface in the interior of the compression tube11and thereby stop free-fall of the cables31and attached load. In an embodiment, a shock absorbing material can be placed between the arm-engaging surface and the interior surface of the compression tube11to help reduce undesirable stress on the tube11in the event that the flexible arm suddenly engages the arm-engaging surface during a free-fall of a load attached to the cables31.

In another embodiment, the load-side braking mechanism36can be connected to the elongate member31, for example, between a cable belt47,48and a plurality of cables31, and movable within the tube11. As shown in the embodiment inFIG. 12, the braking mechanism36can include a pair of brake cables76extending the length16of the tube11and secured to each end of the tube11. A pair of spaced-apart plates77having grooves78in internal faces of the plates77can be configured for sliding about the pair of brake cables76. A brake assembly79disposed between the plates77can comprise a pivot structure80and a rocker arm81at the connection with the elongate member31. When tension on the elongate member31exerted by the drive mechanism23decreases below a preset threshold, the pivot structure80can pivot86so that the rocker arm81engages the brake cables76, thereby stopping movement of the elongate member31.

In another embodiment of a braking mechanism36, a braking member (not shown) can be attached to the outside of each of the outer cables in a plurality of the cables31. The two braking members can be attached to the cables31such that the braking members are held in place at a distance from the sides of the compression tube11with the tension on the cables31exerted by an attached load. The braking members can be arranged at a diagonal, such as in a “V” pattern, relative to the longitudinal axis, or length16, of the tube11. When load-induced tension on the cables31is released, such as during the free-fall of the cables31and attached load, the braking members can move apart and into braking contact with the sides12,13of the compression tube11. The sides12,13of the compression tube11and/or the sides of the braking members facing the sides12,13of the tube11can include a brake pad type of material to provide a friction interface for slowing the braking members to a stop when the braking members contact the sides12,13of the tube11. In this way, the cables31attached to the braking members can be engaged with a surface in the interior of the compression tube11and thereby stop free-fall of the cables31and attached load.

In another embodiment of the lift assembly system10, the braking mechanism36can include the cable connector38. For example, as shown inFIGS. 7-9, the cable connector38can include two portions, a first portion (or male portion)40which fits within at least a part of a second portion (female portion)41. The two portions40,41of the cable connector38can be secured to each other with a fastener42, for example, a screw, through overlapping portions of the male and female portions40,41, respectively, of the connector38. The two portions40,41of the cable connector38can be fastened together such that each portion can swivel, or pivot, within a limited span relative to the other portion40,41. The male portion40can include a peg43extending perpendicularly through an arcuate opening44in the female portion41. The combination of the peg43and arcuate opening44can serve to limit the extent of pivoting, or swiveling, between the male and female portions40,41, respectively, of the connector38. The cable connector38can be referred to as a “clew.”

The cable connector38, or “clew,” can be adapted to be inserted in the lengths of the cables31such that the cable connector38can connect one end of a plurality of the cables31to another end of the plurality of the cables31. That is, each of the cables31can be divided, or cut, into two separate portions. Each of the divided ends of the cables31can be secured to one of the portions of the cable connector38. The cable connector38can travel along the path of travel of the cables31within the compression tube11. In the event that one of the plurality of cables31experiences a loss of tension due to, for example, becoming disconnected from a load or from breaking, the lateral tension on the cable connector38from the remaining cables31can cause the cable connector portions40,41to pivot, or swivel, relative to each other. When the cable connector portions40,41swivel to one side, the side of the cable connector38can contact the side12,13of the compression tube11. In this way, movement of the cables31and attached load can be slowed so as to prevent undesired downward movement of the load. In certain embodiments, the sides of the cable connector38and/or the sides12,13of the compression tube11can include a brake pad type of material to provide a friction interface for slowing and/or stopping the cables when the cable connector38contacts the side12,13of the tube11.

Sensor

In another aspect of the present invention, some embodiments of the lift assembly system10can include a safety mechanism for slowing and/or stopping downward movement of the cables31and attached article(s)22upon detection of an obstacle in an intended path of travel.

In such an embodiment, the safety mechanism can include a sensor (not shown) attached to cable(s) that can be adapted to sense if an object other than an intended surface (such as a floor or the ground) is underneath it. The motor28can be adapted to alter movement, for example, interrupt, stop, and/or reverse movement, of the cables31, and the attached article(s)22, in response to a signal from the sensor indicating presence of an undesired object in the intended path of travel. For example, if a person walks underneath a descending article22attached to the cables31, the sensor can detect the presence of the person and signal the motor28that an object is in the path of travel of the article22. The motor28can then interrupt, stop, and/or reverse movement of the cables31, and the attached article22. The motor28can be programmed so that once the object obstructing the article's path of movement is removed from the path of movement, for example, when a person moves from underneath the descending article22, the motor28can be automatically actuated to resume downward movement of the article22.

The sensor can be a laser, ultrasonic, infrared, photoelectric, mechanical, proximity, or other type of sensor capable of sensing presence and/or absence of an object in an intended path of travel. In some embodiments, the sensor may be connected to the article22, to a batten, or to one or more cables31. In certain embodiments, the sensor can be sized and colored to reduce visibility by a viewing audience.

The sensor may be operably connected to a controller, such as the computer49, by a wire or wireless connection. The signal sent by the sensor indicating an undesirable object or obstruction in the article's path of movement can be received by and processed by the computer49. Once the computer49processes the signal from the sensor, the computer49can send a signal to alter operation of the motor28in a predetermined manner, such as stopping rotation of the motor28.

Controller

In another aspect of the present invention, some embodiments of the lift assembly system10can include a controller for controlling the drive mechanism23, and thereby movement of the cables31and attached article22or load. The controller can be a dedicated device or, alternatively, can include software for running on a personal computer49, wherein control signals are generated for the lift assembly10. In some embodiments, the controller can include an algorithm designed for safety. For example, if an obstruction is detected by a sensor, the processor may automatically slow descent of the cables31and attached article(s)22to a lower downward velocity and/or stop movement altogether.

The controller may be programmed to process signal(s) from sensor(s) attached to the cable(s)31and/or attached article(s)22to determine the distance a particular point along the length of the cable31and/or article22is from the surface (such as a floor or the ground) below the cable31and/or article22. For example, one or more sensors can be placed on the ends of the cables31that can be adapted to sense the distance between the ends of the cables31, and thereby the bottom of the article22, and the floor below, and send a signal to the computer49indicating that distance. The computer49can be programmed to perform various operations in response to the cable end location signal. For example, the computer49can slow and/or stop movement of the cable31and attached article22, change orientation of the article22relative to the floor or other points of reference, reverse direction of movement of the article22at a predetermined time following receipt of the cable end location signal, as well as other operations.

Control of the lift assembly10, and particularly the drive mechanism23or motor28can be accomplished by a dedicated processor operably connected to the lift assembly system10. The processor can be operably connected to the drive mechanism23, and specifically the electric motor28, to control a variable speed of the motor28. The processor can be configured, or include code, to perform a number of functions, including, for example, control of the associated lift assembly10; queuing functions; timing or duration of a particular drive state; controlling the motor28to locate the connected load at a predetermined location; translating a load at a specific speed (velocity); and/or controlling an acceleration to a given speed as well as a deceleration to a given speed. In an exemplary embodiment, the computer49processor may be configured to: (1) rotate the drum25at a first velocity in a first rotational direction; (2) rotate the drum25at a second velocity in a second, different rotational direction; (3) accelerate the drum25rotation in the first rotational direction; (4) accelerate the drum25rotation in the second rotational direction; (5) rotate the drum25a first amount in the first rotational direction; and/or (6) rotate the drum25a second amount in the second rotational direction.

In some embodiments, the computer49, for example as shown inFIG. 10, may comprise a processor or processors (not shown). A computer-readable medium, such as a random access memory (RAM), can be coupled to the processor. The processor can execute computer-executable program instructions stored in memory, such as executing one or more computer programs for operating the lift assembly. Such processors may comprise a microprocessor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), field programmable gate arrays (FPGAs), and state machines. Such processors may further comprise programmable electronic devices such as programmable interrupt controllers (PICs), programmable logic controllers (PLCs), programmable read-only memories (PROMs), electronically programmable read-only memories (EPROMs or EEPROMs), or other similar devices.

Such processors may comprise, or may be in communication with, media, for example computer-readable media, that may store instructions. When executed by the processor, the instructions can cause the processor to perform the steps described herein as being carried out, or assisted, by a processor. Certain embodiments of computer-readable media may comprise, but are not limited to, an electronic, optical, magnetic, or other storage or transmission device capable of providing a processor with computer-readable instructions. Other examples of media comprise, but are not limited to, a floppy disk, CD-ROM, magnetic disk, memory chip, ROM, RAM, ASIC, configured processor, optical media, magnetic tape or other magnetic media, or any other medium from which a computer processor can read instructions. Instructions may be transmitted or carried to a computer using various other forms of computer-readable media, such as a router, private or public network, or other transmission device or channel. The processor, and the processing, described may be encompassed in one or more structures, and may be dispersed through one or more structures. The processor may comprise code for carrying out one or more of the methods (or parts of methods) described herein.

In another aspect of some embodiments of the present invention, the computer49may be programmed to send a signal to the motor28to change the rate of movement of the cables31and attached article22at particular points along the path of movement. For example, in certain embodiments, the computer49may be programmed to decelerate downward movement of the cables31and attached article22when the article22reaches a predetermined distance from the surface below the article22. That is, the cables31and article22may be lowered toward the surface below at a first rate. When the article22, such as a stage curtain, reaches a particular distance from the stage floor below, for example, two feet above the stage floor, the computer49may signal the motor28to decelerate movement to a second, slower rate of descent until the bottom of the stage curtain reaches the stage floor.

In certain embodiments, the computer49may be programmed to change the direction and/or rate of movement of the cables31and attached article(s)22at particular intervals. The changes in direction and/or rate of movement of the article(s)22can be coordinated with an artistic performance. For example, the computer49can be programmed to actuate the motor28to move a piece of background scenery, such as a depiction of the sun, upward at a slow rate from one direction to indicate rising of the sun. The computer49can be programmed to actuate the motor28at a predetermined time to then move the sun scenery rapidly downward in the opposite direction to indicate the quickly approaching nightfall. Accordingly, the computer49can be programmed to actuate the motor28to move the cables31and attached article(s)22in various directions and rates of movement for dramatic effect.

In another embodiment, the computer49processor may be configured to rotate the drum25in a direction, amount, and velocity corresponding to the direction, amount, and velocity of rotation of a drum25in another lift assembly. That is, the controller/processor49can include the ability to communicate with one or more interconnected lift assemblies10and control coordination of the operation of each of those lift assemblies10. As examples, in particular theatrical productions, multiple lift assemblies10may be controlled by a single controller to raise and/or lower a vehicle, a platform on which performers can position themselves, or a fish tank while maintaining a substantially level water level in the tank.

As shown inFIG. 10, the controller can include a computer49and a computer video display52useful for operating a processor for controlling embodiments of the lift assembly system10. In some embodiments, a user interface can be provided to facilitate operation of the processor and the lift assembly10by a user. For example, the user interface can include a laptop computer, keyboard50, mouse51, touch screen, computer video display terminal52, remote control device, and/or other input device. The user interface components can allow an operator to monitor, control, override, change operational parameters, and otherwise operate each of the functions and safety features of embodiments of a single lift assembly10or multiple interconnected lift assemblies10of the present invention.

Assembly of Lift System

Some embodiments of a lift assembly system10of the present invention can be manufactured and/or assembled in an efficient manner. Some embodiments can include up to 75 percent fewer components as compared to conventional lift assemblies (for example, 50 parts vs. 200 parts). Fewer components can decrease the complexity of the mechanical arrangement of the lift assembly system10. Fewer components can also substantially decrease the manufacturing cost (for example, up to 60 percent less cost) as compared to conventional lift assemblies.

Due to the streamlined footprint of the assembled tube11and drive mechanism housing24, embodiments of the lift assembly system10of the present invention can be assembled in a substantially smaller floor space relative to that required for manufacturing conventional lift systems. In some embodiments, the assembly process can be at least partially automated. Efficiency with respect to required assembly space (for assembling fewer components) in embodiments of a lift assembly system10of the present invention can reduce the manufacturing costs as compared to conventional theater rigging systems.

Shipping and Installation

In another aspect of the present invention, some embodiments of the lift assembly system10of the present invention can be packaged for shipping to a customer for quick and easy installation. That is, the lift assembly system10can be packaged having all components ready for operation upon mounting to the overhead support structure87. For example, the cables31can be pre-routed from the drum25around the two traction drives26,27and around the head block39and the loft blocks32inside the compression tube11. Once the integrated compression tube-drive mechanism system is mounted to the overhead support structure87, the loft blocks32can be moved by hand (for example, by depressing the tabs63as shown inFIG. 11) or with a small tool into desired positions along the length16of the tube11. Once in position, the loft blocks32can be securely fastened to the compression tube11and the cables31dropped through the longitudinal opening17in the tube11for attachment to the article22. Such a ready-to-operate installation avoids the need to route cables31through their path of travel, and can be accomplished without any special tools. Installation may be accomplished by persons not having training or experience with such rigging or installation of lift systems, for example, an electrical contractor.

Some embodiments of the present invention can comprise substantially less overall size, or footprint, than conventional theater rigging systems. An overall smaller size can be advantageous for handling during shipping. For example, a conventional lift assembly may be shipped in a shipping crate that is approximately 14 feet in length. Some embodiments of a lift assembly10of the present invention can be shipped on a typical three foot square shipping pallet. That is, the space required for shipping an embodiment of a lift assembly10of the present invention can be substantially less than that required by a conventional lift assembly. As a result, an embodiment of the present invention may be loaded and unloaded from a shipping vehicle using a regular-sized forklift rather than an oversized forklift that may be required for larger conventional lift assemblies.

Some embodiments of the lift assembly can provide a modular, self-contained unit that can be readily installed in a wide variety of building configurations. Due to the decreased overall size, some embodiments of the lift assembly10of the present invention can be installed in almost any existing building construction or configuration. Decreased space requirements for installation in combination with fewer assembled components can result in embodiments of the present invention being installed more easily and more quickly, thus decreasing installation costs.

FIGS. 11-13show illustrative embodiments of aspects of the present invention. In some embodiments, the lift assembly system10can include a substantially rectangular tube11having a front and a rear C-shaped portion connected together to form a front12, rear13, top14, and bottom15of the tube11. InFIG. 11, the top14and front12portions of the tube11have been removed to show the arrangement of components inside the tube11. The C-shaped portions of the tube11can be configured such that when the portions are connected together, the bottom15edges of the front and rear portions remain spaced apart, thereby providing the opening17in the bottom15along at least a portion of the length16of the tube11. The tube11can be connectable to the overhead structure87, such as a building support beam.

The lift system10can include the drum25positioned externally to the tube11, as shown inFIGS. 2-5. The drum25can be adapted to wind and unwind one or more elongate members31, such as cables, to raise and lower the article22attached to the elongate members31. The lift system10can further include the drive mechanism23, as shown inFIGS. 2-5, structurally connected to the drive end20of the tube11externally. The drive mechanism23can comprise the motor28rotatingly connected to the first traction drive26and operably connected to the drum25and to the second traction drive27. In such a configuration, the elongate member31can extend along a first generally horizontal path from the drum25about the first and second traction drives26,27, respectively, to the tube11.

The head block39can be fixedly connected to the head block end21of the tube11opposite the drive end20. The head block39can rotate about a head block axle55, which is supported on either side of the head block39in a head block axle support54. A head block mount53can be attached to and extend from the axle support54on each side of the head block39. The head block mount53can be rotated into alignment with a surface of the tube11and be fastened to the tube11so as to secure the head block39to the tube11. The head block39can be located to redirect the elongate member31from the first generally horizontal path to a second generally horizontal path from the head block39back toward the drive mechanism23.

The loft block32can be spaced from the head block39and connected to the tube11internally. The loft block32can be located to redirect the elongate member31from the second generally horizontal path to a generally vertical path through the bottom opening17in the tube11to the attached article22. In some embodiments, the lift system10can include a plurality of the loft blocks32. Each loft block32can be positioned at an infinite number of locations on the continuum along the length16of the tube11.

The loft block32can further include the loft block slider33adapted to position the loft block32at a desired location along the length16of the tube11. The loft block slider33can comprise a front slider arm58spaced apart from a rear slider arm60, and a support bar61on each end of the loft block slider33connecting the front and rear slider arms58,60, respectively. A loft block axle (not shown) can be supported on one end by the front slider arm58and on the opposite end by the rear slider arm60. The loft block32can be rotatingly attached about the loft block axle. Each of the front and rear loft block slider arms58,60, respectively, can include a groove62along the length16of the slider arm58,60. The groove62an be adapted to slidingly engage a respective lower front rail or lower rear rail57along the length16of the tube11. By sliding the loft block slider groove62along the lower tube rails57, the loft block32can be positioned at a desired location along the length16of the tube11.

The loft block slider33can further include a locking mechanism64disposed on each of the front and rear slider arms58,60, respectively, for locking the loft block in a desired position along the length16of the tube11. In the embodiment shown inFIG. 11, the loft block slider locking mechanism64can include a tab63located on each end of the front and rear slider arms58,60, respectively, and a biasing mechanism attached to each tab63. When the tabs63are depressed, the biasing mechanism is released and the loft block slider33can be slid along the front and rear tube rails57. When the tabs63are released, the biasing mechanism is actuated so as to lock the loft block32onto the front and rear tube rails57.

In some embodiments, the lift system10can include a tube support slider65, as shown inFIG. 11. The tube support slider65may be positioned along the length16of the tube11to provide additional front-to-rear structural support to the tube11. For example, each of a plurality of the tube support sliders65may be positioned in between locations of the loft blocks32. The tube support slider65can be similar to the loft block slider33in design and operation. The tube support slider65can comprise a front slider arm58spaced apart from a rear slider arm60, and a support bar61on each end of the tube support slider65connecting the front and rear slider arms58,60, respectively. Each of the front and rear tube support slider arms58,60can include a groove62along the length of the slider arm58,60. The groove62can be adapted to slidingly engage a respective upper front rail or upper rear rail56along the length16of the tube11. By sliding the tube support slider groove62along the upper tube rails56, the tube support slider65can be positioned at a desired location along the length16of the tube11.

The tube support slider65can further include a locking mechanism64disposed on each of the front and rear slider arms58,60, respectively, for locking the tube support slider65in a desired position along the length16of the tube11. The tube support slider locking mechanism64can include the tab63located on each end of the front and rear slider arms58,60, respectively, and a biasing mechanism attached to each tab63. When the tabs63are depressed, the biasing mechanism is released and the tube support slider65can be slid along the front and rear tube rails56. When the tabs63are released, the biasing mechanism is actuated so as to lock the tube support slider65onto the front and rear tube rails56.

In certain embodiments, the loft block sliders33and the tube support sliders65can provide structural support to the compression tube11so as to help prevent the tube11from bowing outwardly in a perpendicular direction relative to the length16of the tube11. As horizontal stress is placed on the lift system10between the drive mechanism23and the loft blocks32by a load attached to the cables, the tube11may have a tendency to bow outwardly from front12to back13. Thus, the loft block sliders33and the tube support sliders65can help prevent the tube11from bowing outwardly in a perpendicular direction relative to the length16of the tube11.

Some embodiments of the lift assembly system10, for example, as shown inFIG. 11, can include a plurality of the tubes11arranged end-to-end. A plurality of the loft blocks32can be positioned along each of the modular tubes11, and one of a plurality of the elongate members31can be routed about each of the loft blocks32.

FIG. 11shows the plurality of elongate members31, or cables, coming from the drive mechanism23unattached in the bottom15of the tube11. In some embodiments, the plurality of cables11can be attached to the cable belt47,48, for example, as shown inFIG. 6. The cable belt47,48can have a width substantially equal to a width of the drum25, and can be windably attached to the drum25. As illustrated inFIG. 11, the head block39can include a series of channels59for aligning and directing each of a plurality of the cables31. The drum25and the first and second traction drives26,27, respectively, can also each include a plurality of channels59in their respective surfaces, each channel59being configured to align and direct one of a plurality of the cables31along its path. Certain embodiments of the head block39, as shown inFIG. 11, can include a bifurcated rotating surface such that the cables31can be spaced apart into two groups so as to provide a space in the center along the length16of the tube11for locating the loft blocks39.

As shown inFIGS. 11 and 12, an embodiment of the lift system10can further include a tube overhead connector66adapted to secure the tube11to the overhead structure87. The tube overhead connector66can include a front connector sleeve68and a rear connector sleeve69. Each connector sleeve68,69, can be slidably disposed on the top14and along the length16of the tube11. The tube overhead connector66can have two cooperating portions67slidable along the tube11away from and toward each other, and a securing mechanism to secure the cooperating portions67to each other and about the overhead structure87. The securing mechanism can be, for example, a biasing mechanism configured to push the cooperating portions67together, or a nut and bolt adapted to pull the cooperating portions67together. The cooperating portions67of each of the front and rear connector sleeves68,69, respectively, can be connected to each other with a connector rod75. The tube overhead connector66can further include a triangular-shaped cut-out72adapted to fit about a variety of thicknesses of the overhead structure87. For example, different I-beams used as roofing structural supports87can have varying shapes and thickness of the flanges of the I-beam. The triangular cut-outs72can accommodate such varying shapes and thickness so that a particular tube overhead connector66can be utilized with different I-beams.

The tube overhead connector66can be connected to a rail (not shown) on the top14and along the length16of the tube11. A block of material73can be fastened with one or more of the fasteners74to the inside surfaces of the front and rear legs70,71, respectively, of each of the front and rear connector sleeves68,69, respectively. The blocks of material73can be spaced apart such that the rail, for example, a T-shaped rail, on the top14of the tube11can fit between and rest on top of the blocks of material73. In this manner, the tube overhead connectors66can be slidably secured to the tube11. The tube overhead connector66can comprise various materials sufficiently strong to support the weight of the lift system10and associated loads. For example, the tube overhead connector66can be made of steel. The blocks of material73can comprise, for example, a nylon material that can help absorb sound between the contacting surfaces of the tube11and the tube overhead connector66.

In an embodiment in which each connector sleeve68,69is slidably disposed on the top14and along the length16of the compression tube11, the tube11can slide, or “float,” along the longitudinal axis, or length16of the tube11. That is, as horizontal stress is placed on the tube11by pressure on the cables31between the drive mechanism23and a load attached to the cables31, the compression tube11can absorb at least a portion of that horizontal stress by “compressing,” or moving slightly, for example, one to two inches, in the horizontal direction between the overhead support structures87to which it is attached. In such an embodiment, at least one tube overhead connector66can fix one point of contact on the tube11to an overhead support structure87, and one or more of the tube overhead connectors66can be slidably disposed on the tube11. In this manner, the compression tube11can compress horizontally and thereby absorb horizontal stress.

As shown inFIG. 13, an embodiment of the lift system10can further include a load-side braking mechanism36. Such a braking mechanism36can be connected to the elongate member31and movable within the tube11. The braking mechanism36can include a pair of brake cables76extending the length16of the tube11and secured to each end20,21of the tube11. A pair of spaced-apart plates77having grooves78in internal faces of the plates77can be configured for sliding about the pair of brake cables76. A brake assembly79disposed between the plates77can include a pivot structure80and a rocker arm81at the connection with the elongate member31. The rocker arm81can be urged along an angled rocker arm guide82into contact with one of the brake cables31. When tension on the elongate member31exerted by the drive mechanism36decreases below a preset threshold, the pivot structure80can pivot86so that the rocker arm81engages the brake cable76, thereby stopping movement of the elongate member31.

The brake assembly79can include a delay mechanism adapted to momentarily delay engagement of the brake cables76by the rocker arms81after tension on the elongate member31decreases below the threshold. As shown inFIG. 13, the pivot structure80can include a first pivot arm83and a second pivot arm84smaller than the first pivot arm83. The first and second pivot arms83,84, respectively, can be connected with a pair of pivot arm connectors85such that when the first pivot arm83pivots86in the elongate member's path of travel, the second pivot arm84is also pivoted86. The different sizes of the first and second pivot arms83,84, respectively, provides a mechanical advantage between the two pivot arms83,84such that a small decrease in tension on the elongate member31, for example, a momentary decrease in tension during start-up of the motor28, will not cause the rocker arms81to engage the brake cables76.

Some embodiments of the present invention can include a method for raising and lowering the article22in one or more directions utilizing the lift system10as described herein. For example, such a lift system10can comprise a substantially rectangular tube11; a rotatable drum25external to the tube11; a drive mechanism23structurally connected to one end20of the tube externally, and comprising a motor28rotatingly connected to a first traction drive26and operably connected to the drum25and to a second traction drive27; a head block39fixedly connected to an opposite end21of the tube11; and a loft block32spaced from the head block39and connected to the tube11internally. Some embodiments of such a method can include connecting the tube11to the overhead structure87. The method can further include routing the elongate member31attached on one end to the drum25through a generally horizontal path of travel from the drum25to the first and second traction drives,26,27, respectively, to the head block39, and to the loft block32, and then through a generally vertical path of travel downward from the loft block32. The method can further include attaching the end of the elongate member31opposite the drum25to the article22; winding the elongate member31about the drum25to raise the article; and unwinding the elongate member31from the drum25to lower the article22.

In some embodiments of a method, each of a plurality of the loft blocks32can be positioned at a different desired location selected from an infinite number of locations along a length16of the tube11. The tube11can further comprise a substantially rigid, compressible material, and such a method can include compressing the tube11with at least a portion of a horizontal load placed on the lift system10between the drive mechanism23and the loft block32. In certain embodiments, tension on the elongate member31can be controlled during winding and unwinding. For example, the drive mechanism23can include a tension clutch37connected to the drum25. Varying amounts of tension can be applied with the tension clutch37on the drum25to allow the drum25to rotate at varying speeds relative to the rotational speed of the first traction drive26, thereby controlling tension on the elongate member31during winding and unwinding.

In some embodiments of a method, movement of the article22can be altered, for example, slowed and/or stopped, with a load-side braking mechanism36connected to the elongate member31and movable within the tube11. In certain embodiments, the lift system10may include a plurality of each of the tubes11, the loft blocks32, and the elongate members31. The tubes11can be arranged in an end-to-end configuration, and one of the elongate members31, or cables, can be routed about each of the loft blocks32.

In some embodiments of a method, a sensor can be located relative to the article22attached to the elongate member(s)31to detect an obstruction in the path of travel of the article22. A signal can be transmitted from the sensor to a controller in response to detecting the obstruction. Movement of the article22can then be altered in response to the transmitted signal. In certain embodiments, movement of the elongate member31and the attached article22can be controlled with a programmable controller, such as a computer49. In particular embodiments, the lift system10can be controlled with a remote control device.

Some embodiments of the present invention may be utilized in applications other than those described herein. For example, certain embodiments of a lift system10of the present invention can be configured for operably connecting to an existing counterweight system. In such an embodiment, the lift system10can cooperate with existing counterweights. For example, the drive mechanism23can actuate the counterweights in coordination with movement of the cables31.

Some embodiments of the present invention can be utilized to move articles or loads other than those related to performing arts and in settings other than a performing arts stage. An embodiment of the lift system10can be used in any setting in which there is a desire to move articles or loads, particularly in an upward and downward fashion, in a controlled manner. For example, certain embodiments of a lift assembly system10may be utilized to move manufacturing equipment in an industrial setting, to change advertising displays in a retail setting, or to coordinate movement of overhead equipment in a hospital operating room.

Features of a lift assembly, system, and method of the present invention may be accomplished singularly, or in combination, in one or more of the embodiments of the present invention. Although particular embodiments have been described, it should be recognized that these embodiments are merely illustrative of the principles of the present invention. Those of ordinary skill in the art will appreciate that a lift assembly, system, and method of the present invention may be constructed and implemented in other ways and embodiments. Accordingly, the description herein should not be read as limiting the present invention, as other embodiments also fall within the scope of the present invention.