Patent Publication Number: US-2012025157-A1

Title: Lift assembly, system, and method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 12/856,873, filed Aug. 16, 2010, which is a continuation of U.S. patent application Ser. No. 11/796,781, filed Apr. 30, 2007, which claimed the benefit of U.S. Provisional Patent Application No. 60/873,389, filed Dec. 7, 2006, and U.S. Provisional Patent Application No. 60/796,362, filed on Apr. 28, 2006, the entire contents of which are incorporated by reference herein in their entirety. 
    
    
     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 
     The present invention provides a lift assembly comprising a plurality of elongate members (e.g., cables) positioned for movement in a longitudinal direction, a drive mechanism (e.g., a drum) coupled to move the elongate members in the longitudinal direction, and a loft block including a sheave located to redirect at least one of the elongate members to a non-parallel path that is not parallel to the longitudinal direction, wherein a remainder of the elongate members travel along a parallel path that is above the sheave. In one embodiment the loft block includes an idler bar having an upper surface that is higher than an upper surface of the sheave. For example, in one embodiment, the idler bar is positioned directly above the sheave. Preferably, the lift assembly further comprises a second loft block including a second sheave located to redirect at least one of the remainder of the elongated members to a second non-parallel path that is not parallel to the longitudinal direction, wherein a second remainder of the elongated members travel along a second parallel path that is above the second sheave. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view of a lift assembly system in an embodiment of the present invention. 
         FIG. 2  is a view of a lift assembly system showing a drive mechanism and a partially cut-away view of a portion of a compression tube and the components inside the tube in an embodiment of the present invention. 
         FIG. 3  is a close-up view of the drive mechanism shown in the lift assembly system in  FIG. 2 . 
         FIG. 4  is another close-up view of the drive mechanism shown in the lift assembly system in  FIG. 2 . 
         FIG. 5  is another close-up view of the drive mechanism shown in the lift assembly system in  FIG. 2 . 
         FIG. 6  is a view of a lift assembly system having two drums and two cable belts in another embodiment of the present invention. A portion of the tube has been removed to show components inside the tube. 
         FIG. 7  is a perspective view of a cable connector in an embodiment of the present invention. 
         FIG. 8  is a perspective view of a portion of the cable connector shown in  FIG. 7 . 
         FIG. 9  is a perspective view of another portion of the cable connector shown in  FIG. 7 . 
         FIG. 10  is a view of a computer controller useful in an embodiment of the present invention. 
         FIG. 11  is a perspective view of the head block end of a lift assembly system having the front half of the compression tube removed to show the internal components in an embodiment of the present invention. 
         FIG. 12  is a close-up perspective view of the tube overhead connector shown in the embodiment in  FIG. 11 . 
         FIG. 13  is a view of a braking mechanism having one plate removed to show the internal components in an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Some embodiments of the present invention can provide a lift assembly, system, and/or method.  FIGS. 1-13  show various aspects of such embodiments. An illustrative embodiment of a lift assembly system  10  can include a coiling apparatus, or drum  25 , a first traction drive  26  operably connected to a drive mechanism  23 , a second traction drive  27 , a tube  11  containing one or more pulleys, for example, a head block  39  and loft blocks  32 , and one or more elongate members  31 , such as cables. The cables  31  can be attached to the drum  25  and configured to travel in a generally horizontal path from the drum  25  around the second traction drive  27  to and around the first traction drive  26  to the head block  39  and the loft blocks  32  inside the tube  11 . From the loft blocks  32 , the cables  31  can travel in a generally vertical path, that is, upward and downward between the loft blocks  32  and a surface below. An article  22 , or load, can be attached to the cables  31  such that when the cables  31  are moved in the generally vertical path, the attached article  22  can 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 articles  22 , 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 articles  22  and loads other than theatrical stage equipment. 
     In certain instances, the articles  22  to 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 member  31 , 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 assembly  10  is 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. 
     Drum 
     In some embodiments of the present invention, the lift assembly system  10  can include a coiling apparatus, or drum  25 , as shown in  FIGS. 2-4 . One end of the elongate members  31 , or cables, can be securely attached to the drum  25 . The drum  25  can include a series of channels  59  or contoured surface areas about which the cables  31  can be coiled, or wound, and from which the cables  31  can be uncoiled, or unwound. In some embodiments, the drum  25  can include a channel  59  or contoured surface area for each cable  31  to be wound and unwound. For example, as shown in  FIGS. 3 and 11 , the drum  25  can include eight cable-receiving channels  59 . Each channel  59  or contoured surface area can be sized to retain a length of cable  31  sufficient to dispose the article  22  connected to the cable  31  between a fully lowered position and a fully raised position. Alternatively, the drum  25  can have a smooth surface about which the cables  31  can be wound and from which the cables  31  can be unwound in a side-by-side manner. 
     The drum  25  may be rotatably connected to a the tube  11  and operably connected to the motor driveshaft  29  with a linking element, such as a belt, chain, or other linking mechanism. As shown in  FIG. 3 , the drum  25  can be operably connected to the first traction drive  26  with a drum drive belt  34 . 
     Traction Drives 
     In some embodiments of the present invention, the lift assembly system  10  can include one or more traction drives  26 ,  27 . The fraction drives  26 ,  27  can be rotatable such that elongate members  31  such as cables can move about the rotating surfaces of the traction drives  26 ,  27 . The traction drives  26 ,  27  can include a series of channels  59  or contoured surface areas, similar to the channels  59  or contoured surface areas in the drum  25 , about which the cables  31  can travel. The fraction drives  26 ,  27  can 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 in  FIGS. 2-5 , an embodiment of the lift assembly  10  can include two traction drives  26 ,  27  that are operably linked with each other and with the drum  25  with one or more chains, belts, or other linking mechanisms. For example, as shown in  FIG. 3 , the drum drive belt  34  can operably connect the first fraction drive  26  and the drum  25  so that rotation of the first traction drive  26  causes corresponding rotation of the drum  25  in the same direction. A second traction drive belt  35  can operably connect the first traction drive  26  and the second traction drive  27  so that rotation of the first traction drive  26  causes corresponding rotation of the second traction drive  27  in the same direction. As such, the drum  25  and first and second traction drives  26 ,  27 , respectively, can move together in a coordinated, simultaneous fashion so as to provide synchronous movement of the cables  31 . 
     In certain embodiments, the traction drives  26 ,  27  can be positioned relative to each other and to the path of travel of the cables  31  such that the traction drives  26 ,  27  place tension on the cables  31  and thereby help to maintain the cables  31  in a desired position as the cables  31  travel along a path. For example, as shown in  FIGS. 2 and 3 , the first traction drive  26  can be positioned between the drum  25  and the tube  11  and the second traction drive  27  can be positioned between the first traction drive  26  and the tube  11 , such that the cable  31  can extend along a generally horizontal path from the drum  25  to and about the second traction drive  27 , to and about the first traction drive  26 , and then to the head block  39 . Alternatively, as shown in  FIGS. 4 and 5 , the first traction drive  26  can be positioned between the drum  25  and the tube  11  and the second traction drive  27  can be positioned between the drum  25  and the first traction drive  26 , such that the cable  31  can extend along a generally horizontal path from the drum  25  to and about the first traction drive  26 , to and about the second traction drive  27 , and then to the head block  39 . As a result, the traction drives  26 ,  27  can serve to keep the cables  31  in aligned positions as they travel from the drum  25  to the head block  39  and/or loft blocks  32 . The use of two cooperating traction drives  26 ,  27  can increase the lifting (torque) capacity on the cables  31 , thereby increasing the load capacity of the lift system  10 . As a result, the ability of the lift assembly system  10  to safely support and move a load can be increased. 
     Drive Mechanism 
     In some embodiments of the present invention, the lift assembly system  10  can include a drive mechanism  23 . The drive mechanism  23  may include a motor  28 , for example, an electric motor  28 . The drive mechanism  23  may further include a set of gears (not shown), which may be housed in a gear box  30 , for transferring rotational motion of the motor  28  to the drive shaft  29  and in turn to the first traction drive  26 . The drive mechanism  23  can be housed in a drive mechanism housing  24 , as shown in  FIG. 1 . The motor  28  can cause rotation of the first traction drive  26  about its rotational axis. In embodiments in which the second fraction drive  27  and the drum  25  are operably linked to the first traction drive  26 , the motor  28  and gears can likewise cause rotation of the second traction drive  27  and the drum  25 . The motor  28  may 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 box  30  can rotate the drive shaft  29 , and the traction drives  26 ,  27  and drum  25 , 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 motor  28 . The gears may provide a speed-reducing mechanism to reduce the rotational speed of the motor  28  to an output speed of the drive shaft  29  that is suitable for rotating the traction drives  26 ,  27  and drum  25 . 
     The first traction drive  26  and the drum  25  can be operably connected with the drum drive belt  34 , as described. In some embodiments, the first traction drive  26  and the drum  25  can rotate at predetermined relative speeds, or rates. When cables  31  are wound about the drum  25  such that the article  22  attached to the cables  31  is moved to its uppermost position, the cable lengths about the drum  25  create a circumference of the combined drum  25  and cables  31  that is greater than the circumference of the drum  25  alone. Thus, in certain embodiments, as the motor  28  rotates the first traction drive  26  at a first speed, due to the larger drum-cable circumference, the drum  25  can be rotated initially at a second, lower speed relative to the first rotational speed of the first traction drive  26 . During an unwinding operation, the first traction drive  26  can rotate constantly at the first speed. Due to the progressively smaller drum-cable circumference during unwinding, the drum  25  can be rotated at increasing speeds relative to the initially lower second speed of the drum  25 , in order for the cable  31  to move about the first fraction drive  26  at the same rate as it unwinds from the drum  25 . Unwinding the cables  31  from the drum  25  and about the first traction drive  26  at the same rate helps maintain a constant tension on the cables  31 . 
     Likewise, when the cables  31  are unwound from the drum  25  such that the article  22  attached to the cables  31  is moved to its lowermost position, the cable lengths about the drum  25  create a circumference of the combined drum  25  and cables  31  that is greater than the circumference of the drum  25  alone but less than the drum-cable circumference when the cables  31  are fully wound about the drum  25 . During a winding operation, the first traction drive  26  can rotate constantly at the first speed, and the drum  25  can rotate initially at the same first speed as that of the first fraction drive  26 . Due to the progressively larger drum-cable circumference during winding, the drum  25  can be rotated at decreasing speeds relative to the first speed in order for the cable  31  to move about the first traction drive  26  and wind about the drum  25  at the same rate. Winding the cables  31  about the first traction drive  26  and onto the drum  25  at the same rate helps maintain a constant tension on the cables  31 . 
     In some embodiments, the drive mechanism  23  can include a tension clutch  37 , as shown in  FIG. 3 . The tension clutch  37  can allow the drum  25  to rotate at a different speed relative to the rotational speed of the first traction drive  26  so as to accommodate the variable drum-cable circumference related to the amount of cable  31  wound about the drum  25  at particular times during winding and unwinding of the cables  31 . For example, as the cables  31  are unwound from the drum  25  and the drum-cable circumference becomes smaller, the tension clutch  37  can decrease tension on the drum  25  so as to allow the drum rotational speed to increase relative to the initially lower second rotational speed of the drum  25 . As the cables  31  are wound about the drum  25  and the drum-cable circumference becomes larger, the tension clutch  37  can increase tension on the drum  25  so as to allow the drum rotational speed to decrease relative to the constant speed of the first traction drive  26 . In this manner, the cables  31  can be wound about and unwound from the drum  25  and about the first traction drive  26  at the same rate so as to maintain a constant tension on the cables  31 . 
     The drive mechanism  23  arrangement can provide for control of the tension and movement of the cables  31 . As such, the drive mechanism  23  can provide the advantage of allowing some embodiments of the lift assembly system  10  to be utilized without the use of counterweights. In some embodiments, the drive mechanism  23 , and thereby the lift system  10 , can be controlled in an automated manner, for example, by a computer  49 . In certain embodiments, the drive mechanism motor  28  may be actuated by a remote control device (not shown). 
     In some embodiments, as shown in  FIG. 3 , a pressure roller  19  can be positioned adjacent each of the first and second traction drives  26 ,  27 , respectively, to maintain a consistent pressure on each cable  31  routing about the traction drives  26 ,  27 . For example, the pressure roller  19  can be positioned above each of the first and second traction drives  26 ,  27 , respectively, and configured to apply positive, downward pressure on each cable  31  at the point in the cable&#39;s  31  path of travel in which it contacts the particular traction drive  26  or  27 . In some situations a load attached to the cables  31  may be unevenly distributed across a plurality of cables  31  to which the load is attached. As a result, the cables  31  can be more tightly wound onto one portion of the rotating surface of the traction drives  26 ,  27  than onto another portion. For example, cables  31  having a heavier load portion can sink into the channels  59  in the traction drives  26 ,  27  more deeply as they are wound about the traction drives  26 ,  27  than cables  31  having a relatively lighter load portion. As uneven load pressure can cause one or more cables  31  to sink into the channel(s)  59  unevenly, the various loft block  32 —cable  31  diameters 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)  19  on each of the cables  31  as they route about the traction drive(s)  26 ,  27 , evenly distributed pressure on cables  31  as they route about rotating surface of the traction drive(s)  26 ,  27  can 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 mechanism  23  may include the pressure roller  19  in operative contact with the first traction drive  26 , with the second traction drive  27 , or with each of the traction drives  26 ,  27 . The pressure roller(s)  19  may be fixed in position at a predetermined distance from the traction drives  26 ,  27 . Alternatively, the pressure roller(s)  19  may be configured so as to be movable from one distance from the traction drive(s)  26 ,  27  to another distance from the traction drive(s)  26 ,  27 . In this manner, the pressure roller(s)  19  can be adjusted to accommodate various cable diameters and/or various loads. 
     In some embodiments, the drive mechanism  23  can be located completely external to the tube  11  containing the loft blocks  32 . Some embodiments of the lift assembly  10  can be equipped with different sizes and capacities of motors  28 . As an example, a five horsepower electric motor  28  can be exchanged for a 10 horsepower motor  28  or a 15 horsepower motor  28  when greater power is desired for moving heavier objects. 
     As shown in  FIG. 1 , the lift assembly  10  can include a cover or housing  24  for the drum  25 , first and second traction drives  26 ,  27 , respectively, and other drive mechanism  23  components. 
     Elongate Members 
     Some embodiments of the lift assembly system  10  can be constructed to cooperate with at least one elongate member  31 , such as a cable, or other length of material, connected at one end to the drum  25  and at the other end to the article  22  or load to be moved. In some embodiments, the number of cables  31  can be at as many as eight or more cables  31 . 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 cables  31  can have various constructions and dimensions suitable for fitting about the drum  25 , traction drives  26 ,  27 , head block  39 , and loft blocks  32  and for supporting loads attached to the cables  31 . For example, the cables  31  can have multiple strands twisted together to provide increased tensile strength. In some embodiments, the cables  31  can have a diameter larger than the 3/16 inch diameter cables  31  used in conventional lift assemblies. For example, certain embodiments of a lift assembly system  10  of the present invention can accommodate a cable  31  having 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 cable  31  may have a 3/16 inch diameter or smaller. 
     A length of cable  31  can be disposed about each channel  59  in the drum  25  sufficient to wind about the first and second traction drives,  26 ,  27 , respectively, to extend horizontally to the head block  39  and to the loft block  32  around which it moves, and then downward to the point at which it is connected to the article  22  or load. The cable  31  can have a length sufficient to fully lower a desired article  22  or load. In some embodiments, each loft block  32  can be positioned at different intervals along the length  16  of the tube  11 , and thus at a different distance from the drum  25 . As a result, the cable  31  that is routed about each loft block  32  may be a different length than each other cable  31 . 
     Compression Tube 
     In another aspect of the present invention, some embodiments of the lift assembly system  10  can include the compression tube  11  as shown in  FIGS. 1 ,  2 ,  5 ,  7 , and  11 . The compression tube  11  can comprise a length of substantially rigid material that can be connected to an overhead building structure  87 . As shown in  FIG. 2 , the compression tube  11  can include a plurality of loft blocks  32 , or pulleys, disposed at intervals along the inside length  16  of the tube  11 . Each loft block  32  can rotatingly engage one or more cables  31 . The loft blocks  32  can re-direct the generally horizontal path of the cables  31  from the drum  25  and traction drives  26 ,  27  to a generally vertical path to the attached article(s) below the compression tube  11 . 
     Depending upon several factors, including, for example, the dimensions and weight of the article  22  to be raised and/or lowered, the number of loft blocks  32  utilized in an embodiment of the present invention can vary. In some embodiments, for example, the lift assembly system  10  can include eight loft blocks  32  and thus eight cable drop points, as compared to some conventional lift assemblies which provide seven or fewer loft blocks  32 , thus providing greater support to the article  22  and greater flexibility as to locations on the article  22  to which the cables  31  can be attached. 
     In some embodiments, the loft blocks  32  can be secured at an infinite number of locations along the longitudinal continuum, or length  16 , of the compression tube  11 , thus providing flexibility as to locations on the article  22  to which the cables  31  can be attached. In some embodiments, each loft block  32  can be connected to a loft block slider  33  having a locking mechanism  64 . The loft block sliders  33  and connected loft blocks  32  can be moved for positioning at a particular location along the length  16  of the compression tube  11 . In certain embodiments, the compression tube  11  can include a means for engaging the loft blocks  32 . For example, the means for engaging the loft blocks  32  can include a rail  57  extending outwardly into the interior of the tube  11 . Each of the loft block sliders  33  can have a groove  62  along its length adopted to slidingly engage the tube rail  57 . Alternatively, the means for engaging the loft blocks  32  can include a channel in the length  16  of the opposing walls of the tube  11 . Each of the loft block sliders  33  can have an arm extending outwardly from each side of the loft block sliders  33  that can slidingly engage the channels along the tube  11 . In such configurations, the loft block sliders  33  and connected loft blocks  32  can be positioned at a substantially infinite number of locations along the length  16  of the tube  11 . Once the loft block  32  is in a desired position along the length  16  of the tube  11 , the locking mechanism  64  can be actuated to secure the loft block  32  in that position. 
     In some embodiments, the lift system  10  can include the head block  39  secured within the compression tube  11 . In certain embodiments, the head block  39  can be secured at the head block end  21  of the tube  11  opposite the drive end  20  to which the drive mechanism  23  is attached. The head block  39  can be located to redirect the elongate member  31 , or cable, from a first generally horizontal path from the drive mechanism  23  to a second generally horizontal path to the loft blocks  32  back in the direction of the drive mechanism  23 . The head block  39  can include channels  59  for aligning and directing each of a plurality of the cables  31 . As shown in  FIG. 11 , certain embodiments of the head block  39  can include a bifurcated rotating surface such that the cables  31  can be spaced apart into two groups so as to provide a space in the center along the length  16  of the tube  11  for locating the loft blocks  32 . In such a configuration, one of the centermost cables  31  on one side of the bifurcated head block  39  can be routed to the loft block  32  nearest to the head block  39 , so as to decrease the fleet angle of the cable  31  between the head block  39  and the loft block  32 . The other centermost cable  31  (on the other side of the bifurcated head block  39 ) can be routed to the loft block  32  second nearest to the head block  39 . The other cables  31  can then be alternatingly routed to loft blocks  32  subsequently farther from the head block  39 . Such a configuration can provide for optimal fleet angles of the cables  31  and an even distribution of the load attached to the cables  31 . 
     The compression tube  11  can include an opening  17  in the bottom  15  of the tube  11  along at least a portion of the length  16  of the tube  11 . The cables  31  that are routed about the loft blocks  32  can be routed downward through the opening  17  for movement upward and downward to raise and lower the attached article  22 . 
     In some embodiments, for example, as shown in  FIGS. 1 and 12 , the compression tube  11  can include a connecting mechanism disposed on the top  14  of the tube  11  for connecting the tube  11  to an overhead structure  87 , such as a building support beam. The connecting mechanism can comprise connector arms  18  that 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 structure  87 . For example, the tightening mechanism can include a threaded rod threaded through openings in each of the connector arms  18  that can be rotated so as to move the arms  18  closer to each other and about the overhead structure  87 .  FIG. 12  illustrates another embodiment of a tube overhead connector mechanism, described herein. The tube  11  may be connected to the overhead support structure  87  in other manners and utilizing other connecting mechanisms. 
     Some embodiments of the lift assembly system  10  can include a single primary compression tube  11  unit having a predetermined length. Such a primary compression tube  11  unit 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 tubes  11  can 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 system  10  can include a primary compression tube  11  unit and one or more extension units of the compression tube  11 . In such embodiments, the extension tube  11  unit(s) can include a desired number of loft blocks  32 , and can be installed end-to-end with the primary tube  11  unit to provide a length of compression tube  11  having various desired lengths. In this arrangement, the lift assembly system  10  can include a single drive mechanism  23  at one end of the primary tube  11  unit. The cables  31  to be routed through the bottom  15  of the extension tube  11  unit can be routed from the single drive mechanism  23  on the drive end  20  of the primary tube  11  through the opposite end of the primary tube  11 , to the head block  39 , if included, and to the loft blocks  32  in the extension tube  11 . In this manner, the lift assembly system  10  can include various lengths of the compression tube  11  and various numbers of the loft blocks  32  for routing a corresponding number of the cables  31  to the article  22  to be moved. For example, one compression tube  11  may include eight loft blocks  32 , and two end-to-end compression tubes  11  may contain 16 loft blocks  32 . The compression tube  11  and/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 tubes  11  and/or extensions can be manufactured in customized lengths. 
     The compression tube  11  can be made in various manners. In one embodiment, the tube  11  can be extruded using a material such as aluminum, steel, an alloy, or other material. The compression tube  11  can comprise any material that is sufficiently strong to support the components contained inside the tube  11  and the load placed on the loft blocks  32  from the article  22  attached to the cables  31 . In some embodiments, the material can be a lightweight material so as to reduce the overall weight of the lift assembly system  10 . In other embodiments, the compression tube  11  can be molded from such materials. 
     In another aspect of the present invention, the configuration of the compression tube  11  in combination with the drive mechanism  23  can decrease or eliminate substantially all of the horizontal load stress on a ceiling and/or roof structure to which the lift assembly system  10  is mounted. In conventional lift systems, the drive mechanism  23  and the loft blocks  32  are often mounted to physically separate structures in a building, for example, different overhead beams. As a result, a load being moved by the cables  31  can place a horizontal stress between the overhead structural building supports to which the drive mechanism  23  is attached and the supports to which the loft blocks  32  are 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 in  FIG. 1 , the compression tube  11  (to which the loft blocks  32  are attached) and the drive mechanism  23  can be physically, or structurally, connected or integrated, for example, by welding or otherwise fastening together. In this manner, the horizontal stress between the drive mechanism  23  and the loft blocks  32  can be absorbed by the structure of the lift assembly  10 , rather than being displaced onto building support structures to which separate components of the lift assembly  10  are attached. 
     In some embodiments, the compression tube  11  can be constructed of a substantially rigid material, for example, aluminum, steel, an alloy, or other material. The tube  11  may be adapted to absorb some of the horizontal load placed on the attached loft blocks  32 , by sliding, or “floating,” along the longitudinal axis, or length  16  of the tube  11 . As horizontal stress is placed on the tube  11  by pressure on the cables  31  between the drive mechanism  23  and a load attached to the cables  31 , the compression tube  11  can 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 structures  87  to which it is attached. As described herein, the tube  11  may be fixedly attached at one point of contact on the tube  11  to one overhead support structure  87 , 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 tube  11  can 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 system  10  of the present invention. 
     A plurality of the compression tubes  11  containing a plurality of the loft blocks  32  and the cables  31  can be engaged with multiple overhead support structures  87  such that adjacent compression tubes  11  abut each other along a longitudinal dimension. As a result, multiple compression tubes  11  installed in an abutting relation can contact each other and cooperate to absorb, and thus decrease, the horizontal load on the overhead structure  87 , thereby reducing any relative movement between the overhead structures  87 . 
     In certain embodiments, the lift assembly system  10  can be supported as a free-standing unit. As an example, the lift assembly system  10  can be supported on each end  20 ,  21  with 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 system  10  can be used in settings without the need for an overhead support structure  87  such as the roof of a building. 
     Cable Belt 
     In an alternative embodiment, as shown in  FIG. 6 , the lift assembly system  10  can include a first drum  45  and a second drum  46  (or bifurcated portions of the drum  25 ), each drum  45 ,  46  being axially aligned with and operably connected to the drive shaft  29  of the drive mechanism  23 . A first cable belt  47  can be attached to the first drum  45 , and a second cable belt  48  can be attached to the second drum  46 . The first and second cable belts  47 ,  48 , respectively, can comprise various materials, for example, a windable steel tape. The cable belts  47 ,  48  can be wound about and unwound from the respective drums  45 ,  46 . The cable belts  47 ,  48 , or tapes, can each have a width corresponding to the width of a plurality of cables  31 . A plurality of the cables  31 , for example, eight cables  31 , can be attached to the distal end of each of the first and second cable belts  47 ,  48 , respectively. A plurality of cables  31  can be attached to the respective cable belts  47 ,  48  in various manners. One example of a means for connecting the cables  31  to the cable belts  47 ,  48  is the cable connector  38 , as shown in  FIGS. 7-9 . 
     In such an embodiment, the head block  39  can be positioned inside the head block end  21  of the compression tube  11  opposite the drive mechanism  23 . The first and second cable belts  47 ,  48 , respectively, can move through at least a portion of the length  16  of the compression tube  11  to near the head block  39 . Each of the individual cables  31  can be routed around the head block  39  and then to one of the loft blocks  32  along the length  16  of the compression tube  11 . 
     Braking Mechanism 
     In another aspect of the present invention, some embodiments of the lift assembly system  10  may include a braking mechanism  36 . The braking mechanism  36  can be an overspeed braking system. As shown in  FIGS. 2 and 3 , the brake  36  can be a “load-side” overspeed brake. That is, the brake  36  can be attached to a lift assembly  10  component other than the motor  28 . In this configuration, should the motor  28  and/or gears controlling speed of cable movement fail, the lift assembly system  10  can provide a braking mechanism  36  separate from operation of the drive mechanism  23  for preventing free fall of a load attached to the cables  31 . In this manner, the load-side brake  36  can provide redundancy relative to the power-train components for controlling downward movement, for example, slowing or stopping, of a load attached to the cables  31 . 
     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 mechanism  36  as 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 mechanism  36  can 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 mechanism  36  can comprise a flexible arm (not shown), such as a piece of flexible steel or aluminum, connected to the cables  31 . The flexible arm can be similar to a pawl-type arm. Tension on the cables  31  from an attached load can bias the flexible arm toward the bottom  15  or a side  12 ,  13  of the compression tube  11 . When tension on the cables  31  is 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 tube  11 , such as the top  14  of the tube  11  or the side  12 ,  13  of the tube  11  opposite the biased position of the flexible arm. The top  14  or side  12 ,  13  of the compression tube  11  interior 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 cables  31  attached to the flexible arm can be engaged with a surface in the interior of the compression tube  11  and thereby stop free-fall of the cables  31  and attached load. In an embodiment, a shock absorbing material can be placed between the arm-engaging surface and the interior surface of the compression tube  11  to help reduce undesirable stress on the tube  11  in the event that the flexible arm suddenly engages the arm-engaging surface during a free-fall of a load attached to the cables  31 . 
     In another embodiment, the load-side braking mechanism  36  can be connected to the elongate member  31 , for example, between a cable belt  47 ,  48  and a plurality of cables  31 , and movable within the tube  11 . As shown in the embodiment in  FIG. 12 , the braking mechanism  36  can include a pair of brake cables  76  extending the length  16  of the tube  11  and secured to each end of the tube  11 . A pair of spaced-apart plates  77  having grooves  78  in internal faces of the plates  77  can be configured for sliding about the pair of brake cables  76 . A brake assembly  79  disposed between the plates  77  can comprise a pivot structure  80  and a rocker arm  81  at the connection with the elongate member  31 . When tension on the elongate member  31  exerted by the drive mechanism  23  decreases below a preset threshold, the pivot structure  80  can pivot  86  so that the rocker arm  81  engages the brake cables  76 , thereby stopping movement of the elongate member  31 . 
     In another embodiment of a braking mechanism  36 , a braking member (not shown) can be attached to the outside of each of the outer cables in a plurality of the cables  31 . The two braking members can be attached to the cables  31  such that the braking members are held in place at a distance from the sides of the compression tube  11  with the tension on the cables  31  exerted 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 length  16 , of the tube  11 . When load-induced tension on the cables  31  is released, such as during the free-fall of the cables  31  and attached load, the braking members can move apart and into braking contact with the sides  12 ,  13  of the compression tube  11 . The sides  12 ,  13  of the compression tube  11  and/or the sides of the braking members facing the sides  12 ,  13  of the tube  11  can 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 sides  12 ,  13  of the tube  11 . In this way, the cables  31  attached to the braking members can be engaged with a surface in the interior of the compression tube  11  and thereby stop free-fall of the cables  31  and attached load. 
     In another embodiment of the lift assembly system  10 , the braking mechanism  36  can include the cable connector  38 . For example, as shown in  FIGS. 7-9 , the cable connector  38  can include two portions, a first portion (or male portion)  40  which fits within at least a part of a second portion (female portion)  41 . The two portions  40 ,  41  of the cable connector  38  can be secured to each other with a fastener  42 , for example, a screw, through overlapping portions of the male and female portions  40 ,  41 , respectively, of the connector  38 . The two portions  40 ,  41  of the cable connector  38  can be fastened together such that each portion can swivel, or pivot, within a limited span relative to the other portion  40 ,  41 . The male portion  40  can include a peg  43  extending perpendicularly through an arcuate opening  44  in the female portion  41 . The combination of the peg  43  and arcuate opening  44  can serve to limit the extent of pivoting, or swiveling, between the male and female portions  40 ,  41 , respectively, of the connector  38 . The cable connector  38  can be referred to as a “clew.” 
     The cable connector  38 , or “clew,” can be adapted to be inserted in the lengths of the cables  31  such that the cable connector  38  can connect one end of a plurality of the cables  31  to another end of the plurality of the cables  31 . That is, each of the cables  31  can be divided, or cut, into two separate portions. Each of the divided ends of the cables  31  can be secured to one of the portions of the cable connector  38 . The cable connector  38  can travel along the path of travel of the cables  31  within the compression tube  11 . In the event that one of the plurality of cables  31  experiences a loss of tension due to, for example, becoming disconnected from a load or from breaking, the lateral tension on the cable connector  38  from the remaining cables  31  can cause the cable connector portions  40 ,  41  to pivot, or swivel, relative to each other. When the cable connector portions  40 ,  41  swivel to one side, the side of the cable connector  38  can contact the side  12 ,  13  of the compression tube  11 . In this way, movement of the cables  31  and attached load can be slowed so as to prevent undesired downward movement of the load. In certain embodiments, the sides of the cable connector  38  and/or the sides  12 ,  13  of the compression tube  11  can include a brake pad type of material to provide a friction interface for slowing and/or stopping the cables when the cable connector  38  contacts the side  12 ,  13  of the tube  11 . 
     Sensor 
     In another aspect of the present invention, some embodiments of the lift assembly system  10  can include a safety mechanism for slowing and/or stopping downward movement of the cables  31  and attached article(s)  22  upon 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 motor  28  can be adapted to alter movement, for example, interrupt, stop, and/or reverse movement, of the cables  31 , 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 article  22  attached to the cables  31 , the sensor can detect the presence of the person and signal the motor  28  that an object is in the path of travel of the article  22 . The motor  28  can then interrupt, stop, and/or reverse movement of the cables  31 , and the attached article  22 . The motor  28  can be programmed so that once the object obstructing the article&#39;s path of movement is removed from the path of movement, for example, when a person moves from underneath the descending article  22 , the motor  28  can be automatically actuated to resume downward movement of the article  22 . 
     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 article  22 , to a batten, or to one or more cables  31 . 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 computer  49 , by a wire or wireless connection. The signal sent by the sensor indicating an undesirable object or obstruction in the article&#39;s path of movement can be received by and processed by the computer  49 . Once the computer  49  processes the signal from the sensor, the computer  49  can send a signal to alter operation of the motor  28  in a predetermined manner, such as stopping rotation of the motor  28 . 
     Controller 
     In another aspect of the present invention, some embodiments of the lift assembly system  10  can include a controller for controlling the drive mechanism  23 , and thereby movement of the cables  31  and attached article  22  or load. The controller can be a dedicated device or, alternatively, can include software for running on a personal computer  49 , wherein control signals are generated for the lift assembly  10 . 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 cables  31  and attached article(s)  22  to 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)  31  and/or attached article(s)  22  to determine the distance a particular point along the length of the cable  31  and/or article  22  is from the surface (such as a floor or the ground) below the cable  31  and/or article  22 . For example, one or more sensors can be placed on the ends of the cables  31  that can be adapted to sense the distance between the ends of the cables  31 , and thereby the bottom of the article  22 , and the floor below, and send a signal to the computer  49  indicating that distance. The computer  49  can be programmed to perform various operations in response to the cable end location signal. For example, the computer  49  can slow and/or stop movement of the cable  31  and attached article  22 , change orientation of the article  22  relative to the floor or other points of reference, reverse direction of movement of the article  22  at a predetermined time following receipt of the cable end location signal, as well as other operations. 
     Control of the lift assembly  10 , and particularly the drive mechanism  23  or motor  28  can be accomplished by a dedicated processor operably connected to the lift assembly system  10 . The processor can be operably connected to the drive mechanism  23 , and specifically the electric motor  28 , to control a variable speed of the motor  28 . The processor can be configured, or include code, to perform a number of functions, including, for example, control of the associated lift assembly  10 ; queuing functions; timing or duration of a particular drive state; controlling the motor  28  to 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 computer  49  processor may be configured to: (1) rotate the drum  25  at a first velocity in a first rotational direction; (2) rotate the drum  25  at a second velocity in a second, different rotational direction; (3) accelerate the drum  25  rotation in the first rotational direction; (4) accelerate the drum  25  rotation in the second rotational direction; (5) rotate the drum  25  a first amount in the first rotational direction; and/or (6) rotate the drum  25  a second amount in the second rotational direction. 
     In some embodiments, the computer  49 , for example as shown in  FIG. 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 computer  49  may be programmed to send a signal to the motor  28  to change the rate of movement of the cables  31  and attached article  22  at particular points along the path of movement. For example, in certain embodiments, the computer  49  may be programmed to decelerate downward movement of the cables  31  and attached article  22  when the article  22  reaches a predetermined distance from the surface below the article  22 . That is, the cables  31  and article  22  may be lowered toward the surface below at a first rate. When the article  22 , such as a stage curtain, reaches a particular distance from the stage floor below, for example, two feet above the stage floor, the computer  49  may signal the motor  28  to decelerate movement to a second, slower rate of descent until the bottom of the stage curtain reaches the stage floor. 
     In certain embodiments, the computer  49  may be programmed to change the direction and/or rate of movement of the cables  31  and attached article(s)  22  at particular intervals. The changes in direction and/or rate of movement of the article(s)  22  can be coordinated with an artistic performance. For example, the computer  49  can be programmed to actuate the motor  28  to 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 computer  49  can be programmed to actuate the motor  28  at a predetermined time to then move the sun scenery rapidly downward in the opposite direction to indicate the quickly approaching nightfall. Accordingly, the computer  49  can be programmed to actuate the motor  28  to move the cables  31  and attached article(s)  22  in various directions and rates of movement for dramatic effect. 
     In another embodiment, the computer  49  processor may be configured to rotate the drum  25  in a direction, amount, and velocity corresponding to the direction, amount, and velocity of rotation of a drum  25  in another lift assembly. That is, the controller/processor  49  can include the ability to communicate with one or more interconnected lift assemblies  10  and control coordination of the operation of each of those lift assemblies  10 . As examples, in particular theatrical productions, multiple lift assemblies  10  may 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 in  FIG. 10 , the controller can include a computer  49  and a computer video display  52  useful for operating a processor for controlling embodiments of the lift assembly system  10 . In some embodiments, a user interface can be provided to facilitate operation of the processor and the lift assembly  10  by a user. For example, the user interface can include a laptop computer, keyboard  50 , mouse  51 , touch screen, computer video display terminal  52 , 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 assembly  10  or multiple interconnected lift assemblies  10  of the present invention. 
     Assembly of Lift System 
     Some embodiments of a lift assembly system  10  of 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 system  10 . 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 tube  11  and drive mechanism housing  24 , embodiments of the lift assembly system  10  of 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 system  10  of 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 system  10  of the present invention can be packaged for shipping to a customer for quick and easy installation. That is, the lift assembly system  10  can be packaged having all components ready for operation upon mounting to the overhead support structure  87 . For example, the cables  31  can be pre-routed from the drum  25  around the two traction drives  26 ,  27  and around the head block  39  and the loft blocks  32  inside the compression tube  11 . Once the integrated compression tube-drive mechanism system is mounted to the overhead support structure  87 , the loft blocks  32  can be moved by hand (for example, by depressing the tabs  63  as shown in  FIG. 11 ) or with a small tool into desired positions along the length  16  of the tube  11 . Once in position, the loft blocks  32  can be securely fastened to the compression tube  11  and the cables  31  dropped through the longitudinal opening  17  in the tube  11  for attachment to the article  22 . Such a ready-to-operate installation avoids the need to route cables  31  through 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 assembly  10  of 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 assembly  10  of 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 assembly  10  of 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. 11-13  show illustrative embodiments of aspects of the present invention. In some embodiments, the lift assembly system  10  can include a substantially rectangular tube  11  having a front and a rear C-shaped portion connected together to form a front  12 , rear  13 , top  14 , and bottom  15  of the tube  11 . In  FIG. 11 , the top  14  and front  12  portions of the tube  11  have been removed to show the arrangement of components inside the tube  11 . The C-shaped portions of the tube  11  can be configured such that when the portions are connected together, the bottom  15  edges of the front and rear portions remain spaced apart, thereby providing the opening  17  in the bottom  15  along at least a portion of the length  16  of the tube  11 . The tube  11  can be connectable to the overhead structure  87 , such as a building support beam. 
     The lift system  10  can include the drum  25  positioned externally to the tube  11 , as shown in  FIGS. 2-5 . The drum  25  can be adapted to wind and unwind one or more elongate members  31 , such as cables, to raise and lower the article  22  attached to the elongate members  31 . The lift system  10  can further include the drive mechanism  23 , as shown in  FIGS. 2-5 , structurally connected to the drive end  20  of the tube  11  externally. The drive mechanism  23  can comprise the motor  28  rotatingly connected to the first traction drive  26  and operably connected to the drum  25  and to the second fraction drive  27 . In such a configuration, the elongate member  31  can extend along a first generally horizontal path from the drum  25  about the first and second traction drives  26 ,  27 , respectively, to the tube  11 . 
     The head block  39  can be fixedly connected to the head block end  21  of the tube  11  opposite the drive end  20 . The head block  39  can rotate about a head block axle  55 , which is supported on either side of the head block  39  in a head block axle support  54 . A head block mount  53  can be attached to and extend from the axle support  54  on each side of the head block  39 . The head block mount  53  can be rotated into alignment with a surface of the tube  11  and be fastened to the tube  11  so as to secure the head block  39  to the tube  11 . The head block  39  can be located to redirect the elongate member  31  from the first generally horizontal path to a second generally horizontal path from the head block  39  back toward the drive mechanism  23 . 
     The loft block  32  can be spaced from the head block  39  and connected to the tube  11  internally. The loft block  32  can be located to redirect the elongate member  31  from the second generally horizontal path to a generally vertical path through the bottom opening  17  in the tube  11  to the attached article  22 . In some embodiments, the lift system  10  can include a plurality of the loft blocks  32 . Each loft block  32  can be positioned at an infinite number of locations on the continuum along the length  16  of the tube  11 . 
     The loft block  32  can further include the loft block slider  33  adapted to position the loft block  32  at a desired location along the length  16  of the tube  11 . The loft block slider  33  can comprise a front slider arm  58  spaced apart from a rear slider arm  60 , and a support bar  61  on each end of the loft block slider  33  connecting the front and rear slider arms  58 ,  60 , respectively. A loft block axle (not shown) can be supported on one end by the front slider arm  58  and on the opposite end by the rear slider arm  60 . The loft block  32  can be rotatingly attached about the loft block axle. Each of the front and rear loft block slider arms  58 ,  60 , respectively, can include a groove  62  along the length  16  of the slider arm  58 ,  60 . The groove  62  an be adapted to slidingly engage a respective lower front rail or lower rear rail  57  along the length  16  of the tube  11 . By sliding the loft block slider groove  62  along the lower tube rails  57 , the loft block  32  can be positioned at a desired location along the length  16  of the tube  11 . 
     The loft block slider  33  can further include a locking mechanism  64  disposed on each of the front and rear slider arms  58 ,  60 , respectively, for locking the loft block in a desired position along the length  16  of the tube  11 . In the embodiment shown in  FIG. 11 , the loft block slider locking mechanism  64  can include a tab  63  located on each end of the front and rear slider arms  58 ,  60 , respectively, and a biasing mechanism attached to each tab  63 . When the tabs  63  are depressed, the biasing mechanism is released and the loft block slider  33  can be slid along the front and rear tube rails  57 . When the tabs  63  are released, the biasing mechanism is actuated so as to lock the loft block  32  onto the front and rear tube rails  57 . 
     In some embodiments, the lift system  10  can include a tube support slider  65 , as shown in  FIG. 11 . The tube support slider  65  may be positioned along the length  16  of the tube  11  to provide additional front-to-rear structural support to the tube  11 . For example, each of a plurality of the tube support sliders  65  may be positioned in between locations of the loft blocks  32 . The tube support slider  65  can be similar to the loft block slider  33  in design and operation. The tube support slider  65  can comprise a front slider arm  58  spaced apart from a rear slider arm  60 , and a support bar  61  on each end of the tube support slider  65  connecting the front and rear slider arms  58 ,  60 , respectively. Each of the front and rear tube support slider arms  58 ,  60  can include a groove  62  along the length of the slider arm  58 ,  60 . The groove  62  can be adapted to slidingly engage a respective upper front rail or upper rear rail  56  along the length  16  of the tube  11 . By sliding the tube support slider groove  62  along the upper tube rails  56 , the tube support slider  65  can be positioned at a desired location along the length  16  of the tube  11 . 
     The tube support slider  65  can further include a locking mechanism  64  disposed on each of the front and rear slider arms  58 ,  60 , respectively, for locking the tube support slider  65  in a desired position along the length  16  of the tube  11 . The tube support slider locking mechanism  64  can include the tab  63  located on each end of the front and rear slider arms  58 ,  60 , respectively, and a biasing mechanism attached to each tab  63 . When the tabs  63  are depressed, the biasing mechanism is released and the tube support slider  65  can be slid along the front and rear tube rails  56 . When the tabs  63  are released, the biasing mechanism is actuated so as to lock the tube support slider  65  onto the front and rear tube rails  56 . 
     In certain embodiments, the loft block sliders  33  and the tube support sliders  65  can provide structural support to the compression tube  11  so as to help prevent the tube  11  from bowing outwardly in a perpendicular direction relative to the length  16  of the tube  11 . As horizontal stress is placed on the lift system  10  between the drive mechanism  23  and the loft blocks  32  by a load attached to the cables, the tube  11  may have a tendency to bow outwardly from front  12  to back  13 . Thus, the loft block sliders  33  and the tube support sliders  65  can help prevent the tube  11  from bowing outwardly in a perpendicular direction relative to the length  16  of the tube  11 . 
     Some embodiments of the lift assembly system  10 , for example, as shown in  FIG. 11 , can include a plurality of the tubes  11  arranged end-to-end. A plurality of the loft blocks  32  can be positioned along each of the modular tubes  11 , and one of a plurality of the elongate members  31  can be routed about each of the loft blocks  32 . 
       FIG. 11  shows the plurality of elongate members  31 , or cables, coming from the drive mechanism  23  unattached in the bottom  15  of the tube  11 . In some embodiments, the plurality of cables  11  can be attached to the cable belt  47 ,  48 , for example, as shown in  FIG. 6 . The cable belt  47 ,  48  can have a width substantially equal to a width of the drum  25 , and can be windably attached to the drum  25 . As illustrated in  FIG. 11 , the head block  39  can include a series of channels  59  for aligning and directing each of a plurality of the cables  31 . The drum  25  and the first and second traction drives  26 ,  27 , respectively, can also each include a plurality of channels  59  in their respective surfaces, each channel  59  being configured to align and direct one of a plurality of the cables  31  along its path. Certain embodiments of the head block  39 , as shown in  FIG. 11 , can include a bifurcated rotating surface such that the cables  31  can be spaced apart into two groups so as to provide a space in the center along the length  16  of the tube  11  for locating the loft blocks  39 . 
     As shown in  FIGS. 11 and 12 , an embodiment of the lift system  10  can further include a tube overhead connector  66  adapted to secure the tube  11  to the overhead structure  87 . The tube overhead connector  66  can include a front connector sleeve  68  and a rear connector sleeve  69 . Each connector sleeve  68 ,  69 , can be slidably disposed on the top  14  and along the length  16  of the tube  11 . The tube overhead connector  66  can have two cooperating portions  67  slidable along the tube  11  away from and toward each other, and a securing mechanism to secure the cooperating portions  67  to each other and about the overhead structure  87 . The securing mechanism can be, for example, a biasing mechanism configured to push the cooperating portions  67  together, or a nut and bolt adapted to pull the cooperating portions  67  together. The cooperating portions  67  of each of the front and rear connector sleeves  68 ,  69 , respectively, can be connected to each other with a connector rod  75 . The tube overhead connector  66  can further include a triangular-shaped cut-out  72  adapted to fit about a variety of thicknesses of the overhead structure  87 . For example, different I-beams used as roofing structural supports  87  can have varying shapes and thickness of the flanges of the I-beam. The triangular cut-outs  72  can accommodate such varying shapes and thickness so that a particular tube overhead connector  66  can be utilized with different I-beams. 
     The tube overhead connector  66  can be connected to a rail (not shown) on the top  14  and along the length  16  of the tube  11 . A block of material  73  can be fastened with one or more of the fasteners  74  to the inside surfaces of the front and rear legs  70 ,  71 , respectively, of each of the front and rear connector sleeves  68 ,  69 , respectively. The blocks of material  73  can be spaced apart such that the rail, for example, a T-shaped rail, on the top  14  of the tube  11  can fit between and rest on top of the blocks of material  73 . In this manner, the tube overhead connectors  66  can be slidably secured to the tube  11 . The tube overhead connector  66  can comprise various materials sufficiently strong to support the weight of the lift system  10  and associated loads. For example, the tube overhead connector  66  can be made of steel. The blocks of material  73  can comprise, for example, a nylon material that can help absorb sound between the contacting surfaces of the tube  11  and the tube overhead connector  66 . 
     In an embodiment in which each connector sleeve  68 ,  69  is slidably disposed on the top  14  and along the length  16  of the compression tube  11 , the tube  11  can slide, or “float,” along the longitudinal axis, or length  16  of the tube  11 . That is, as horizontal stress is placed on the tube  11  by pressure on the cables  31  between the drive mechanism  23  and a load attached to the cables  31 , the compression tube  11  can 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 structures  87  to which it is attached. In such an embodiment, at least one tube overhead connector  66  can fix one point of contact on the tube  11  to an overhead support structure  87 , and one or more of the tube overhead connectors  66  can be slidably disposed on the tube  11 . In this manner, the compression tube  11  can compress horizontally and thereby absorb horizontal stress. 
     As shown in  FIG. 13 , an embodiment of the lift system  10  can further include a load-side braking mechanism  36 . Such a braking mechanism  36  can be connected to the elongate member  31  and movable within the tube  11 . The braking mechanism  36  can include a pair of brake cables  76  extending the length  16  of the tube  11  and secured to each end  20 ,  21  of the tube  11 . A pair of spaced-apart plates  77  having grooves  78  in internal faces of the plates  77  can be configured for sliding about the pair of brake cables  76 . A brake assembly  79  disposed between the plates  77  can include a pivot structure  80  and a rocker arm  81  at the connection with the elongate member  31 . The rocker arm  81  can be urged along an angled rocker arm guide  82  into contact with one of the brake cables  31 . When tension on the elongate member  31  exerted by the drive mechanism  36  decreases below a preset threshold, the pivot structure  80  can pivot  86  so that the rocker arm  81  engages the brake cable  76 , thereby stopping movement of the elongate member  31 . 
     The brake assembly  79  can include a delay mechanism adapted to momentarily delay engagement of the brake cables  76  by the rocker arms  81  after tension on the elongate member  31  decreases below the threshold. As shown in  FIG. 13 , the pivot structure  80  can include a first pivot arm  83  and a second pivot arm  84  smaller than the first pivot arm  83 . The first and second pivot arms  83 ,  84 , respectively, can be connected with a pair of pivot arm connectors  85  such that when the first pivot arm  83  pivots  86  in the elongate member&#39;s path of travel, the second pivot arm  84  is also pivoted  86 . The different sizes of the first and second pivot arms  83 ,  84 , respectively, provides a mechanical advantage between the two pivot arms  83 ,  84  such that a small decrease in tension on the elongate member  31 , for example, a momentary decrease in tension during start-up of the motor  28 , will not cause the rocker arms  81  to engage the brake cables  76 . 
     Some embodiments of the present invention can include a method for raising and lowering the article  22  in one or more directions utilizing the lift system  10  as described herein. For example, such a lift system  10  can comprise a substantially rectangular tube  11 ; a rotatable drum  25  external to the tube  11 ; a drive mechanism  23  structurally connected to one end  20  of the tube externally, and comprising a motor  28  rotatingly connected to a first traction drive  26  and operably connected to the drum  25  and to a second traction drive  27 ; a head block  39  fixedly connected to an opposite end  21  of the tube  11 ; and a loft block  32  spaced from the head block  39  and connected to the tube  11  internally. Some embodiments of such a method can include connecting the tube  11  to the overhead structure  87 . The method can further include routing the elongate member  31  attached on one end to the drum  25  through a generally horizontal path of travel from the drum  25  to the first and second traction drives,  26 ,  27 , respectively, to the head block  39 , and to the loft block  32 , and then through a generally vertical path of travel downward from the loft block  32 . The method can further include attaching the end of the elongate member  31  opposite the drum  25  to the article  22 ; winding the elongate member  31  about the drum  25  to raise the article; and unwinding the elongate member  31  from the drum  25  to lower the article  22 . 
     In some embodiments of a method, each of a plurality of the loft blocks  32  can be positioned at a different desired location selected from an infinite number of locations along a length  16  of the tube  11 . The tube  11  can further comprise a substantially rigid, compressible material, and such a method can include compressing the tube  11  with at least a portion of a horizontal load placed on the lift system  10  between the drive mechanism  23  and the loft block  32 . In certain embodiments, tension on the elongate member  31  can be controlled during winding and unwinding. For example, the drive mechanism  23  can include a tension clutch  37  connected to the drum  25 . Varying amounts of tension can be applied with the tension clutch  37  on the drum  25  to allow the drum  25  to rotate at varying speeds relative to the rotational speed of the first traction drive  26 , thereby controlling tension on the elongate member  31  during winding and unwinding. 
     In some embodiments of a method, movement of the article  22  can be altered, for example, slowed and/or stopped, with a load-side braking mechanism  36  connected to the elongate member  31  and movable within the tube  11 . In certain embodiments, the lift system  10  may include a plurality of each of the tubes  11 , the loft blocks  32 , and the elongate members  31 . The tubes  11  can be arranged in an end-to-end configuration, and one of the elongate members  31 , or cables, can be routed about each of the loft blocks  32 . 
     In some embodiments of a method, a sensor can be located relative to the article  22  attached to the elongate member(s)  31  to detect an obstruction in the path of travel of the article  22 . A signal can be transmitted from the sensor to a controller in response to detecting the obstruction. Movement of the article  22  can then be altered in response to the transmitted signal. In certain embodiments, movement of the elongate member  31  and the attached article  22  can be controlled with a programmable controller, such as a computer  49 . In particular embodiments, the lift system  10  can 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 system  10  of the present invention can be configured for operably connecting to an existing counterweight system. In such an embodiment, the lift system  10  can cooperate with existing counterweights. For example, the drive mechanism  23  can actuate the counterweights in coordination with movement of the cables  31 . 
     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 system  10  can 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 system  10  may 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.