Abstract:
A track roller assembly for supporting telescoping boom sections of aerial devices. The track roller assembly is positioned in an interior channel of a hollow first boom section. The track roller assembly supports a majority of the weight of a second boom section and facilitates the second boom section telescoping in and out of the first boom section. The track roller assembly comprises a bracket to securely couple the track roller assembly to the interior channel of the first boom section, a plurality of rollers rotatably connected to the bracket, and a continuous track engaging the plurality of rollers on an interior surface and adjacent to the second boom section on an exterior surface.

Description:
BACKGROUND 
       [0001]    1. Field 
         [0002]    Embodiments of the invention relate to boom assemblies. More specifically, embodiments of the invention relate to a track roller assembly for supporting a boom section and facilitating the telescoping of the boom section. In further embodiments of the invention, the boom section is formed of fiberglass. 
         [0003]    2. Related Art 
         [0004]    Utility workers utilize an aerial device to reach inaccessible locations. The aerial device is usually mounted on a utility truck and generally includes a boom assembly with a utility platform connected at a boom tip. The utility platform includes a bucket, sometimes referred to as a platform, in which one or more utility workers stand. Alternatively, or in addition, the boom assembly may have a winch or other tool at the boom tip. 
         [0005]    Electric utility workers typically use an aerial device to access overhead electric power lines and electric power components for installation, repair, or maintenance. Utility workers in these situations will often utilize an aerial device that is electrically insulated and/or electrically isolated to prevent the discharge of electricity through the utility truck, and especially through the utility worker. Many aerial devices utilize at least one boom section that is formed of fiberglass or other electrically non-conductive material. The use of such material in the boom section insulates and isolates a utility worker or other tool or implement. While fiberglass has excellent insulating properties, it is susceptible to contact stresses and abrasion. Some fiberglass boom sections therefore utilize a roller mounted within the outer boom section to minimize damage to the fiberglass boom section. However, if the roller is too hard it can cause just as much damage, and if the roller is too soft its useful life is limited. 
       SUMMARY 
       [0006]    Embodiments of the invention solve the above-mentioned problems by providing a track roller assembly for supporting and facilitating the telescoping of the fiberglass boom section. The track roller assembly comprises a plurality of rollers and a continuous track disposed around the rollers. The track roller assembly is located at least partially within a hollow first boom section. The rollers are rotatably coupled to either a bracket or the interior of the first boom section. The fiberglass boom section contacts the continuous track, such that the continuous track provides a larger surface area than a single roller. 
         [0007]    A telescoping boom assembly for an aerial device in accordance with a first embodiment comprises a first boom section, a second boom section, and a track roller assembly. The second boom section is at least partially disposed within the first boom section. The track roller assembly is coupled to an interior channel of the first boom section, such that the second boom section is in contact with the track roller assembly. The track roller assembly provides support and facilitates the telescoping of the second boom section in and out of the first boom section. 
         [0008]    A track roller assembly in accordance with a second embodiment comprises a bracket, a plurality of rollers, and a continuous track disposed around the plurality of rollers. The bracket is deformable into a first interfacing shape and a second interfacing shape. The plurality of rollers comprises a first roller, a second roller, and at least one secondary roller. The first roller is rotatably coupled at one end of the bracket, and a second roller is rotatably coupled at a second end of the bracket. The at least one secondary roller is disposed between the first roller and the second roller and rotatably coupled to the bracket. Upon the placement of a heavy load onto the boom assembly, the bracket will deform such that the at least one secondary roller contacts the interior surface of the continuous track. This will provide additional support and further distribute the load. 
         [0009]    This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Other aspects and advantages of the current invention will be apparent from the following detailed description of the embodiments and the accompanying drawing figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         [0010]    Embodiments of the current invention are described in detail below with reference to the attached drawing figures, wherein: 
           [0011]      FIG. 1  is an environmental view of a utility truck with an attached boom assembly; 
           [0012]      FIG. 2  is a fragmentary cross-sectional view along a length of the boom assembly; 
           [0013]      FIG. 3  is a perspective view of the boom assembly in  FIG. 1 ; 
           [0014]      FIG. 4  is a perspective view of the boom assembly as illustrated in  FIG. 3 , but with an outer boom removed to more clearly show a first embodiment of a track roller assembly; 
           [0015]      FIG. 5  is a cross-sectional view through a width of the boom assembly illustrating the position of two track roller assemblies in the boom assembly; 
           [0016]      FIG. 6  is a perspective view of the first embodiment of the track roller assembly; 
           [0017]      FIG. 7  is a perspective view of the first embodiment of the track roller assembly, illustrating a removed continuous track to expose the plurality of rollers; 
           [0018]      FIG. 8  is an exploded view of the first embodiment of the track roller assembly and its component parts; 
           [0019]      FIG. 9  is a side view of a second embodiment of the track roller assembly that comprises five rollers and illustrated in a first interfacing position; and 
           [0020]      FIG. 10  is a side view of the second embodiment of the track roller assembly of  FIG. 9  illustrated in a second interfacing position. 
       
    
    
       [0021]    The drawing figures do not limit the current invention to the specific embodiments disclosed and described herein. The drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the invention. 
       DETAILED DESCRIPTION 
       [0022]    The following detailed description references the accompanying drawings that illustrate specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments can be utilized and changes can be made without departing from the scope of the current invention. The following detailed description is, therefore, not to be taken in a limiting sense. The scope of embodiments of the invention is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled. 
         [0023]    In this description, references to “one embodiment,” “an embodiment,” or “embodiments” mean that the feature or features being referred to are included in at least one embodiment of the technology. Separate references to “one embodiment,” “an embodiment,” or “embodiments” in this description do not necessarily refer to the same embodiment and are also not mutually exclusive unless so stated and/or except as will be readily apparent to those skilled in the art from the description. For example, a feature, structure, act, etc. described in one embodiment may also be included in other embodiments, but is not necessarily included. Thus, the current technology can include a variety of combinations and/or integrations of the embodiments described herein. 
         [0024]    An aerial device  10 , constructed in accordance with various embodiments of the invention, is shown in  FIG. 1 . The aerial device  10  utilizes a tool  12  to perform tasks that could include, but are not limited to: raising and lowering one or more people located inside of a utility platform; lifting a pallet of wood with a crane; drilling a hole for the emplacement of a pole or post; or excavating material such as dirt or sand by way of an earth-interfacing implement (not illustrated). The aerial device  10  generally includes a telescoping boom assembly  14  mounted on a base  16 . The base  16  may be a large earth-working vehicle with wheels or tracks, a utility truck, or the like, as further discussed below. In the embodiment illustrated in  FIG. 1 , the base  16  is a truck on which the aerial device  10  is mounted. In another embodiment, the tool  12  supported by the aerial device  10  comprises a video camera, a microphone, or a photography camera. In this embodiment, the aerial device  10  comprises a base  16  that is selectively movable or stationary. The boom telescopes to achieve angles for the camera or microphone that a cameraperson could not achieve individually. 
         [0025]    The telescoping boom assembly  14  broadly comprises a first boom section  18 , a second boom section  20 , and a track roller assembly  22 . The track roller assembly  22  spreads the load placed upon the second boom section  20  across a greater surface area to prevent damage to the second boom section  20 . In embodiments of the invention, the boom assembly  14  may comprise additional equipment including any of the following: power lines for the routing of hydraulic, pneumatic, or electrical power; communication wires for user-controls located on the boom assembly  14 ; or support cables (not illustrated). 
         [0026]    The base  16  of the aerial device  10  is a selectively stabilized platform. In embodiments of the invention, the base  16  is a utility truck, a crane, an oil rig, or other fixed structure. The base  16  provides stability and a counterweight to the load and the various boom sections. Larger loads typically require a more stable and a heavier base  16 . To achieve this stability, in embodiments of the invention, the base  16  may utilize hydraulic stabilizers, outriggers, and/or sand bags. 
         [0027]    As used herein, the “first boom section” refers to an exterior boom section of the boom assembly  14  that has a larger diameter or vertical cross-sectional area about the width than the second boom section  20 . As used herein, the “second boom section  20 ” refers to an inner boom section that has a smaller diameter or vertical cross-sectional area about the width than the first boom section  18 . The second boom section  20  is at least partially disposed within the first boom section  18 . The second boom section  20  telescopes to extend or retract into the first boom section  18 . In embodiments of the invention, a second boom section  20  can serve as the first boom section  18  for a third boom section that is yet a further inner section that has a smaller diameter or vertical cross-sectional area about the width than the second boom section  20 . The third boom section is at least partially disposed within the second boom section  20 , which is itself at least partially disposed within the first boom section  18 . In still further embodiments, the boom assembly further comprises a fourth boom section, a fifth boom section, etc. 
         [0028]    As shown in  FIGS. 1 and 2 , in one embodiment of the invention the first boom section  18  is rectangular about its vertical cross-section, i.e., the cross-section through a width of the boom section  18 , and the second boom section  20  is round about its vertical cross-section. In other embodiments, other shapes can be used, such as ovals, squares, pentagons, hexagons, octagons, or other regular and irregular shapes. In some embodiments, the first boom section  18  and the second boom section  20  will have a substantially similar cross-sectional shape. In other embodiments, the cross-sectional shapes are different. 
         [0029]    As shown in  FIGS. 1 and 2 , the first boom section  18  comprises an elongated body that is at least partially hollow. The first boom section  18  presents a distal end  24  having a leading edge  26 , a proximal end  28  having a trailing edge  30 , a length, and an interior channel  32  extending through the hollowed body. In embodiments of the invention, the first boom section  18  is formed of fiberglass or a polymer. In other embodiments, the first boom section  18  is formed of metal. The proximal end  28  of the first boom section  18  is rotationally coupled to the base  16 . In some embodiments, the proximal end  28  of the first boom section  18  is rotationally coupled to the base  16  such that the boom assembly  14  can rotate along more than one axis. In embodiments of the invention, the first boom section  18  presents a mount for the second boom section, which is schematically illustrated in  FIG. 1 . In embodiments of the invention, the first boom section  18  may further comprise a covering (not illustrated) over its trailing edge  30 . The covering may be partially open to receive any of the power lines, communication wires, or cable. 
         [0030]    The interior channel  32  of the first boom section  18  is of a sufficient vertical cross-sectional area about the width such that the interior channel  32  may house the second boom section  20  and the track roller assembly  22 , as will be discussed below. In embodiments of the invention, the interior channel  32  may further house power cables, including hydraulic cables, communications lines, etc. In other embodiments, these cables and lines are coupled to the exterior of the first boom section  18 . 
         [0031]    Referring to  FIG. 3 , the first boom section  18  may further include any or all of the following at the distal end  24  of the section  18 : one or more exterior mounts  34  for an attached tool  12 , a support flange  36 , and a mount  38  for the track roller assembly  22 . In embodiments of the invention, the first boom section  18  has a different vertical cross-sectional size and/or shape for a portion of its length near the distal end  24 . In other embodiments, the first boom section  18  has a substantially constant vertical cross-sectional size and shape all along the length. As best shown in  FIG. 3 , in embodiments of the invention, the support flange  36  may be splayed around multiple sides of the distal end  24  of the first boom section  18 . The support flange  36  provides additional bracing material around the distal end  24 . The mount  38  for the track roller assembly  22  is located in the interior channel  32  of the first boom section  18 . The mount  38  is generally flat to accept the track roller assembly  22 . In embodiments, there is a plurality of mounts  38  to accept a plurality of track roller assemblies  22 . 
         [0032]    As shown in  FIGS. 2-3 , the second boom section  20  of the boom assembly  14  comprises an elongated body. The second boom section  20  presents a distal end  40  having a leading edge  42 , a proximal end  44  having a trailing edge  46 , and a length. In embodiments the second boom section  20  is solid (i.e., the second boom section  20  is not hollow). In other embodiments, the second boom section  20  is hollow. In some embodiments, the hollow second boom section  20  is adapted to receive a third boom section (not illustrated). 
         [0033]    The second boom section  20  may telescope into a plurality of positions with respect to the first boom section  18 , including a fully retracted position, in which the length of the body of the second boom section  20  is substantially inserted within the first boom section  18  (see,  FIG. 3 ), and a fully extended position, in which only a relatively small portion of the length of the body of the second boom section  20  is inserted within the first boom section  18 . In embodiments of the invention, a plurality of intermediate positions is also possible. In embodiments of the invention, the length of the second boom section  20  is substantially the same length of the first boom section  18 . In other embodiments, the second boom section  20  may be shorter or longer than the first boom section  18 . 
         [0034]    The second boom section  20  is formed of fiberglass, a composite, or other polymer. Fiberglass has electrically insulative properties that electrically isolate the operator or tool and prevent a discharge of electricity from the power line through the fiberglass. In still other embodiments, the second boom section  20  is formed of a polymer. In yet further embodiments, the second boom section  20  is formed of metal. 
         [0035]    In embodiments of the invention, the distal end  40  of the second boom section  20  is coupled to the tool  12 , utility platform, or other device for performing work. As noted above, multiple types of tools  12  could be used with the boom assembly  14 . For example, the tool may be a pulley for guiding a cable and a hook, an earth-working implement, such as a digger derrick, or a platform upon which a utility worker can stand. 
         [0036]    Referring now to  FIG. 2 , in embodiments of the invention the second boom section  20  further comprises a base segment  48  coupled to the trailing edge  46  of the proximal end  44 . The base segment  48  presents a top edge  50 . When a load  52  is placed on the distal end  40  of the second boom section  20 , the downward force of the load  52  translates to an upward force on the proximal end  44  of the second boom section  20 . Therefore, at least when the load  52  is relatively heavy and placed on the distal end  40  of the second boom section  20 , the top edge  50  of the base segment  48  is in contact with the interior channel  32  of the first boom section  18 . It should be appreciated that the same would be true if the heavy load  52  was placed on a third boom section or a fourth boom section, etc., as these forces could damage the second boom section  20 . 
         [0037]    As illustrated in  FIG. 2 , the second boom section  20  further comprises a wear pad  54 . In one embodiment, the wear pad  54  is coupled to the top edge  50  of the base segment  48 . In another embodiment, the wear pad  54  is coupled to the interior channel  32  of the first boom section  18 . In still further embodiments, multiple wear pads  54  are utilized. The wear pad  54  has a relatively low coefficient of friction so as to facilitate the translation of the second boom section  20  within the first boom section  18 . In some embodiments, the wear pad  54  is removably coupled to the second boom section  20 , such that it can be easily replaced upon being damaged or worn. 
         [0038]    The second boom section  20  telescopes to extend out of the first boom section  18  and retract into the first boom section  18 . A hydraulic cylinder (not illustrated) applies hydraulic power to the second boom section  20 . The hydraulic cylinder is coupled to the base segment  48  of the second boom section  20  and to the first boom section  18 . In one embodiment of the invention, the hydraulic cylinder acts as a double acting cylinder. In other embodiments, the boom assembly  14  acts as a single acting cylinder. In still further embodiments, the second boom section  20  telescopes via electrical power. 
         [0039]    Turning now to  FIGS. 5-8 , the track roller assembly  22  of the telescoping boom assembly  14  will be described. The track roller assembly  22  facilitates the telescoping of the second boom section  20  in and out of the first boom section  18 . The track roller assembly  22  is adapted to rotate a continuous track  56  with minimal friction. The track roller assembly  22  comprises a mounting assembly  58 , a plurality of rollers  60 , and the continuous track  56 . The mounting assembly  58  rotatably couples each of the plurality of rollers  60  to the interior channel  32  of the first boom section  18 . Each of the plurality of rollers  60  is adapted to rotate about a respective center axis. The continuous track  56  is wrapped around each of the plurality of rollers  60 , such that at least two of the plurality of rollers  60  are in contact with the continuous track  56 . 
         [0040]    As illustrated in  FIG. 5 , the telescoping boom assembly  14  comprises a plurality of track roller assemblies  22 . The track roller assembly  22  is securely coupled to the mount  38  on the first boom section  18 . In embodiments as discussed below, the track roller assembly  22  is deformable into at least a first interfacing shape, as shown in  FIG. 9 , and a second interfacing shape, as shown in  FIG. 10 . 
         [0041]    The mounting assembly  58  is illustrated in  FIGS. 5-8  and comprises a generally U-shaped bracket  62 , a roller housing  64  having at least one opening  65  in which the plurality of rollers  60  is attached, and securing pins  66  for securing the plurality of rollers  60  in the roller housing  64 . The mounting assembly  58  is formed of metal or other rigid structure that can withstand the weight of the first and second boom sections  18 , 20 , the load  52 , and the stresses accompanying the telescoping of the boom sections  18 , 20 . 
         [0042]    As best illustrated in  FIG. 8 , the bracket  62  includes a mounting plate  68  and opposing arms  70  extending upwardly from the mounting plate  68 , such that the mounting plate  68  and opposing arms  70  form the general U-shaped bracket  62 . The mounting plate  68  is generally flat and includes a plurality of openings  72  to receive fasteners  74 , such as screws or bolts. In embodiments of the invention, the mounting plate  68  is secured to the interior channel  32  of the first boom section  18 , as illustrated in  FIGS. 3 and 5 . The mounting plate  68  is sized and shaped to fit flush against the mount  38  of the first boom section  18 . In embodiments of the invention, the plate  68  may be another shape to complement a shape of the mount  38  of the first boom section  18 . For example, if the mount  38  of the first boom section  18  is curved, the mounting plate  68  may also be curved so that substantially all of a bottom surface of the plate  68  may be in contact with the mount  38  of the first boom section  18 . 
         [0043]    The mounting plate  68 , and thus the bracket  62 , is secured to the mount  38  of the first boom section  18  by inserting screws or fasteners  74  through the plurality of openings  72  in the mounting plate  68  and into the first boom section  18 . Other securement methods may also be employed, such as adhering the mounting plate  68  to the first boom section  18  via a high-strength adhesive, welding the mounting plate  68  to the first boom section  18 , or integrally forming the mounting plate  68  (and/or the bracket  62 ) with the first boom section  18 . 
         [0044]    As noted above, the arms  70  extend upwardly from the plate  68  and are spaced from each other to form a receiving area  76  for the roller housing  64 . The arms  70  are integrally formed with the mounting plate  68 , such that the bracket  62  comprising the mounting plate  68  and arms  70  is a monolithic unit. Each arm  70  includes an opening  78  therethrough for receiving the securing pins  66 , as further described below. 
         [0045]    The roller housing  64  is sized and configured to rest within the receiving area  76  formed by the mounting plate  68  and upwardly extending arms  70 . The roller housing  64  is generally H-shaped (when viewed from above) and comprises two spaced side plates  80  and a support bar  82  extending therebetween. Each side plate  80  has a generally oblong shape that allows the continuous track  56  to roll around an exterior edge of the side plate  80  during use of the track roller assembly  22 . 
         [0046]    One advantage of the roller housing  64  is being able to quickly and easily replace the track roller assembly  22  should one or more of the rollers  60  or the track become damaged. Another advantage is the ability of the roller housing  64  to pivot about the securing pin  66 . The pivoting action allows each of the rollers  60  to stay in contact with the second boom section  20  even if the second boom section  20  is not substantially parallel to the first boom section  18  due to a heavy load  52  being placed on the second boom section  20  or the third boom section. 
         [0047]    The roller housing  64  is pivotably coupled to the arms  70  via the securing pin  66 , such that the roller assembly  68  can be pivoted up and down in the longitudinal direction of the first boom section  18 . The securing pin  66  is emplaced through the opposing arms  70  and the support bar  82  when the roller housing  64  is in the receiving area  76  of the bracket  62 . Pivoting allows the track roller assembly  22  to accommodate the second boom section  20  based upon the extended position of the second boom section  20  relative to the first boom section  18  and the weight of the load  52  placed upon the second boom section  20 . The securing pin  66  may also utilize at least one securing washer  84  to facilitate the pivoting. The securing washer  84  facilitates the pivoting of the roller housing  64  around the securing pin  66  and prevents damage to each. The securing pin  66  and the at least one securing washer  84  are formed of a metal. In other embodiments, the securing pin  66  and the at least one securing washer  84  are formed of a hardened polymer. In another embodiment, the roller housing  64  is fixedly secured to the arms  70 . In yet another embodiment, the roller housing  64  and the arms  70  are monolithic. 
         [0048]    The track roller assembly  22  comprises a plurality of rollers  60 , including at least a first roller  86  and a second roller  88 . Each of the plurality of rollers  60  is wheel or cylindrically shaped and presents an outer rim  90 . The outer rim  90  of the rollers  60  presents a vertical cross-sectional shape across the outer rim  90 . As shown in  FIG. 8 , the cross-sectional shape can be substantially flat. In other embodiments, the cross-sectional shape may be convex, concave, arcuate, semi-circular, V-shaped, or A-shaped. The rollers  60  are adapted to freely rotate about an axis that is substantially perpendicular to the longitudinal direction of the first boom section  18 . As such, the outer rim  90  of the rollers  60  rotates in a direction substantially parallel to the longitudinal direction of the first boom section  18 . The rollers  60  are substantially rigid so as to support the load  52  of the second boom section  20  as it telescopes into the plurality of positions with respect to the first boom section  18 . Each roller  60  has a diameter such that a portion of the outer rim  90  of the roller  60  extends beyond the roller housing  64  when the roller  60  is rotatably coupled to the roller housing  64 . This allows for the free rotation of the continuous track  56  about the rollers  60 . 
         [0049]    The arms  70  are adapted to rotatably couple the plurality of rollers  60 . In embodiments, a plurality of securing pins  66  is utilized to rotatably couple each of the plurality of rollers  60  to the arms  70 . Each of the plurality of securing pins  66  is disposed in the opening  78  in the arms  70  and through a respective opening  92  in each of the rollers  60 . The securing pin  66  is substantially cylindrical such that the roller  60  may rotate about the securing pin&#39;s  66  vertical cross-section about the width. The securing pin  66  may further comprise a head  94 . The head  94  of the securing pin  66  is adapted to secure the securing pin  66  to the roller housing  64 , the arms  70  of the bracket  62 , or the interior channel of the first boom section  18 . One roller  60  is placed into the receiving area  76  between the two arms  70  of the roller housing  64 , and one securing pin  66  passes through the opening  92  in the roller  60  and the pair of arms  70  in the roller housing  64 . In embodiments of the invention, the securing pin  66  further comprises a plurality of bearings to facilitate free rotation of the roller. 
         [0050]    In other embodiments, the track roller assembly  22  further comprises at least one securing washer  84 , which presents an interior diameter approximately equal to, or slightly larger than, an outer diameter of the securing pin  66 . This allows the securing washer  84  to be disposed around the securing pin  66  when it is attached to the roller assembly  68 . 
         [0051]    The continuous track  56  of the roller assembly  68  of the track roller assembly  22  is a belt presenting an interior surface  96  and an exterior surface  98 . In embodiments of the invention, the continuous track  56  is formed of one or more layers of pliable material, such as a polymer or composite. The pliable material provides linear strength and retains the shape of the continuous track  56 . The pliable material has a high compliance, which is the inverse of stiffness, such that it will easily deform under the forces. The compliance is advantageous in facilitating the rotation of the continuous track  56  and in providing greater contact surface area with the second boom section  20 . The pliable material of the continuous track  56  also has a lower elastic modulus than the second boom section  20 . The pliable material will therefore deform to a greater extent than the material of the second boom section  20 . Because the second boom section  20  rests on the exterior surface  98  of the continuous track  56 , the continuous track  56  prevents and/or reduces damage to the second boom section  20  caused by the force of the load  52 . 
         [0052]    In other embodiments, the continuous track  56  comprises a plurality of pivotably linked segments (not illustrated). Each of the plurality of segments is rigid or semi-rigid. 
         [0053]    The interior surface  96  of the continuous track  56  is disposed around the first roller  86  and second roller  88 . In embodiments of the invention, the interior surface  96  of the continuous track  56  is substantially smooth. In other embodiments, the interior surface  96  of the continuous track  56  further comprises a plurality of protrusions (not illustrated) that are disposed in a corresponding plurality of recesses (not illustrated) in the first roller  86  and the second roller  88 . In embodiments, the first roller  86  and the second roller  88  may have a plurality of teeth or cogs (not illustrated), so as to present a sprocket shape. 
         [0054]    The exterior surface  98  of the continuous track  56  is substantially smooth. In other embodiments, the exterior surface  98  of the continuous track  56  further comprises a plurality of protrusions (not illustrated) or recesses (not illustrated), also called tread. The recesses and protrusions may provide advantages including facilitating the rotation of the continuous track  56  around the roller  60 ; ensuring that a rotation of the continuous track  56  corresponds to a similar rotation of the first roller  86  and the second roller  88 , so as to minimize damage to the continuous track  56 ; ensuring that the continuous track  56  rotates in a direction substantially parallel to the rotation direction of the first roller  86  and the second roller  88 , so as to minimize the likelihood that the continuous track  56  will slip or dislodge off the rollers  60 ; and providing increased frictional contact between the continuous track  56 , so as to provide a stable support for the second boom section  20 . 
         [0055]    A track roller assembly  22  in accordance with another embodiment of the invention further comprises at least one roller  60  that is a secondary roller  100 . The at least one secondary roller  100  is rotatably coupled to the roller housing  64  between the first roller  86  and the second roller  88 . The at least one secondary roller  100  provides the advantage of distributing the weight of the second boom section  20  and the load  52  more evenly. 
         [0056]    In embodiments, the roller housing  64  is deformable or deflectable into a first interfacing shape, as illustrated in  FIG. 9 , and a second interfacing shape, as illustrated in  FIG. 10 . In the first interfacing shape, only the first roller  86  and the second roller  88  are in contact with the interior surface  96  of the continuous track  56  that is adjacent to the second boom section  20 . In the second interfacing shape, the first roller  86 , second roller  88 , and each of the at least one secondary roller  100  is in contact with the interior surface  96  of the continuous track  56  that is adjacent to the second boom section  20 . 
         [0057]    In one embodiment of the invention, the roller housing  64  is formed of a material, such as a polymer or a metal, that deforms or deflects upon the application of a heavy load  52 . In another embodiment of the invention, the roller housing  64  further comprises a compression element (not illustrated), such as a spring, which provides a force pushing the roller housing  64  into the first interfacing position. Upon the application of a heavy load  52 , the compression element compresses until the at least one secondary roller  82  interfaces with the interior surface  96  of the continuous track  56 . In one embodiment, as illustrated in  FIGS. 9-10 , the roller housing  64  has a substantially V-shape when in the first interfacing position and has a substantially straight shape when in the second interfacing position. In another embodiment of the invention, the roller housing  64  has an arcuate shape in the first interfacing position and a substantially straight shape in the second interfacing position. 
         [0058]    The installation and emplacement of the track roller assembly  22  will now be described in greater detail. The following is an exemplar of the installation and emplacement of the track roller assembly  22 . In embodiments of the invention, the roller assembly  68  is formed by the following steps: emplacing the first roller  86  into the roller housing  64  and aligning the at least one opening  65  in the roller housing  64  with the opening  92  in the first roller  86 ; emplacing the securing pin  66  through the securing washer  84 , the at least one opening  78  in the arm  70 , the opening  92  in the first roller  86 , and through another securing washer  84 ; locking the securing pin  66  to the first roller  86  to prevent its unintentional displacement; repeating steps 1-3 for the second roller  88 ; and emplacing the continuous track  56  around the first roller  86  and the second roller  88 . 
         [0059]    The track roller assembly  22  is then formed by emplacing the roller assembly  68  into the receiving area  76  between the arms  70  of the bracket  62  and aligning the at least one opening  78  in the arm  70  with a corresponding opening  65  through the support bar  82  in the roller housing  64 ; emplacing the securing pin  66  through the securing washer  84 , the at least one opening  78  in the arm  70  of the bracket  62 , the opening  65  in the roller housing  64 , and through another securing washer  84 ; and locking the securing pin  66  to prevent its unintentional displacement. The track roller assembly  22  is then installed by emplacing the track roller assembly  22  into the first boom section  18  and aligning the plurality of openings  72  in the mounting plate  68  with a corresponding plurality of openings (not illustrated) in the mount  38  of the first boom section  18 ; securing the track roller assembly  22  to the first boom section  18  by applying the plurality of fasteners  74  to the aligned openings  72  in the mounting plate  68  and the openings in the mount  38  of the first boom section  18 ; and emplacing and telescopically securing the second boom section  20  into the first boom section  18 , such that the exterior surface  98  of the continuous track  56  is adjacent an exterior portion of the second boom section  20 . 
         [0060]    In embodiments of the invention, multiple track roller assemblies  22  are installed into the first boom section  18 . In one embodiment, as illustrated in  FIG. 5 , two track roller assemblies  22  are emplaced adjacent to each other such that they provide lateral support in addition to their longitudinal support. In this embodiment, the first boom section  18  comprises two mounts  38  that form an obtuse angle near the distal end  24  of the first boom section. This embodiment of the invention is advantageous because it provides lateral support as well as vertical support to the second boom section  20 . 
         [0061]    In another embodiment, two adjacent track roller assemblies  22  are emplaced such that in the event of a failure of one, the other track roller assembly  22  provides the support for the second boom section  20  and the load  52 . In another embodiment of the invention, a plurality of track roller assemblies  22  is spaced along the longitudinal direction to further distribute the weight of the second boom section  20 . 
         [0062]    Operation and use of the track roller assembly  22  will now be described in greater detail. The track roller assembly  22  is a passive element in the telescoping boom assembly  14 . The track roller assembly  22  receives no direct power input of its own. The continuous track  56  and the rollers  60  rotate as a by-product of the friction between the second boom section  20  and the exterior surface  98  of the continuous track  56  as the second boom section  20  extends and retracts relative to the first boom section  18 . In other embodiments of the invention, the track roller assembly  22  is powered, such that the rotation of the rollers  60  provides at least some of the force that extends or retracts the second boom section  20  relative to the first boom section  18 . 
         [0063]    Although the invention has been described with reference to the embodiments illustrated in the attached drawing figures, it is noted that equivalents may be employed and substitutions made herein without departing from the scope of the invention as recited in the claims.