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You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to bridge maintenance. More specifically, it relates to an apparatus that allows a user to remotely paint, clean, and inspect bridge cables. 
     2. Description of the Prior Art 
     The United States has roughly 578,000 highway bridges. The average life span of highway bridges is about 70 years and the majority of bridges currently in use were built after 1945. In addition to old age, bridges are particularly susceptible to environmental damage, such as corrosion, cracking, and fatigue, which can affect a bridge&#39;s load carrying capacity. Therefore, routine and regularly scheduled maintenance is critical to maintaining the structural integrity of bridges. The potential penalties for ineffective inspection of bridges can be very severe, including the loss of life, the cost to build a new bridge, the loss of business resulting from limited access or detours, the cost resulting from blockage of a major shipping channel, and the environmental damage due to hazardous materials being transported over the bridge at the time of collapse. 
     Visual inspection and manual repair costs represent a very significant portion of a bridge&#39;s maintenance budget. In addition to being expensive, visual inspections and manual repairs are very dangerous. For example, maintenance workers periodically climb and suspend from cable-stayed bridges in order to inspect and repair their cables. Unfortunately, in performing these inspections and repairs, many workers have fallen to their death. 
     What is needed is an apparatus that allows a user to remotely inspect, paint, clean, and repair bridge cables. However, in view of the prior art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the art how the limitations of the art could be overcome. 
     SUMMARY OF INVENTION 
     The long-standing but heretofore unfulfilled need for an apparatus that allows a user to remotely inspect, paint, clean, and repair bridge cables is now met by a new, useful, and nonobvious invention. The invention attaches to a bridge&#39;s cable. Once attached, the apparatus is remotely directed along the longitudinal extent of the cable. A variety of maintenance devices are fastened to the end of the apparatus and allow the user to remotely and safely inspect, paint, clean, and repair the cable. 
     The invention generally includes three major components: a frame, a lateral drivetrain, and a radial drivetrain. The frame includes two annulus ends connected by a plurality of support bars. Both annulus ends include two half circle members that are bolted together to form an annulus; alternatively, the half circle members are connected by a pin joint at one end and bolted together at the other end, allowing the frame to hinge open. A plurality of lateral wheel mounts are connected to both annulus ends and secure a plurality of lateral wheels to the frame. Each lateral wheel is adjustable within the lateral wheel mount. The lateral drivetrain includes a motor with a sprocket or gearbox connected to a continuous track. Idlers are disposed within the continuous track and keep the track under tension. A housing encompasses the idlers and acts as a mount for the idlers axles. The radial drivetrain includes a motor with a gear arm or gearbox. The gear arm or gearbox engages a radial track that is disposed around a plurality of radial wheels. The plurality of radial wheels is rotatably secured to a plurality of radial wheel mounts. The plurality of radial wheel mounts is affixed to the frame. A plurality of attachment arms extends from the radial track. Each attachment arm has a maintenance device attached thereto. 
     In operation, the frame is opened to allow for placement around the cable. Once positioned around the cable, the frame is bolted together. The lateral drivetrain is then adjusted so that the continuous track is firmly against the cable. Likewise, the lateral wheels are adjusted so that they too are positioned firmly against the cable. When the lateral drivetrain is actuated, the device moves longitudinally along the cable. The radial drivetrain motor turns the gear arm or gearbox which rotates the radial track around the cable. The radial motor can be programmed to oscillate the radial track back and forth or a switch can be located in the radial path of the radial track to alternate direction. A variety of bridge maintenance devices may be affixed to the attachment arms, including spray guns, sandblasters, and video recorders. As the apparatus moves longitudinally along the cable, the bridge maintenance devices rotate around the cable allowing the user to remotely inspect or repair the cable. As recited in the claims, the novel cable maintenance apparatus includes a frame including a first annulus disposed in encircling relation to a cable, the first annulus positioned in a plane that is substantially transverse to a longitudinal axis of the cable, the frame including a second annulus disposed in encircling relation to the cable, and the second annulus positioned in a plane that is substantially transverse to the longitudinal axis of the cable. A plurality of circumferentially spaced apart support bars interconnect the first and second annuluses to one another, said support bars being disposed substantially parallel to the longitudinal axis of the cable. A lateral drivetrain has a straight configuration and is adjustably secured to the frame between the first annulus and the second annulus. The lateral drivetrain includes a first motor and a continuous track that frictionally engages the cable along a predetermined longitudinal extent thereof. The first motor is connected in driving relation to the continuous track. A radial drivetrain is secured to a preselected annulus, and a radial track is rotatably mounted to the preselected annulus. The radial track is positioned in a plane that is substantially transverse to a longitudinal axis of the cable. The radial drivetrain includes a second motor in mechanical communication with the radial track and a controller governing operation of the first motor in a first cable-climbing and in a second cable-descending direction. The controller also governs operation of the second motor so that the radial track oscillates in first and second directions relative to the longitudinal axis of the cable. The invention as claimed further includes a first plurality of lateral wheel mounts secured to the first annulus in circumferentially spaced apart relation to one another, a first plurality of lateral wheels rotatably mounted to the first plurality of lateral wheel mounts, a second plurality of lateral wheel mounts secured to the second annulus in circumferentially spaced apart relation to one another, and a second plurality of lateral wheels rotatably mounted to the second plurality of lateral wheel mounts. The first and second plurality of lateral wheels rotatably engage the cable to maintain the frame in concentric relation to the cable as the cable maintenance apparatus climbs or descends the cable. A plurality of attachment arms is affixed to the radial track, each attachment arm of the plurality of attachment arms being substantially parallel to the longitudinal axis of the cable. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a fuller understanding of the invention, reference should be made to the following detailed description, taken in connection with the accompanying drawings, in which: 
         FIG. 1  is an upper perspective view of the apparatus; 
         FIG. 2  is an exploded view of the apparatus; 
         FIG. 3  is a side view of the lateral drivetrain; and 
         FIG. 4  illustrates the apparatus being used on a cable-stayed bridge. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The invention is a cable maintenance apparatus that attaches to a cable and allows a user to remotely inspect, paint, clean, and repair the cable. Cameras, paint guns, sandblasters, and other bridge maintenance devices are attached to the apparatus and rotate about the cable as the apparatus moves along the longitudinal axis of the cable. Thus, a user can remotely inspect or paint every inch of the cable without having to climb or suspend from the cable. This invention is particularly helpful in bridge maintenance because of the dangers associated with heights. 
     As shown in  FIG. 1 , apparatus  10  includes rigid frame  12 . Specifically, annuluses  20  and  30  are connected by support bars  40  to form said frame. Annuluses  20  and  30  include two half circle members  34  and  36 , which are connected at their ends by bolts  32 . When bolts  32  are removed, frame  12  separates into two halves, allowing said frame to be positioned around cable  50 . After being positioned around cable  50 , bolts  32  are secured and frame  12  forms one rigid body. In an alternate embodiment, half circle members  34  and  36  are connected by a pin joint and bolt at their opposing ends, respectively, allowing frame  12  to hinge open so that it can be positioned around cable  50 . 
     Lateral wheel mounts  38  are affixed to annuluses  20  and  30 . Lateral wheel mounts  38  act as mounts for lateral wheels  42 . Slots  44  enables lateral wheels  42  to be slideably adjusted inward and outward so that they are positioned firmly against cable  50 . Lateral wheels  42  act as casters and ensure a smooth track as apparatus  10  moves along the lateral axis of cable  50 . 
     As depicted in  FIGS. 1 and 2 , radial drivetrain  90  includes radial motor  92 , gear arm  94 , radial track  96 , radial wheel mounts  100 , radial wheels  102 , attachment arms  104 , and maintenance devices  106 . Radial motor  92  is attached to frame  12  and turns gear arm  94 . Gear arm  94  is mechanically connected to radial track  96  and rotates radial track  96  around cable  50 . 
     In an alternate embodiment, a gearbox mechanically connects radial motor  92  to radial track  96 . Radial track  96  rests on and around radial wheels  102 . Because it rests on radial wheels  102 , radial track  96  freely rotates about the axis of cable  50 . Radial wheels  102  are mounted to radial wheel mounts  100 . Radial wheel mounts  100  are affixed to annulus  30 . Attachment arms  104  extend laterally from radial track  96  and are used to attach maintenance devices  106 . Attachment arms  104  may extend parallel to cable  50  or at an angle. Maintenance devices  106  can be any number of attachments; for example, a camera, a spray gun, or a sandblaster. In operation, control box  110  is either programmed to oscillate radial track  96  back and forth or a switch is located in the path of radial track  96 , such that when the switch is engaged by radial track  96  it alternates radial track  96 &#39;s direction. The switch would be attached to annulus  30  and in the rotational path of radial track  96 . 
     In  FIGS. 1 and 2 , radial track  96  is a partial circle so that cable  50  can be positioned within the diameter of radial track  96 . 
     In an alternate embodiment, radial track  96  is a full circle with a removable member to allow the cable to be positioned within its diameter. After cable  50  is positioned within the diameter of radial track  96 , the removable member is reattached creating a complete circle. 
     As shown in  FIGS. 2 and 3 , lateral drivetrain  60  includes lateral motor  62 , continuous track  64 , housing  66 , drive sprocket  68 , idlers  70 , and idler axles  72 . The opposing ends of lateral drivetrain  60  are adjustably attached to frame  12  at annuluses  20  and  30 , respectively. Annuluses  20  and  30  have slots  112  for slideably receiving lateral drivetrain  60 . Once positioned, lateral drivetrain  60  is secured against annuluses  20  and  30  by bolts or screws. Drive sprocket  68  mechanically connects continuous track  64  with lateral motor  62 ; in an alternate embodiment, a gearbox may be used to mechanically connect lateral motor  62  with continuous track  64 . Idlers  70  are positioned within continuous track  64  and maintain continuous track  64  under tension. Idler axles  72  are mounted to housing  66  and allow idlers  70  to rotate freely. In operation, continuous track  64  is positioned against cable  50 . Lateral motor  62  is then activated and turns drive sprocket  68  which turns continuous track  64 . The forward or backward movement of continuous track  64  moves the apparatus along the extent of cable  50 . 
     Control box  110  is attached to housing  66  in the embodiment of  FIG. 1 . Control box  110 , however, may be disposed anywhere on apparatus  10  where it does not interfere with the lateral and radial movement of the apparatus. Control box  110  houses all of the electronics and may include a CPU. 
     When using the apparatus, the frame is opened, positioned around the cable, and bolted shut. The lateral drivetrain is then adjusted so that the continuous track firmly abuts the cable and is bolted in place. Next, the lateral wheels are adjusted so that they too firmly abut the cable. The lateral and radial drivetrains are then activated through the control box. Depending on the movement of the continuous tack, the apparatus will move in both directions along the longitudinal axis of the cable. Similarly, depending on the rotation of the radial motor, the radial track and maintenance attachments will rotate around the axis of the cable. The lateral drivetrain and the radial drivetrain are independent of one another. Accordingly, for example, when paint guns are attached, the speed at which the radial drivetrain rotates the sprayers around the cable can be adjusted to correspond to the speed the apparatus is moving along the longitudinal axis of the cable so that a desired coat of paint is applied to the cable. 
       FIG. 4  shows the apparatus being used on a cable-stayed bridge. As depicted, the apparatus moves along the longitudinal extent of cable  50 . The apparatus is controlled remotely from the ground via wire  90  which is in communication with the control box; however, in an alternate embodiment, the apparatus may be adapted to be wirelessly controlled. 
     It will be seen that the advantages set forth above, and those made apparent from the foregoing description, are efficiently attained and since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matters contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Summary:
A bridge cable maintenance apparatus attaches to a cable and includes two drivetrains. Once attached, the apparatus is remotely directed along the longitudinal extent of the cable by the first drivetrain. The second drivetrain rotates attachments about the cables axis. The attachments include a variety of maintenance devices that are fastened to the end of the apparatus and allow the user to remotely and safely inspect, paint, clean, and repair the cable.