You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application 60/439,934 filed on Jan. 14, 2003. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates generally to the field of painting apparatus. More particularly, this invention relates to accessory devices for conventional paint sprayers in the form of an easily transportable cart on which a paint spray gun may be mounted for converting a conventional airless paint sprayer into a line striper to paint lines on parking lots, curbs, warehouse floors, and other pavement surfaces.  
       BACKGROUND OF THE INVENTION  
       [0003]     Devices exist for painting lines on pavement surfaces in parking lots and other locations where the line is sprayed onto the pavement by a paint spray gun. Conventional line stripers are not without their limitations, however, especially with respect to their reduced maneuverability in tight spaces, such as between vehicles that are parked in a parking lot. In particular, conventional line stripers are too big and too awkward to be able to spray lines between parked cars, for example. Another drawback with conventional line stripers is their inappropriateness to be used indoors to stripe warehouse floors, for example, due to the fact that a line striper is typically powered by a gasoline engine.  
         [0004]     Furthermore, not everyone can afford a line striper, especially when the need for one might only be an occasional event hardly worth the cost of owning one. And there are those occasions when the striping job is too small to justify the effort necessary to bring a conventional line striper to the job site.  
         [0005]     In view of the prior art the need exists for a lightweight cart onto which a spray gun may be quickly and easily mounted for surface line marking.  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention is a line striper cart having a J-shaped frame member formed of a longitudinal section and first and second transverse sections, with a plurality of wheels mounted on the frame member. The line striper cart of the present invention also includes a spray gun holder that provides a means positionable along the frame member for attaching a spray gun to the cart; and the cart further includes a spray gun extender or pole with a remote gun-operating handle that also provides a means for moving the cart by hand.  
       OBJECTS OF THE INVENTION  
       [0007]     It is therefore an object of this invention to provide a cart that can be used as an accessory device for converting an airless paint sprayer into a line striper for use on small striping jobs to paint lines on parking lots, curbs, warehouse floors and other pavement surfaces.  
         [0008]     It is also an object of this invention to provide a paint striping cart that can be easily maneuvered in tight spaces and moved with little effort from one line to the next.  
         [0009]     Another object yet of this invention is to provide a paint striping cart that can be converted from a 3-wheeled device to a 2-wheeled device for painting curved lines.  
         [0010]     Still another object of this invention is to provide a paint striping cart that is adaptable for removable mounting of a spray gun virtually anywhere on the cart for different striping applications.  
         [0011]     It is also an object of this invention to provide a paint striping cart that is adaptable for adjustable positioning of a spray gun at a desired location on the cart to optimize the spray pattern in a particular application.  
         [0012]     An additional object of this invention is to provide a paint striping cart that is relatively simple, sturdy and inexpensive, and which is easy to assemble and use.  
         [0013]     These and other objects and advantages of the invention will become apparent from the following description and the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1  is an exploded view in perspective of the present invention.  
         [0015]      FIG. 2  is a view in perspective showing the present invention generally oriented for use by a right-handed operator.  
         [0016]      FIG. 3  is a view in perspective showing the present invention generally oriented for use by a left-handed operator.  
         [0017]      FIG. 4  is an plan view of the present invention showing an orientation suitable for painting crosswalks.  
         [0018]      FIG. 5  is a fragmentary view in perspective of the present invention showing an arrangement suitable for painting a curb.  
         [0019]      FIG. 6  is a view in perspective of the present invention showing an arrangement suitable for painting curves and circles.  
         [0020]      FIG. 7  is an elevation view of the present invention shown in  FIG. 6 .  
         [0021]      FIG. 8  is a view in perspective of the present invention.  
         [0022]      FIG. 9  is a first side elevation view of a support post useful in the practice of the present invention.  
         [0023]      FIG. 10  is a second side elevation view of the support post of  FIG. 9 .  
         [0024]      FIG. 11  is a plan view of the support post taken in the direction of arrows  11 - 11  of  FIG. 9 .  
         [0025]      FIG. 12  is a partially exploded view in perspective of a spray gun holder useful in the practice of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0026]     The following detailed description is of the best mode or modes of the invention presently contemplated. Such description is not intended to be understood in a limiting sense, but to be an example of the invention presented solely for illustration thereof, and by reference to which in connection with the following description and the accompanying drawings one skilled in the art may be advised of the advantages and construction of the invention. In the various views of the drawings, like reference characters designate like or similar parts.  
         [0027]     Referring to the figures, the present invention is directed to a cart  18  including a rigid skeletal frame member  20  providing a track-like surface on which support post  22  may be attached. The frame member  20  comprises a longitudinal section  24 , a first transverse section  26  and a second transverse section  28  together providing a structure having a shape as the letter J.  
         [0028]     Preferably, frame member  20  is formed of one half-inch cold rolled steel rod, however, any material of sufficient strength and rigidity may be used in this invention. The stock may be formed in a conventional manner by any of various methods. The stock may also take the shape of different forms, besides round cross-section, and may be solid or tubular provided the selection allows for variable positioning of the support post  22  along the frame member  20 . A frame formed of round stock, either rod or tubing, is preferred because it then also may serve as an axle for each wheel. Other shapes of stock material will require additional, more costly, manufacturing steps to form the axles.  
         [0029]     Preferably, the first transverse section  26  is formed by making a right angle bend  30  in the longitudinal section  24  at a desired distance from one end thereof. Then the second transverse section  28  is welded preferably perpendicular to the longitudinal section  24  at its other end in a manner ensuring that the entire structure lays flat. Longitudinal section  24  and second transverse section  28  are welded together at a point where end  32  of second transverse section  28  is aligned with end  34  of the first transverse section  26 .  
         [0030]     There is a pair of wheels  36  rotatably attached to the second transverse section  28  and a single wheel  36  rotatably attached to the first transverse section  26 . The ends of the transverse sections are adapted to provide support axles on which the wheels  36  are mounted. Referring to  FIG. 1 , there is a pair of crimps  38  formed at each end of the transverse sections to provide stops for preventing inward axial movement of the wheels  36 . A washer  40  may be used to serve as a bearing surface against which the hub  37  of wheel  36  slides during rotation. End caps  42  are attached to the exposed ends of the transverse sections to keep the wheels  36  from falling off.  
         [0031]     Referring now also to  FIGS. 9, 10  and  11 , preferably a plate or base  44  is welded to the support post  22  to provide a means for attaching the support post  22  to the frame member  20 . The underside surface of plate  44  has two intersecting grooves  46  extending across the bottom of plate  44  to opposite ends of the plate to permit the support post  22  to be mounted in various locations and orientations to be described later. V-shaped grooves are preferred because of the relative ease in machining them. They also permit the support post  22  to self-align with the round stock material of frame member  20  and thus compensate for any manufacturing tolerances. In addition, making adjustments like placing the support post  22  at an angle with respect to a vertical axis in order to compensate for a special painting situation may be accomplished easily through the relative interaction between round stock material and V-shaped groove  46 .  
         [0032]     The support post  22  is removably attached to the frame member  20  with a plate  48  secured with a pair of releasable fasteners  50  (only one of which is shown). Plate  48 , together with base  44  and fasteners  50  form a clamp  51 . Preferably, the plate  48  extends diagonally across base  44  to increase the amount of surface contact between clamp  51  and frame member  20  for increased holding power. It will be apparent that the support post  22  may be positioned virtually anywhere on a straight portion of the frame member  20 . The support post  22  may also be positioned directly over the point of attachment of longitudinal section  24  and the transverse section  28 , in which case it is preferable to include an appropriately sized hole  45  ( FIG. 11 ) in the underside surface of base  44  at the intersection of grooves  46  to provide clearance for a weld bead which may project from the frame at the junction of sections  24  and  28 .  
         [0033]     There is a slot  56  in support post  22  to which a conventional airless spray gun  58  may be attached to the frame member  20  with means for adjusting the distance desired between the spray gun  58  and the surface to be painted. A spray gun extender  60  may be used to mount the spray gun  58  to the support post  22 . The spray gun extender  60  includes a remote trigger that attaches to the spray gun trigger and a handle for moving the cart by hand. Spray gun extender  60  is similar to an Outrigger gun pole, Product No. 757-920, available from Titan Tool, Inc., Oakland, N.J. Spray gun extender  60  generally differs from the Outrigger gun pole in that extender  60  utilizes a shorter two-piece pole and a different fastener adapted for mounting the extender to support post  22 . Spray gun extender  60  typically includes a spray gun holder  62 , top and bottom pole sections  64  and  66 , a control lever  68 , and a control cable  70 . An adjustable joint  72  having mating grooved faces  77  (see  FIG. 12 ) on the spray gun holder  62  allows a wide range of pivotable adjustments of spray gun  58  about a horizontal axis. Control cable  70  runs from the control lever  68  along or inside the pole sections  64  and  66  to a lever  74  pivotably mounted on the holder  62  for operating the spray gun  58 . When the spray gun  58  is mounted in the spray gun holder  62 , spray gun trigger  59  engages lever  74 . When the control lever  68  is pulled, control cable  70  transfers that movement to lever  74 , which in turn pulls the spray gun trigger  59  to begin spraying. Upon release of control lever  68 , a return spring  76  allows the paint valve in the spray gun  58  to close, by releasing the trigger  59  of the spray gun  58 . A fastener  78  attaches the end of the control cable  70  to the gun mount lever  74 .  
         [0034]     With reference to  FIG. 12 , spray gun holder  62  includes a main body  80 , a clamping block  82 , a clamping knob  84 , a gun support bracket  86  and a cable adjuster  88 . Initial setup includes placing the spray gun  58  into the gun support bracket  86  so that the spray gun trigger  59  rests on a bushing  90 . Knob  84  is then tightened until it comes to rest firmly against a handle of the spray gun  58 . The gun holder  62  is then attached to the support post  22  with a winged knob  92  (see  FIG. 8 ). The spray gun position is adjustable by loosening knob  92  and rotating the adjustable joint  72  or moving the gun and gun holder in slot  56  of the support post  22  to the desired position.  
         [0035]     It is to be understood that in the practice of the present invention, a pump (also not shown) acting as the external source of paint is located away from and is not mounted on the cart  18 . Mounting only the gun  58  and not the pump on the cart maintains the small size and maneuverability of the cart over prior art line stripers having the pump (and necessarily the prime mover for the pump, such as an internal combustion engine or electric motor) located on the cart. A flexible paint hose  94  provides a conduit for transferring paint from an external source (not shown) to the spray gun  58 .  
         [0036]     In operation, an operator uses the spray gun extender  60  as a handle to manually propel the cart  18  by pushing or pulling in the desired direction and at the same time actuating the control lever  68  to begin spraying a line on the pavement. The operator may use the longitudinal section  24  of the frame member  20  for line-up with a reference marker, such as a chalk line drawn on the surface or an existing line that is to be repainted, when striping long lines.  
         [0037]      FIG. 2  shows the present invention in an orientation that is generally preferred by a right-handed operator.  FIG. 3  shows a preferred setup for a left-handed operator. This of course is a matter of personal preference and in either case it merely requires flipping the cart over and reattaching the support post  22 , spray gun extender  60  and spray gun  58 .  
         [0038]      FIG. 4  shows the present invention in an orientation making the unit most suitable for painting angled lines such as in crosswalks. Placing the single wheel in front allows the spray gun to be brought close to a curb  75 .  
         [0039]      FIG. 5  is another view of the present invention and shows a preferred arrangement for painting a curb. In this orientation, the support post  22  may be rotated ninety degrees, as permitted by the intersecting grooves  46 , to a position that places the spray gun  58  perpendicular to the path of travel of cart  18 . This allows the operator to face the painted surface directly for better control. Making adjustments like placing the support post  22  at a desired angle with respect to the vertical axis, adjusting the gun holder  62  in slot  56 , and setting the adjustable joint  72  as may be necessary will allow the operator to spray both a vertical surface  71  and a horizontal surface  73  of a standard curb  75  at the same time.  
         [0040]      FIGS. 6 and 7  show yet another arrangement of the present invention and its versatility wherein it may be converted from a 3-wheel cart to a 2-wheel cart for spraying curved lines and circles. In this configuration, the cart  18  is rotated onto the wheels  36  that are supported by the second transverse section  28  once the support post  22  has been repositioned for this orientation.  
         [0041]     Although not shown in the drawings, it will be readily understood that owing to its lightweight construction, the cart can be easily lifted over a line once painted and placed in position to paint another line without the need to back it off the line, or run over the recently painted line with one of the wheels. The handle on pole  64  can also be used to rotate the cart onto the two in-line wheels, thus allowing the cart to be wheeled away from the recently painted line until the free wheel clears it and then the cart may be placed back on the ground.  
         [0042]     When it is desired to use the spray gun  58  for other purposes, it can be disengaged from the gun holder  62  for hand spraying.  
         [0043]     While the present invention has been described at some length and with some particularity with respect to the several described embodiments, it is not intended that it should be limited to any such particulars or embodiments or any particular embodiment, but it is to be construed with references to the appended claims so as to provide the broadest possible interpretation of such claims in view of the prior art and, therefore, to effectively encompass the intended scope of the invention. Furthermore, the foregoing describes the invention in terms of embodiments foreseen by the inventor for which an enabling description was available, notwithstanding that insubstantial modifications of the invention, not presently foreseen, may nonetheless represent equivalents thereto.

Summary:
An accessory cart having a J-shaped frame for removable mounting of a spray gun to convert a conventional airless paint sprayer into a line striper to paint lines on parking lots, curbs, warehouse floors and other pavement surfaces, and which can alternately be used in conjunction with a traditional line striper in cramped spaces or between parked cars, and which is easily converted from a 3-wheeled device to a 2-wheeled device for painting curved lines, and which permits adjustable positioning of the spray gun at a desired location on the cart to optimize the spray pattern in a particular application.