Abstract:
A cart is provided for transport of material, such as tools, equipment, supplies and the like on curved surface roofs of a building or other structure which as a varying or changing slope. The cart has a base frame mounted on rear wheels and forward casters. The base frame attaches by a rope or cable to an anchor point on the roof. An equipment basket is suspended at pivot points between supports extending above the base frame. The basket and its contents thus remain in a level, stable position on the roof as the cart is moved to various locations over the curved roof surface during use.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a cart for transport of tools, supplies, equipment, and other material over a curved surface in connection with work on that surface.  
           [0003]    2. Description of the Related Art  
           [0004]    There are buildings and other types of structures which have a curved roof or upper surface which changes in shape over its downward extent or slope, often as well across its lateral extent or span. An example with which applicant is familiar is the generally dome-shaped roof of a reactor containment building at an electrical power generating facility. Upper portions of this curved roof or surface are often on the order of two hundred feet or so, or even more, above the earth&#39;s surface in the nearby area.  
           [0005]    From time to time, repairs, maintenance or inspections must be made on the surface of this type of curved roof surface. This required equipment and tools for the service crew. The service crewmembers had need for several types of equipment and tools while working on the roof, and the equipment not in use had to be safely stored. Clearly a loose object falling several hundred feet from the roof was a major safety hazard.  
           [0006]    However, the tools and equipment had to be kept available on the roof by the service crew as needs arose to use them. Further, the service crewmembers needed their hands and arms free for work purposes. Each service crewmember for safety reasons wore a safety harness attached by a cable or rope to a connection at the top of the roof.  
           [0007]    There were competing demands on service crews to be able to work easily and quickly on these elevated, irregular-shaped work safely, surfaces and yet have tools and equipment readily at hand. One possible approach was to have additional work crewmembers assigned to provide and hold the tools and equipment. This solution increased the number of workers in a relatively risky locale and could give rise to safety concerns.  
           [0008]    So far as is known, carts for general transport of items over flat or planar surfaces did not lend themselves to use on curved surfaces of roofs and the like. Stability of the cart on the curved surface was one concern, while ease of movement of these types of general transport carts over the curved surface was another. Carts adapted for transport or storage of special items of equipment or cargo on flat or planar surfaces suffered from the same concerns.  
         SUMMARY OF THE INVENTION  
         [0009]    Briefly, the present invention provides a new and improved cart for transport of materials over a curved or non-planar roof or similar surface of a building or other structure.  
           [0010]    The cart includes a base frame and a material basket for receiving the material to be used on the surface. The base frame is connectable to the building and has transport wheels for movement of the cart over the surface. The transport wheels include a set of casters located in the base frame for multidirectional movement of the cart over the surface. The transport wheels also include a set of roller wheels for movement of the cart vertically over the surface. The material basket is movable with respect to the base frame and remains in a horizontal position as the base frame moves over the surface.  
           [0011]    The material basket thus remains in a horizontal or level position with respect to the curved surface as the cart is moved over the surface. Material received in the basket is thus retained in the basket and the likelihood of it falling out of the basket because the base frame changes position due to the curved surface is greatly reduced. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is an isometric view of a material cart according to the present invention.  
         [0013]    [0013]FIG. 2 is another isometric view of the material cart of FIG. 1.  
         [0014]    [0014]FIG. 3 is a front elevation view of the material cart of FIG. 1.  
         [0015]    [0015]FIG. 4 is a side elevation view of the material cart of FIG. 1.  
         [0016]    [0016]FIG. 5 is a top view of the material cart of FIG. 1.  
         [0017]    [0017]FIG. 6 is a partially exploded isometric view of a portion of the material cart of FIG. 1. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]    In the drawings, the letter T designates generally a transport cart for transport of material over a curved surface S (FIG. 2) of a building or other structure, such as a roof. The surface S is a curved roof or upper surface which changes its shape in a vertical plane indicated by an arrow V as well as in a lateral plane indicated by an arrow L. In one embodiment, the surface S is a generally dome-shaped roof of a reactor containment building at a nuclear-powered electric power generation facility. Such a surface as the surface S can be on the order of approximately two hundred feet above ground level.  
         [0019]    Periodically, maintenance or service crews must install or repair items on the surface S. Examples of such items which can be installed or repaired are grounding rods and mounting tripods or bases for such rods. It should be understood that other types of items located on the surface S may also need from time to time to be installed or repaired. The transport cart T is used to provide storage and movement of materials for use by service crews at such times. The materials may be tools, supplies, equipment and other items. A wide variety of materials may be stored and moved with the transport cart T of the present invention. For example, the cart T may be used to transport and store: wrenches; nut drivers; pliers; power drills; containers of nuts, bolts, or other fasteners; lubricant containers or spray cans; couplings and bases for equipment to be installed; and other similar types of materials. Further, equipment to be installed on or removed from the surfaces may also be transported and stored in or on transport cart T. The particular types of materials depend upon the nature of the work to be performed on the surface S. The transport cart T is moved onto the surface S through a conventional axis portal or door present on the roof. Typically, one or more anchor mechanisms are provided at the access portal through which service crewmembers attach their safety harnesses by means of a retainer cable or rope.  
         [0020]    Considering the transport cart T in more detail, the cart T includes a base frame F and a material basket B for receiving the material to be used on the surface S. The material basket B is movable with respect to the base frame F yet remains in a horizontal position with respect to the ground level as the base frame F moves over the surface S. The base frame F is connected to one of the anchor points on the building by an attachment rope or cable (not shown). The attachment rope may be tied to the frame F at one or more, preferably two, or alternatively one or more connector hooks or rings may be provided for attachment of such a rope or cable.  
         [0021]    The base frame F is a generally rectangular structure including a front bar or frame member  10  to which the attachment rope or cable is connected. Two side frame members  12  extend rearwardly from the front frame member  10  to a rear frame  14 . The frame members  10 ,  12  and  14  may be channel members, beams, cylindrical or rectangular tubes or solid rods or bars, as desired.  
         [0022]    Transport wheels W are provided with the frame F for movement of the cart T over the surface or roof S. The movement of the cart T is multi-directional in that the cart T may move freely vertically in the plane V and laterally in the plane L over the changing contours of the roof S as required by service crews during use. A crewmember by exerting a pulling force on the attachment cable or rope is able to cause such movement. Typically, small obstacles such as small connector bolts and grounding grid wires are present on the roof S. The transport wheels W also are sufficiently large to allow the cart T to move smoothly over such small obstacles.  
         [0023]    The wheels W include a set of casters C located on an upper portion of the base frame F near the front frame member  10  to afford lateral and vertical, and thus multi-directional movement of the cart T over the surface S. The casters C are preferably mounted at junctures  18  of the front frame member  10  with the side frame members  12  and are freely rotatably moveable in a plane defined by the base frame F. The caster wheels C include a yoke or housing  20  in which wheels  22  are rotatably movable in a plane perpendicular to the plane of the base frame F.  
         [0024]    The yokes or housings  20  in which the caster wheels  22  are, as has been set forth, freely rotatably movable with respect to the base frame F so that the caster wheels  22  may guide the transport cart T both laterally and vertically in response to forces exerted by the service crew members to move the cart T by use of the attachment cable or rope or otherwise.  
         [0025]    The support wheels W also include a pair or rear wheels R located near the rear frame member  14 . The rear wheels R take the form of roller wheels  26  rotatable in the vertical plane V for movement of the cart vertically in the vertical plane V up and down the surface S. The roller wheels  26  may be larger than the caster wheels  22 , as shown, or they may be of like size, if desired. The roller wheels  26  are suitably mounted to side frame members  12  at or near the rear frame member  14  for rotational movement. The roller wheels  26  are mounted on an axle  30  or shaft pin to rotate about an axis generally parallel with the rear frame member  14 . The axis of rotation of the rear roller wheels  26  may be along a common laterally extending axle  30  parallel with the frame member  14  as shown. Each of the roller wheels  26  is fitted for rotational movement to an outer end  30   a  at each end of the axle  30  which extends through a bearing or sleeve  27  (FIG. 6) in a yoke or lug  28  mounted on side frame member  12 . It should be understood that each roller wheel  26  may be individually provided with a separate shaft pin for rotational support instead of being provided with a common axle  30 .  
         [0026]    It should also be understood that in some cases, the rear or lower set R of wheels may be caster wheels in place of roller wheels for greater freedom of movement, if desired.  
         [0027]    The material basket B is movably mounted to the base frame F to remain in a horizontal position with respect to ground level as the base frame F moves over the surface S despite variations in the curvature and shape of the surface S. The material basket B has a lower frame  40  composed of four side members  42 ,  44 ,  46  and  48  defining a rectangular frame. The side members  42 ,  44 ,  46  and  48  may be angle members, channels, beams or rods, as desired. A mesh or screen or expended bar sheet or other suitable material is mounted extending between the four side members  42 ,  44 ,  46  and  48  to form a bottom surface  50  of the material basket B. If desired, the bottom surface  50  may be a continuous sheet of metal, wood or other suitable material.  
         [0028]    Four uprights or weights  52  are formed at each corner of the bottom frame of the material basket B extending upwardly. A sheet of mesh, screen or other suitable material  54  is mounted to extend between each pair of uprights  52  to form side walls  56  of the material basket B. Again, the side walls  56  may be of a continuous panel or sheet of material if desired. Top edge members  58  are mounted to extend between each adjacent set of uprights  52  above the side walls  56  to define upper edges of the material basket B. The uprights  50  and the edge members  58  may be formed of the structural materials like those suitable for use on side members of the lower frame  50 . If desired attachment clips, hooks or other suitable attachment or connector members may be mounted on the base frame F or the material Basket B to provide connector locations for materials or items which do not readily fit into the basket B.  
         [0029]    Connector bars or beams  60  are mounted with the side walls  56  extending from the front to the rear of the material basket B and have outwardly extending rods or shafts  62  mounted at the center portions thereof along the length of their extent. The rods or shafts  62  arte freely rotatably movable in connector openings  64  formed in the upper end  66  of a support member  70  of the base frame F. The support member  70  is a vertically upstanding member, one of which is mounted at end  72  on one of the side members  12 , typically approximately one quarter of the length of the side frame member  12  from the rear frame  14  to the front frame  10 . Support struts  74  are mounted extending upwardly from the side members  12  near the rear frame  14  for connection at a suitable height on the uprights  70  for support of the upright  70  and for load bearing purposes.  
         [0030]    In the operation of the present invention the service crew loads materials into the basket B and the cart T. The cart is then attached to the building and placed on the surface S. The cart T may be lowered vertically over the surface S because of the rear wheels R.  
         [0031]    The cart T is also capable of multidimensional movement, both laterally and vertically, due to the caster wheels C. As the cart T moves over the curved surface S, the material basket B remains in a level or horizontal position because of its pivoted connection to the support members  70  if the base frame F.  
         [0032]    In this way, the risk of materials falling from or slipping out of the basket B is materially reduced. Further, the center of gravity of the cart T remains below the rods  62 . Thus the likelihood of the cart T falling or tilting because of imbalance is also reduced.  
         [0033]    The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials, and components, as well as in the details of the illustrated construction may be made without departing from the spirit of the invention.