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BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to power tools for treating and shaping concrete. More particularly, the present invention relates to portable, hand operated power tools for shaping green concrete into curbs. 
     2. Description of the Related Art 
     Concrete curbs form structural borders upon peripheries of concrete streets or parking lots where aesthetics are important. Appropriate concrete curbing is often integral with gutter structures that contribute to proper drainage. Additionally, residential property owners often employ decorative edging along borders to enhance the appearance of their landscaping. Properly formed curb and gutter designs add valuable structural and functional attributes to modern concrete structures as well. In many communities properly designed curbs and gutter arrangements are required by zoning ordinances. 
     A wide variety of curb forming techniques thus exist. Concrete shaping systems and curb forming devices can contact freshly placed concrete directly, while still green in a slab, or concrete curbing can be extruded with a variety of placement devices. 
     Some large scale, motor driven curb forming devices store concrete in a hopper, and pump it outwardly through shaping dies, molds or extruder equipment that preshapes the curb. Some larger, wheeled systems used to strike-off or screed large slabs traverse forms or rails for support. Many include ancillary curb installers that shape slab edges as concrete is laid. 
     So-called slip-forming machines have been adapted to lay concrete curbing or curb and gutter arrangements during slab pouring and screeding. Typical slip forming machines follow the length of the slab and store wet concrete in a hopper. Concrete discharged from or forced out of the hopper is shaped by a form proximate the hopper that moves with the machine. As the form compresses and shapes the concrete edges, a properly shaped curb or curb and gutter combination is formed in place. 
     For example, U.S. Pat. No. 4,544,346 issued Oct. 1, 1985 illustrates curb forming apparatus associated with a screed. The screed treats plastic concrete and forms a curb along one or both sides of the slab as the screed travels the slab length. The triangular truss concrete screed has first and second sides supported by rollers which engage spaced apart forms. The screed traverses the entire width of the slab, and is supported upon forms, and is not hand operated by a single worker. A curb form is coupled to one side of the finishing machine. 
     U.S. Pat. No. 4,217,065 issued Aug. 12, 1980 discloses a slip-form curb and gutter machine with a wheeled chassis that travels along tracks. A concrete receiving hopper discharges green concrete that is shaped by suitable forms affixed to the chassis. A hand winch above the hopper attaches to a cable for pulling the machine along its tracks. An operator can stand on a platform disposed above the form. 
     U.S. Pat. No. 5,803,656 issued Sep. 8, 1998 discloses a motorized concrete screed with a roller attached to a chassis. A pair of handles extending from the chassis are independently adjustable. A throttle attached to one of the handles is electrically connected to the motor. A pair of wheel assemblies permit the apparatus to be easily moved to and from a worksite without damaging the roller. 
     Slip-form machines and large screeding devices involve expensive, heavyweight equipment, and they are too expensive and cumbersome for smaller contractors to set up and use economically, particularly on smaller jobs. Because of the disadvantages with large slip form machines and screeds, smaller hand operated machines have evolved for treating concrete and shaping it into gutters or curbs. Some use motor driven carriages that, like slip form machines, include hoppers that discharge concrete into molds or shapers that compress the concrete into a desired shape. Some analogous devices use a U-shaped handle arrangement, that journals a rotatable roller whose periphery contacts the concrete for shaping. 
     For example, U.S. Pat. No. 3,910,738 issued Oct. 7, 1975 discloses a concrete finishing roller rotatably mounted on an axle that is controlled by a handle. Indicia formed on the outer periphery of the roller imprints the concrete surface. Workers can manipulate the handle so that the roller may be pushed across green concrete. The depth of the impression made in the concrete surface may be varied by the addition or the removal of weights on the handle and by vibrating the roller in a vertical plane as it moves across the concrete surface. 
     U.S. Pat. No. 5,354,189 issued Oct. 11, 1994 discloses a concrete forming device for extruding curb, barrier, wall, gutter or the like from concrete or cement. Cement stored within a vibrating hopper falls onto tapered, counter rotating augers which compact and force the concrete through an adjacent extrusion mold for shaping. 
     U.S. Pat. No. 5,846,176 issued Dec. 8, 1998 also shows a hand-operated roller tool for concrete finishing. A hollow, cylindrical, roller secured journalled to a U-shaped frame has protrusions or nubs defined about its outer surface to produce a desired texture on the green concrete. A single worker can operate the device with a handle coupled to the frame. 
     U.S. Pat. No. 6,474,906 issued Nov. 5, 2002 discloses a concrete finishing machine wherein a roller extends between a primary motorized unit and a secondary unmotorized unit disposed on each side of a slab to be paved. An engaging lever must be pressed to initiate tube rotation, driving the primary and secondary units forward. 
     U.S. Pat. No. 6,863,470 issued Mar. 8, 2005 provides a curbing apparatus for shaping green concrete by pushing it through a channel defined by a mold. 
     U.S. Pat. Application No. 20020021938 published Feb. 21, 2002 discloses a curb forming and extruding machine includes a plunger that forces raw concrete via lower hopper into and through a curb extrusion mold. 
     U.S. Pat. No. 7,621,694 issued Nov. 24, 2009 discloses a curb forming machine using a single, rotatable curb-forming roller. A handle assembly is utilized for pulling and maneuvering the roller, and a motor rotates the roller to shape and smooth wet concrete into curbing. 
     U.S. Pat. No. 5,449,406 issued Sep. 12, 1995 discloses a machine for applying grout mortar to a tiled surface. A frustroconical shroud having a plurality of generally radially extending blades rotates about an axis that is perpendicular to the surface being treated. 
     U.S. Pat. Application No. 20050238745 discloses an apparatus for impressing three-dimensional patterns in a slip-formed concrete wall. Impression rollers include outer peripheries provided with three-dimensional patterns. One roller coats a side of an exposed wall, and an ancillary roller coats the top of the wall. 
     Despite the advantages of relatively recently develop portable curb forming devices, they suffer from well known disadvantages. Often they have to be made flush with available forms, and hand controlled designs with large rollers are difficult to guide and control. Irregular patterns and misshapen concrete edges can thus result. Changing the operating direction is difficult, because handles and frames, including wheeled carriages where used, are designed to move in only one direction. Further, where rollers are placed horizontally to help propel the apparatus, and rotate in an axis parallel with the plane of the slab, curb deformation and uneven spots can occur when the unit suddenly jerks in response to tight turns in smaller pours. 
     BRIEF SUMMARY OF THE INVENTION 
     This invention provides an improved, portable, hand controlled concrete curbing machine. Curb shaping is effectuated by a specially shaped head that rotates about an axis that is perpendicular to the slab. The head projects downwardly from a self propelled, wheeled carriage whose width and dimensions can be user adjusted or configured by the user to fit many diverse curbing applications faced by the small contractor. 
     The curb forming machine comprises a rectangular frame comprising inturned edges that slidably receive an adjustable subframe supporting a pair of wheels that can ride on a form. The subframe is user adjustable, so machine width can be selected to best fit the job application. A roller on the opposite frame side rides on the opposite curb form. Concrete is formed by a shaping head rotating beneath the frame driven by an electric motor. The motor is adjustably secured to the frame by a mounting plate secured beneath the frame by fasteners received within follower slots in the frame that slidably adjust position. 
     An optional, removable adaptor plate is disposed on an opposite frame end to support the machine when in transit or storage. It is removed for normal curb work. Te adaptor plate can raise the machine from for monolithic curbs without rebar by supporting the normal wheels, an effectively lowering them to ride o the ground. A roller behind the adaptor plate is exposed when the plate is removed, and it rides along forms when normal curb and gutter work is undertaken. Preferably the handle assembly is “offset” from the machine center to aid in operator control. 
     It is therefore a primary object of the present invention to provide a portable, one-man, self-propelled curb forming device that is ideal for smaller jobs. 
     It is also important to provide a curb-forming machine of the character described that is highly stable. 
     It is also an object to provide a transformable curb forming machine that can be user switched between jobs of different dimensions, and which can be switched between normal curb-and-gutter applications and monolithic curb jobs. 
     Another object is to provide a curb former of the character described that finishes and shapes plastic concrete and forms a curb with a desired size and shape. 
     Another important object is to enable contractors to use a single adjustable machine for either finishing normal curb and gutter work, or for finishing monolithic curbs. 
     A further object is to provide a powered, self propelled curb-forming apparatus which can easily be reversed in the direction of travel. 
     Another object of the present invention is to provide a motor-powered, curb-forming machine which is inexpensive, relatively lightweight, easy to use, and ideal for smaller contractors. 
     Yet another object is to provide a transformable curb and gutter machine that can be quickly and easily switched between job applications in the field without special tools or equipment. 
     These and other objects and advantages of the present invention, along with features of novelty appurtenant thereto, will appear or become apparent in the course of the following descriptive sections. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       In the following drawings, which form a part of the specification and which are to be construed in conjunction therewith, and in which like reference numerals have been employed throughout wherever possible to indicate like parts in the various views: 
         FIG. 1  is a rear isometric view showing the best mode of my new concrete curb forming machine; 
         FIG. 2  is a frontal isometric view thereof; 
         FIG. 3  is a rearward bottom isometric view thereof; 
         FIG. 4  is a partially exploded, fragmentary isometric view thereof, with portions thereof broken away for clarity or omitted for brevity; 
         FIG. 5  is an enlarged, partially exploded, fragmentary isometric view showing the preferred adjustable subframe and the wheels; 
         FIG. 6  is an enlarged, partially exploded, isometric view showing the preferred handle assembly; 
         FIG. 7A  is an enlarged, fragmentary, sectional view taken generally along line  7 - 7  of  FIG. 4 , with the adaptor plate removed, and showing the machine forming a curb and riding a two inch by six inch form on the left, and a two inch by twelve inch form on the right for normal curb and gutter work; 
         FIG. 7B  is an enlarged, fragmentary, sectional view similar to  FIG. 7A , with the adaptor plate removed, showing the machine in use with a monolithic curb with rebar; 
         FIG. 7C  is an enlarged, fragmentary, sectional view similar to  FIGS. 7A and 7B , with the adaptor plate removed, showing the machine in use with a monolithic curb without rebar; 
         FIG. 8  is an enlarged, partially exploded, fragmentary isometric view showing the adaptor plate end of the frame; and, 
         FIG. 9  is a rear elevational view thereof. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With initial reference directed now to  FIGS. 1-3  and  9  of the appended drawings, a concrete curb forming machine constructed generally in accordance with the best mode of the invention has been generally designated by the reference numeral  10 . The curb former machine  10  is adapted to traverse wet or freshly laid concrete, preferably disposed between parallel and slightly elevated forms, for shaping edges or boundary regions of the slab into arcuate curbs of appropriate shape and dimensions. The machine  10  can be used by a single workman, and it is portable, enabling quick transportation between job sites. 
     The curb forming machine comprises a rigid, generally rectangular frame  12  somewhat in the form of a flat parallelepiped. The frame  12  has downwardly depending front and rear edges  14  ( FIG. 1) and 16  ( FIG. 2 ) respectively. (Since the handle can be adjusted to face either direction, these edges  14  and  16  can each be referred to as either “font” or rear.“) Various components are mounted on the upper surface  18  ( FIGS. 1 ,  2 ,  5 ) atop the frame  12 . A handle assembly  20  is pivotally and adjustably mounted to the frame  12  at opposite frame ends, as will later be described in detail. An electric drive motor  22  ( FIGS. 1 ,  2 ) secured to frame  12  is powered by a conventional electrical cord  24  ( FIGS. 1 ,  2 ) that is secured to the handle assembly  20  and controlled by a conventional switch  25 . Conventional 120 V.A.C. power is supplied by plug  27 . 
     As described in detail hereinafter, a rigid, subframe  30  supporting a pair of main wheels  32  is adjustably, slidably coupled to the right side of the frame  12 . In use, these wheels normally ride on a two inch by six inch toe board form, which is used in normal curb and gutter work. The opposite end of the frame supports a removable and adjustable adaptor plate  36  ( FIGS. 2 ,  3 ) that normally supports the machine  10  when not in use. 
     Concrete is contacted by and formed by a replaceable shaping head  40  operationally disposed beneath frame  12 . Motor  22  is amounted atop frame  12  proximate surface  18 . As best seen in  FIGS. 3 and 4 , the shaping head  40  is a hollow, hat-like structure, preferably molded from plastic. Head  40  has a body  41  ( FIG. 3 ) substantially shaped like an inverted, truncated cone, and an integral, convex cap portion  42  that projects downwardly. An integral, circular ridge portion  44  transitions between body  41  and an integral, ring shaped flange  45  that includes a plurality of radially spaced-apart mounting orifices  46  ( FIG. 4 ). A circular drive plate  48  above head  40  is concentrically secured to flange  45  on head  40  by fasteners  49  that penetrate orifices  50  and the aligned orifices  46  in head flange  45 . Plate  48  has a central, cylindrical drive hub  52  that is reinforced by a plurality of webs  54 . 
     A rigid, square motor mounting plate  55  above drive plate  48  has a central orifice  56  through which hub  52  rotatably projects. The hub key orifice  53  is penetrated by motor output shaft  58  ( FIG. 4 ) that is coaxially aligned with orifices  53  and  56  and hub  52 . Shaft  58  thus establishes an axis of rotation for itself and the shaping head  40  that is perpendicular to the slab surface. Motor  22  is attached to mounting plate  55  with suitable fasteners (not shown) that penetrate orifices  59  in mounting plate  55  ( FIG. 4 ). Importantly, motor mounting plate  55  can be adjusted lengthwise across frame  12  (i.e., towards or away from the ends of the machine frame  12 . To this effect there are a plurality of standoffs  60  ( FIG. 4 ) that project upwardly, generally from the corners of mounting plate  55 , and register with elongated adjustment slots  62  defined in the surface  18  of frame  12 . Suitable fasteners  64  ( FIG. 1 ) penetrate frame adjustment slots  62  and secure the head  40  and motor  22  in a desired position. Widthwise adjustment in head placement is thus possible, by loosening fasteners  64 , shifting the motor and the head  40  below along the frame  12 , and then retightening the fasteners  64 . 
     With joint reference now to  FIGS. 5 and 6 , the preferred subframe  30  is also adjustably attached to the frame  12 . The edges  14 ,  16  of the frame  12  have inwardly turned lip portions  66  ( FIG. 5 ), forming a generally C-shaped cross section. Subframe  30  has a generally rectangular top  68 , bounded by spaced apart, parallel end rails  69 ,  70 , that ride within and are captivated between frame edges  14  and  16  in assembly ( FIG. 5 ). A subframe reinforcement  71  extends between a side strut  73  and a generally U-shaped wheel mounting plate  75 . The main wheels  32  previously described can be secured to plate  75  with bolts  77  that penetrate the wheels and mounting orifices  78  in plate  75 , being secured with nuts  79 . Preferably there are elongated mounting slots  81  formed in the legs of plate  75  above wheel orifices  78  that slidably accommodate extra large wheels for clearance where necessary. 
     Subframe  30  is moved relative to frame  12  by a hand-operated adjustment knob  84 . As seen in  FIG. 5  for example, there is a U-shaped flange  86  projecting upwardly from the end of frame  12 . An elliptical orifice  82  ( FIGS. 2 ,  4 ,  5 ) in the arcuate flange  86  provides a connection point for lifting. One end of a threaded shaft  88  ( FIG. 7A ) penetrates flange  86  and is secured to drive knob  84 , and the opposite end rotatably terminates in an L-bracket  90  ( FIG. 7A ) that is secured to frame surface  18  by a fastener  91 . A downwardly projecting traveler  93  has a threaded collar  94  threadably mated to shaft  88 , so that rotation of the knob  84  moves the traveler  93 . The lower shank  96  of the traveler  93  penetrates an elongated slot  98  ( FIGS. 4 ,  5 ) formed in frame  12 , and is attached to subframe  30  to move main wheels  32  inwardly or outwardly relative to the motor  22 . Specifically, traveler shank  96  penetrates and is fastened to a selected orifice  99  ( FIG. 5 ) in the subframe reinforcement strut  71 . Thus the main wheels  32  can be move inwardly or outwardly to change or adjust the effective width of the curb former  10 , adapting it for use in diverse situations of varying dimensions and width. 
     With reference now to  FIGS. 1 ,  2  and  8 ,  9 , there is an adaptor plate  36  disposed on the frame end  101  ( FIGS. 2 ,  8 ) opposite wheels  32 . The adaptor plate  36  is shaped generally “U-shaped” and when installed, it is mated to a bell shaped plate  102  ( FIG. 8 ) secured at end  101  of the frame  12  ( FIG. 8 ). Plate  102  has a curved top  104  bordering a curved follower slot  105  that is used by the handle assembly  20 , as later described. A plurality of threaded studs  107  projecting outwardly from the plate  102  ( FIG. 8 ) penetrate upper orifices  109  and aligned slots  111  in the legs  110  of adaptor plate  36 . Hand-operable wing nuts  114  engage studs  107  to secure adaptor plate  36  to bell shaped plate  102 . The elliptical orifice  103  provides a lifting point when used with similar orifice  82  in flange  86  ( FIG. 4 ). Optional wheels can be attached to plate  36  with orifices  112 . 
     The bell-shaped plate  102  also mounts a roller  120  ( FIGS. 7A ,  8 ) that is used with normal curb and gutter work with adaptor plate  36  removed from the machine. Roller  120  is secured to stud  122  on bell shaped plate  102 , being journalled with bearing  124  and fastener  125  ( FIG. 8 . 
     The adaptor plate  36  has several functions. First, as illustrated in  FIGS. 1 and 2  it supports the machine in a stable position for transportation or stowage. It is removed in use (i.e.,  FIG. 7A ) for normal curb and gutter work. Finally, it can be raised or adjusted in position to support an auxiliary wheel for monolithic curb installations, (i.e.,  FIG. 7B ). 
     The handle assembly  20  can tilt in either direction, fore or aft of the motor  22 , so that the curbing machine is easily reversible, from the point of reference of an operator, who pushes” forwardly” along an intended direction of travel with the handle assembly  20 . As best appreciated from  FIGS. 1 ,  2 ,  6 , and  9 , the handle assembly is “offset,” in that the handlebar  127  and hand grips  128  are positioned towards the adaptor plate side  101 , away from the motor  22 . As best seen in  FIG. 9 , the handle assembly comprises an angled rod  130  extending angularly upwardly from a turned end portion  132  that is penetrated by shaft  88  ( FIGS. 7A and 9 ) and rotatably secured within pivot bracket  134  ( FIG. 9 ). A vertical handle portion  136  extends downwardly from junction  138 , where it connects to handle rod  130 , to another pivot bracket  138  ( FIG. 7A ) within which end  137  ( FIG. 6 ) is journalled by pin  140  ( FIG. 7A ) and secured by fastener  142 . The handle orientation is fixed by tightening an adjustment knob  144  that is threaded to carriage bolt  145  ( FIG. 7A ) that penetrates and tracks within follower slot  105  in bell-shaped plate  102  previously described. The head  147  ( FIG. 7A ) of carriage bolt  145  prevents axial escape of the bolt and insures proper tracking within the follower slot. 
       FIGS. 7A and 7B  illustrate actual use. In  FIG. 7A  the wheels  32  are riding upon a two-by-six inch toe board  150  that is substantially parallel with and spaced-apart from a two-by-twelve form member  152 . Shaping head  40  penetrates downwardly into the concrete  153  and a concrete mass  154  is shaped by the rotating head  40  that creates a curb between itself and the form  152 . It will be noted that for normal curb and gutter work, the adaptor plate  36  previously discussed has been removed, exposing the roller  120  mounted to plate  102  ( FIG. 8 ) that rides atop form member  152 . It should be appreciated that the head  40  is removable and selectable; differently shaped heads can be used for differently shaped curbs. 
     In  FIG. 7B  a monolithic curb is being formed. Here roller  120  rides atop a form member  161 . Adaptor plate  36  is uninstalled. Within the raw concrete are rebar chairs  162  and a rebar mat  164 . A form member  167  ( FIG. 7B ) contacts the rebar mat  164  and supports wheels  32 . 
     In  FIG. 7C  a monolithic curb without rebar is being formed. Here roller  120  rides atop a higher form member  169 . Adaptor plate  36  is uninstalled from frame side  101  and placed on the opposite, “wheeled” side. Wheels  32  ride directly on surface  171 , without a form on the left side ( FIG. 7C ). Referencing  FIG. 5 , for the application of  FIG. 7C , the wheels  32  may need to be elevated. To do this they are removed from plate  75  and attached to adaptor plate  36 . With the adaptor plate  36  removed from side  101  (i.e., exposing roller  120 ) and coupled instead to wheel mounting plate  75  (i.e.,  FIG. 5 ) to form an extension as shown, ( FIG. 7C ), machine  10  easily traverses the work site surface  171  without a form on the left (i.e., like form  152  in  FIG. 7A  or form  167  in  FIG. 7B ) that are no longer needed. 
     From the foregoing, it will be seen that this invention is one well adapted to obtain all the ends and objects herein set forth, together with other advantages which are inherent to the structure. 
     It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims. 
     As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Summary:
A hand-controlled, curb forming machine that is transformable between different widths and geometries, and between different wheel configurations, to accommodate different concrete curbing. A downwardly projecting, rotating head that rotates about an axis perpendicular to the slab shapes raw concrete into appropriately styled and contoured curbs. A machine frame slidably receives an adjustable, wheeled subframe. A roller on the opposite frame side rides on an opposite curb form. A pivoted handle is reversible. The electric motor is adjustably secured to the frame by a mounting plate movable within follower slots in the frame. A removable adaptor plate disposed on an opposite frame end supports the machine when not in use, but can be removed for normal curb work exposing a form riding roller. When the machine is deployed with monolithic curbs without rebar, the adaptor plate can mount to the subframe to raise the machine by lowering the wheels.