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BACKGROUND OF THE INVENTION 
     The present invention relates to a surface preparation apparatus (SPA) for asphalt, concrete and other road surfaces, and in particular to a surface preparation apparatus which can be towed by various vehicles, which can be offset with respect to the direction of towing, and which can be adjusted in three axes. The preferred SPA is an asphalt reclaiming unit for being towed behind a truck of other prime mover. 
     Road surfaces, particularly asphalt road surfaces form a majority of road surfaces in the United States. Asphalt is also used in other applications, such as parking lots, biking paths and walking paths. A problem with asphalt is that is has a limited, useful life. When that useful life has been exceeded, the surface must be replaced or rehabilitated. Often, it is not desirable or cost effective to rehabilitate the entire road surface, particularly when only portions or segments of a paved section have deteriorated. As a result, the road surface is allowed to continue to deteriorate until use of a conventional full surface resurfacing unit becomes cost effective. The need to wait until the use of conventional resurfacing units becomes cost effective, results in temporary repairs such as patching, which are not as desirable as resurfacing. However, without a more cost effective manner resurfacing small areas, or portions of larger areas, resurfacing which might otherwise be completed if smaller, more flexible resurfacing units were available, will be delayed. Furthermore, there will be a tendency to redo surfaces which might not need to be done because only larger areas can be accommodated by the larger conventional units. Conventional units tend to be very large and heavy. They are often self propelled or attached to existing vehicle frames. The power for such units is generally supplied by one unit which means that some of the power is used to drive the vehicle and some of the power is used in the surface treatment apparatus. For this reason, those units are very slow. In addition, they can only be used to resurface large areas. It will be appreciated, therefore, that a need exists for a device for moving at greater speeds and preparing on a variety of surfaces such as shoulders, crowns, transitions, pipe lines, pot holes and the like. 
     Accordingly, it will be appreciated that there is a need for an efficient way of resurfacing asphalt, concrete and other surfaces used for roadways, walkways, parking lots and the like. The present invention provides advantages over the prior devices and the prior methods used to resurface these and other surfaces, and also offers other advantages over the prior art and solves other problems associated therewith. 
     SUMMARY OF THE INVENTION 
     The surface preparation apparatus of the present invention is compact, easily transportable, and includes a surface treatment unit which has a surface modifier or “cutter drum” powered by its own power source. The apparatus includes transport/support wheels and a tow bar pivotally interconnected with the surface treatment unit so that it may be towed by a truck or other vehicle having an independent power source. The surface treatment unit has a longitudinal axis and a transverse axis, with the longitudinal axis being perpendicular to the direction in which the units is towed (towing direction), and the transverse axis is coincident with the towing direction. The cutter drum has a rotational axis and is contained within the surface treatment unit and arranged such that the rotational axis is parallel to the longitudinal axis of the surface treatment unit. The surface modifier or cutter drum is preferably off-set relative to the transverse axis of the surface treatment unit such that the surface modifier operates substantially to one side of the surface treatment unit. The surface treatment unit is pivotally attached to the tow bar to enable the surface modifier to operate adjacent edges of a surface to be treated e.g., the shoulder of a road surface or the like. The height and sideways tilt of the surface treatment unit may be adjusted as desired to produce surface profiles of different configurations where the depth of the “cut” or the angle of the “cut” are varied. 
     One objective of the present invention is to provide a surface preparation apparatus which may be towed by various types of vehicles at a broader range of speeds than those which are possible with a conventional surface treatment unit. 
     Another objective is to create a compact surface preparation apparatus which is easily transported between locations. 
     Yet another objective is to concentrate weight and power on or to a surface modifier or “cutter drum”. 
     A further objective of the present invention is to provide a surface preparation apparatus which rehabilitates surfaces at a high rate of speed. 
     Another objective of the present invention is to provide a surface preparation apparatus which is easily oriented in different directions with respect to a surface to be prepared. 
     Still another objective is remote control of a surface treatment apparatus by an individual. 
     A still further objective is to rehabilitate surfaces of various widths and compositions. 
     Another objective is to reduce the potential of injury due to flying debris. 
    
    
     These and various other advantages and features of novelty that characterize the present invention are pointed out with particularity in the claims annexed hereto informing a part hereof. However, for a better understanding of the present invention, its advantages and other objects obtained by its use, reference should be made to the drawings, which form a further part hereof and to the accompanying descriptive matter, in which there is illustrated and described preferred embodiments of the present invention. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be further described in connection with the accompanying drawings, in which: 
     FIG. 1 is a side view of the preferred surface treatment apparatus of the present invention pivotally interconnected with a prime mover (shown in hidden lines); 
     FIG. 2 is a perspective view the surface treatment unit shown in FIG. 1; 
     FIG. 3 is a right side elevation of the surface treatment unit shown in FIG. 1 in an elevated position; 
     FIG. 4 is a front elevation of the surface treatment unit shown in FIG. 3; 
     FIG. 5 is a left side elevation of the surface treatment unit shown in FIG. 3 in a raised position; 
     FIG. 6 is a rear elevation of the surface treatment unit shown in FIG. 5; 
     FIG. 7A is a schematic view of the left side of a lift unit of the surface treatment unit of FIG. 1 in an raised position; 
     FIG. 7B is a schematic view of the left side of the lift unit of FIG. 1 of the surface treatment unit in a lowered position; 
     FIGS.  8 A- 8 C are schematic end views of the tilt mechanism of the surface treatment unit of FIG. 1 in vertical, left and right orientations, respectfully; 
     FIG. 9 is a partial rear schematic views of the surface modifier or “cutter drum” and the support wheels of the surface treatment unit of FIG.  1 . 
     FIG. 10 is a schematic view of a “cutter drum” or surface modifier of the present invention in relation to a surface to be prepared; 
     FIGS.  11 A- 11 C are schematic top views depicting the tow bar attached to the surface treatment unit of FIG. 1 in normal, left and right orientations, respectively; 
     FIG. 12 is a schematic side elevation of an alternate surface treatment apparatus having a horizontally pivotal tow bar and a front axle wheel assembly to reduce the weight on the prime mover; and 
     FIG. 13 is a top schematic view of the alternate embodiment shown in FIG.  12 . 
    
    
     DETAILED DESCRIPTION 
     Referring now to FIGS.  1 - 13 , the surface preparation apparatus  10  of the present invention is generally shown in the FIG.  1 . The surface preparation apparatus  10  includes a tow bar  12 , a surface treatment unit  22  having a support mechanism  150 . The tow bar  12  has first and second ends  14 ,  16 . The first end  14  of the tow bar  12  is attached to a tow bar adaptor  18  or an extension  18  of the tow bar  12  which is pivotally connected to a tow vehicle or prime mover V. The second end  16  of the tow bar  12  fixedly secured to an extension  108 . The tow bar  12  and the extension  108  are pivotally interconnected with the surface treatment unit  22  at a pivot point  120  behind a rotational axis  330  of a cutter drum  82  with respect to forward movement of the surface treatment unit  22  when pulled in a forward direction by the prime mover V. The first end  14  of the tow bar  12  is equipped with a jack  20  to assist in attachment and removal of tow bar  12  from a prime mover or tow vehicle V. In an alternate embodiment, the jack  20  may be supplanted with a wheeled support assembly  21 ′, shown in FIGS.  12 - 13 , to reduce the amount of weight supported by a tow vehicle or prime mover V′. In the alternate, embodiments of the apparatus  10 ′ shown in FIGS. 12 and 13, the tow bar  12 ′ includes two separate bars  12   a ′,  12   b ′ pivotally interconnected as shown. 
     The preferred surface preparation apparatus  10  is provided with a plurality of actuators which transmit power in a generally linear fashion. The preferred actuations are hydraulic cylinders, but other actuators, including but is not limited to pneumatic cylinders, linear motors, linear screws and the like may be used. In preferred embodiments such as that shown in FIGS.  1 - 11 C, the actuators are hydraulic cylinders  132 ,  134 ,  202 ,  204 ,  214 ,  216 . 
     In FIG. 1, the first end  14  of tow bar  12  is attached to a tow bar adaptor  18  which is in turn removably attached to a prime mover or tow vehicle V. Although the prime mover V as depicted in hidden lines in FIG. 1 is in the outline of a pickup truck, it is understood that other vehicles such as dump trucks, tractors, road graders, or the like may be utilized without departing from the spirit and scope of the invention. For example, if the surface treatment apparatus  10  is towed by another vehicle such as a dump truck or road grader, the tow bar adaptor  18  would be omitted and other mechanisms, known in the art for attaching towed units to towing vehicles, would be used. The surface preparation apparatus  10  also includes a remote control and monitor unit  24  which enable a person in the cab of a tow vehicle to control the surface preparation apparatus  10 . The remote control and monitor unit  24  is electrically connected to the various actuators of the surface preparation apparatus  10  by electrical wiring within cable  26 . 
     The surface treatment unit  22  of the preferred embodiment includes a housing  28  with an upper section  42  and a lower section  44 . The preferred surface modifier is a cutter drum  82  contained within the lower section  44  of housing  28 . The cutter drum  82  includes a plurality of cutter teeth  84  conventional to the art. Although the preferred surface modifier is a cutter drum as depicted in the FIGS.  3 - 11 , it is understood that other surface modifiers known to the art may be utilized without departing from the spirit and scope of the invention. The cutter drum  82  is rotatably connected to a conventional power source or motor (not shown) which is contained within the upper section  42  of housing  28 . In preferred embodiments the power source is a standard Caterpillar® 3056 engine which is a turbo changed, after cooled, inline 6 cylinder diesel 180 hp engine. The preferred clutch in an SAE#3, Rockford or equal, engine mounted. In other embodiments, having greater horse power, either 260 hp Caterpillar® 3126 engine can be used with a SAE#1 clutch, or a John Deere 6081A 275 hp engine with the SAE#1 clutch. 
     A support mechanism  150  is attached to, and extends rearwardly from the rear side  36  of housing  28 . The support mechanism  150  includes a lift unit  188 , a tilt mechanism  206 , and support wheels  186 . 
     Referring now especially to FIGS.  2 - 6  and  8 A- 11 C the surface treatment unit  22  will be described in greater detail. Starting with a perspective view of the surface treatment unit  22 , surface treatment unit  22  is generally rectangular with a length having a longitudinal axis L and a width having a transverse axis TV. The surface treatment unit  22  is oriented such that the longitudinal axis L of the surface treatment unit  22  is generally perpendicular to towing direction T (not shown). The surface treatment unit  22  comprises a housing  28  having an upper section  42  and a lower section  44 , with a power source located within the upper section and a surface modifier located within the lower section. The surface modifier has a rotational axis  230  which is parallel with the longitudinal axis L of the surface treatment unit  22 . The cutter drum  82  extends only partially along the width of the surface treatment unit  22  which extends along the longitudinal axis L, and preferably is offset or located to one side with respect to the transverse axis TV of the surface treatment unit  22 . This arrangement enables the cutter drum  82  to treat those surfaces to one side of the line of force defined by the towing direction T. Preferably the cutter drum  82  is located to the right of the transverse axis TV the surface treatment unit  22 , but it will be understood that the cutter drum  82  may be located to the left of the transverse axis TV of the surface treatment unit  22 , or even be centrally located with respect to the transverse axis TV without departing from the spirit and scope of the invention. 
     In the preferred embodiments, the surface treatment unit (STU)  22  will follow the prime mover V in a following direction F which is parallel with the transverse axis TV of the surface treatment unit  22  and perpendicular to the longitudinal axis L and the rotational axis  230  of the cutter drum  82 . When the prime mover V drawing the surface treatment unit  22  is traveling in a straight line, and the surface treatment  22  is offset to the left or right as shown in FIGS. 11B and 11C, the towing direction T and the following direction F will always be parallel with one another, because the hydraulic cylinders  132 ,  134  drive the STU  22  to one side or the other, but maintain this orientation so that the cutter drum  82  will cut in a straight and consistent path. 
     The front side  30  of lower section  44  of housing  28  includes a front debris shield  50  which serves to contain fragments of surface material dislodged by cutter drum  82  within housing  28 . Front debris shield  50  is slideably mounted to housing  28  by pins  60  which pass through two parallel slots  52  which are sized to admit the pins  60 . The front debris shield  50  is retained on the pins  60  by washers  62  and retainers  64  which are removably attached to the pins  60 , preferably threadably attached. The front debris shield  50  includes a bracket  54  which supports a surface follower  56 . The surface follower  56  is a wheel which is rotatably mounted on a bracket  54 . In operation, surface follower  56  tracks surface S and moves front debris shield  50  upwardly or downwardly depending on the level of the surface S. Front debris shield  50  also includes a skid plate  58  which enables the front debris shield to ride along an uneven surface S. Front debris shield  50  includes a chain  66   a  attached thereto, having a plurality of links  67  which are sized to be removably received in one of a plurality of keyhole slots  48   a  in the upper section  42  of housing  28 . Chain  66   a  enables the front debris shield  50  to be positioned at different elevations to facilitate servicing. 
     The lower section  44  also includes an outside debris shield  70 . The outside debris shield  70  is slideably mounted to housing  28  in the same manner as the front debris shield  50 , by means of slots  72 , pins  74 , washers  76  and retainers  78 . Outside debris shield  70  also includes skid plate  80  and two chains  66   a ,  66   c  which also are removably received in keyhole slots  48   b ,  48   c  on the upper section  42  of housing  28 . An inside debris shield  71 , which includes a sidewall, is depicted in FIG.  4 . 
     As shown in FIGS. 1 and 2, the surface preparation apparatus includes a remote control and monitor system  24 , including cable  26  which enables one person to operate the apparatus from a prime mover or tow vehicle V. The system  24  includes a simple toggle switch control unit  24   a  which allows the user to actuate each of the three pairs of hydraulic cylinder  132  and  134 ,  202  and  204 , and  214  and  216  which allow the STU  22  to (1) pivot with respect to the tow bar  12  so as to be offset to the left or right with respect to the transverse axis TV; (2) raise or lower with respect to the surface S; or (3) tilt to the left or the right with respect to the longitudinal axis  240  of the wheels  186 . The monitoring unit  24   b  provides indications of the relative position of the STU  22  in regard to the extremes of these variations. 
     In a preferred embodiment, the hydraulic system is an open center, return line filter, solenoid operated system having in-cab pendent controls for raising and lowering the STU  22 ; swing the STU  22  to the left or right; or tilting the STU  22  to the left or right. Preferred indicators include an oil pressure gauge, and engine temperature gauge, and a tachometer; other controls include a master switch, a key start/stop, an electric throttle control, and an emergency stop palm switch. 
     As shown in FIG. 3, the surface treatment unit  22  is pivotally attached to and supported by tow bar  12  and support mechanism  150 . The second end  16  of tow bar  12  is bolted or otherwise affixed to a first end  102  of a first beam frame  100 . The first beam frame  100  includes a first support surface  106  which slideably engages a flange  46  which is affixed to an upper beam  32  attached to the front side  30  of housing  28 . Shown in hidden lines, the first frame  100  extends partially into housing  28 . Also in hidden lines is an extension  108  with a first end  110  and a second end  112 , with the first end  110  is welded or otherwise affixed to the second end  104  of the first frame  100 . The extension  108  extends rearwardly from the first frame  100  and terminates at a second end  112  adjacent the rear side  36  of housing  28 . The second end  112  is pivotally engaged with a vertical pivot pin  120  which is fixedly retained within a generally vertical aperture (not shown) in extension  108  and which extends upwardly and downwardly from the second end  112  of the extension  108 . The vertical pivot  120  engages an upper beam  38  and a lower beam  40  which are attached to and extend horizontally along the rear side  36  of housing  28 . 
     Attached to, and extending rearwardly from housing  28 , is the support mechanism  150 . The support mechanism  150  includes a second frame  152  attached to housing  28 , and a lift unit  188  which is adjustably connected to the second frame  152  and pivotally connected to a third frame  180 . The lift unit or mechanism  188  includes column  192  which is pivotally secured to the second frame  180 , and third and fourth actuators  202 ,  204 , in electrical communication with the control unit  24   a , which are adjustably attached between brackets  164  and  200  to enable first and second columns  158 ,  192  to telescope relative to each other, thus raising or lowering surface treatment unit  22  as the third and fourth actuators  202 ,  204  are extended or retracted. Although two actuators are depicted in the illustrations of the preferred embodiment, the particular number of actuators used can vary without departing from the spirit and scope of the invention. Brackets  200  are secured, preferably welded, to a U-shaped pivot frame  201  which includes sleeve  190  which rotatably encircles horizontal pivot pin  182  which pivotally joins the U-shaped pivot frame  201  to the third frame  180 . The third frame  180  is secured to axle  184 , to which wheels  186  are rotatably attached. The first end  154  of the second frame  152  is attached to housing  28  at the rear side  36 . A bumper or push bar  178  is attached to a second end  156  of the second frame  152 . The first column  158  has upper and lower ends  160 ,  162 . The first column is attached to the second frame  152  proximate the lower end  162  such that the upper end  160  lies above the horizontal plane of the second frame  152 . The first column  158  slidingly receives the second column  192  of lift unit  188 . About midway along the length of the first column  158  and attached thereto, are brackets  164 , 200  onto which the hydraulic cylinders  202 ,  204  of the lift mechanism  188  are adjustably connected. 
     The third frame  180  includes additional elements of the lift unit  188 . The third frame  180  includes an axle  184  having a longitudinal axis  240  which rotatably supports wheels  186  in a conventional manner. The third frame  180  also includes a horizontal pivot  182  (FIG. 6) having a longitudinal axis (not shown) which is perpendicular to the longitudinal axis  240  of the axle  184 . The horizontal pivot  182  rotatably carries a sleeve or collar  190  (FIG. 6) within the U-shaped pivot frame  201 , to which a lower end  194  of the second column  192  is attached. Second column  192  is sized to be slideably received by first column  158  in a nesting or telescoping arrangement. A pair of brackets  200 , attached to a pair of U-shaped brackets  210 ,  212  which are integrally joined to the sleeve or collar  190  to form the U-shaped pivot frame  201 , (see FIG. 6) onto which components of the lift unit are connected. 
     The front side of the surface treatment unit  22 , depicted in FIG. 4, shows the arrangement of an offset or shift mechanism consisting primarily of hydraulic cylinders  132 , 134  which cause the STU  22  to pivot with respect to tow bar  12 . The cylinders  132 ,  134  are connected between housing  28  and first frame  100  which is fixed to the tow bar  12 . The front side  30  of housing  28  includes and upper beam  32  and a lower beam  34 . The upper and lower beams include apertures which engage support mounting pins  136 . The first frame  100  includes a pair of brackets  140  located on either side thereof which include apertures which engage mounting pins  137 . First and second hydraulic cylinders  132 ,  134  are attached to the mounting pins  136 ,  137  so that they are positioned adjacent the housing  28  and the first frame. The cylinders  132 ,  134  enable the surface treatment unit  22  and the support mechanism  150  to rotate about the vertical pivot  120  with respect to first frame  100  and tow bar  12 . Although two cylinders are depicted, the particular number of cylinders, or other linear actuators used in alternate embodiments can vary without departing from the spirit and scope of the present invention. 
     Although the preferred embodiments of the present invention have a cutter drum  82  off-set to the left or right of the transverse axis TV of the housing  28 , and the tow bar  12  is preferably interconnected with the housing  28  at a pivot point well behind the rotational axis  230  of the cutter drum  82  with respect to movement of the STU  22  in a forward direction when being drawn by the prime mover V, alternate embodiments of the present invention include STUs (not shown) wherein the cutter drum is not off-set to either side of such a transverse axis, and/or the main pivot point interconnecting the tow bar to the housing is either forward of, or immediately above the rotational axis  230  of the cutter drum. 
     Another view of the surface treatment unit  22  is shown in FIG.  5 . FIG. 5 is a left side elevation in which the cutter teeth  84  of the cutter drum  82  can be seen. The cutter teeth  84  are standard teeth available in the industry. Preferred teeth are standard weld-on blocks with knock-in/knock-out bits or optional quick change bolts in holder blocks. Although specialty drums as are known in the art within the scope of the present invention a preferred drum is arranged with teeth in a standard “staggered CHEVRON” pattern for maximum breakout force and horse power requirements. 
     The support  150  and the rear side  36  of surface treatment unit  22  illustrated in FIG.  6 . The tilt mechanism is actuated by a pair of cylinders  214 ,  216 , secured between a pair of U-shaped brackets  210 ,  212  which are attached to the collar  190  of the lift unit  188 . The cylinders  214 ,  216  which are adjustably connected between the brackets  210 ,  212  and the third frame  180 . The first U-shaped bracket  210  and a second U-shaped bracket  212  are attached to the collar or sleeve  190  so that they are transverse to the horizontal pivot  182  and the arms extend upwardly from a plane (not shown) passing through the pivot  182  proximate the third frame  180 . The brackets  210 ,  212  are secured to the second column  192  which moves up and down freely within the first column  158  which is secured to the second frame  152 . The upper ends of the first and second brackets are adapted to be connected to upper ends of the fifth and sixth cylinders  214 ,  216 . When the cylinder  214 ,  216  are alternately extended or contracted, the third frame  180  rotates about the horizontal pivot  182  relative to the surface treatment unit  22 , the U-shaped pivot frame  201  and the lift unit  188 . As the lift unit  188  raises and lowers the surface treatment unit  22 , the U-shaped brackets will move up and down freely with respect to the second frame  152 . Although two cylinders are depicted, the particular number and type of linear actuators used can vary without departing from the spirit and scope of the invention. Moreover, although U-shaped brackets are depicted, other bracket configurations are also possible. 
     FIGS. 7A and 7B depict the lift unit  188  as the third and fourth cylinders  202 ,  204  are extended in  7 A and withdrawn in  7 B. In  7 A, the surface treatment unit  22  is raised and supported by support wheels  186  and a prime mover or tow vehicle (not shown). In  7 B, the surface treatment unit  22  lowered so as to be is adjacent to or resting upon a surface to be modified. 
     FIGS. 8A,  8 B, and  8 C depict the tilt mechanism of the surface treatment unit  22  in various stages of tilt with respect to support wheels  186 . In FIG. 8A the tilt mechanism is in a neutral orientation, where the rotational axis  230  of the cutter drum  82  is parallel to the longitudinal axis of the axle  240 . In FIG. 8B, the surface treatment unit  22  is tilted to the left with respect to the third frame  180 , where the rotational axis  230  of the cutter drum  82  is at an angle  250  relative to the longitudinal axis of axle  240 . In FIG. 8C, the surface treatment unit  22  is tilted to the right with respect to the third frame  180 , where the rotational axis  230  of the cutter drum  82  is at an angle  250   b  relative to the longitudinal axis  240  of axle  184 . 
     FIG. 9 shows the cutter drum  82  in relation to the support wheels  186  as the cutter drum  82  removes a uniform layer from a surfaces to be treated. Note that the tilt mechanism enables the cutter drum  82  to compensate and make the uniform cut in spite of the uneven surfaces upon which the wheels  186  pass over. 
     FIG. 10 shows the position of the cutter drum  82  as used to remove a shoulder of a surface S to create a smooth transition between two levels. Here, the rotational axis  230  of the cutter drum  82  and the longitudinal axis of the axle (not shown) may very well be parallel to each other. This demonstrates the flexibility of the present STU  22 , providing users with greater capabilities when preparing pavement and the like for subsequent resurfacing operations. 
     FIGS. 11A,  11 B, and  11 C depict the offset mechanism as it manipulates the surface treatment unit  22  to the center when following directly behind the tow vehicle, to the left side of the direction of travel T when the STU  22  is offset to the left and to the right side when the STU  22  is offset to the right. Shown in schematic form, the tow bar, first frame, and extension are depicted as a single integral unit which extends from the point of attachment to a prime mover or tow vehicle (not shown) to the vertical pivot  120  to which the surface treatment unit  22  (shown in dashed lines) is rotatably attached. It will be appreciated from these plan views, that the pivotal attachment of the tow bar  12  or the extension thereof is well behind the rotational axis  230  of the cutter drum  82  with respect to the direction of travel T. As can be seen, cutter drum  82  is offset toward the right end of the surface treatment unit  22 . 
     When first and second cylinders  132 ,  134  are extended and withdrawn, the surface treatment unit  22  is rotated about the vertical pivot  120 . Although two cylinders are depicted, the particular number and type of linear actuators used can vary without departing from the spirit and scope of the invention. 
     As mentioned above the standard engine used in the present STU  22  is a 180 horsepower Caterpillar® engine. Preferred embodiments of the STU  22  of the present invention have a 260 horsepower Caterpillar® diesel engine. The preferred cutter drum  82  is 40 inches wide along its rotational axis  230 . In the standard STU  22 , the ration of horsepower to feet of cutter drum surface is 54. In the preferred embodiment having a 260 hp engine that ratio is 78, and if the engine has as much as 275 horsepower, that ratio will be 82.5. 
     The ratio of horsepower to feet of cutter drum surface (HP ratio) is important because a higher HP ratio enables the STU  22  to cut through asphalt and other surfaces at a faster rate of speed. That means that the STU  22  can be pulled at a faster rate and the surface can be prepared, or “reclaimed” at a faster rate. In preferred embodiments of the present invention the STU  22  will have an HP ratio of at least about 45 (e.g. 40″ cutter drum and 150 hp engine); preferably at least about 48 (e.g. 40″ cutter drum and 160 hp engine); more preferably at least about 51 (e.g. 40″ cutter drum and 170 hp engine); even more preferably at least about 54; (e.g. 180 hp engine); even more preferably at least about 57; (e.g. 190 hp engine) even more preferably at least 60 (e.g. 200 hp engine); even more preferably at least about 63 (e.g. 210 hp (engine); even more preferably at least about 63 (e.g. 210 hp engine); even more preferably at least about 66 (e.g. 220 hp engine); even more preferably at least about 69 (e.g. 230 hp engine); even more preferably at least about 72 (e.g. 240 hp engine); even more preferably at least about 75 (e.g. 250 hp engine); even more preferably at least about 78 (e.g. 260 hp engine); even more preferably at least 82.5 (e.g. 275 hp engine). 
     It will be appreciated that the prior art devices are not directed toward speed of cutting, but rather to large areas. When using a device for smaller areas, speed may be an even bigger factor because the faster the one job can be completed, the faster the workers can get on to the next job and the less need there will be for conventional resurfacing units. The present apparatus will effective cut a path through an asphalt road surface when drawn at speeds of greater than about 0.5 miles per hour (mph), preferably about 0.75 mph, and more preferably about 1.0 mph. 
     The weight of the STU  22  is also a factor because the weight of the unit, the more consistent the cutting function will proceed. The preferred STU  22  will weigh approximately 8.5 tons, preferably 8.58 tons, and the ratio of weight to feet of cutter drum surface (weight ratio will be at least about 5000, preferably at least about 5100, more preferably at least about 5150. 
     Alternate embodiments of the present STU will include a reservoir to store rejuvenating fluids which can be mixed with asphalt as the asphalt is reclaimed or pulverized. Such fluids are well known in the art and include polymer asphalt emulsions such as those sold by Koch Petroleum. These fluids prepared the pulverized asphalt for rolling which will complete the resurfacing process. 
     The most preferred STU  22  has a 260 horsepower Caterpillar® diesel engine. The unit also is equipped with quick change holder blocks for the bits. When towed with a pick up truck, the depth of cut is somewhat more limited, as compared to towing with a tractor, road grader, dump truck or the like. The maximum cut depth is generally about 12″ deep. 
     The overall cost of operation of any reclaiming machine should include the cost of transporting, travel permits, maneuverability, operator skill level and other considerations. When these costs are considered, the use of the present invention is exceptionally cost efficient, not only from an original price basis but simply on a day to day operating basis as well. 
     Typical road vehicles employed in the United States, and perhaps elsewhere, have a width of generally about 8′4″ to about 8′6″. Machinery and other trailer type devices which are towed behind such vehicles generally conform to the same widths so that these trailer-type devices can easily seen by the operators of the vehicles using their outside mirrors during any towing activities. However, these vehicles and the trailer-type devices they generally tow are not easily shipped overseas in multiple mode shipping containers of the type now in common use in commercial trade both regionally and internationally. One key problem is the these vehicles, and the trailer-type devices the often pull, are generally to wide to fit into these containers because the containers have an inside width of only 7′4″. Therefore, large equipment which must be shipped cannot be shipped in these multiple mode containers if they are too wide to fit in the containers. 
     In preferred embodiments of the present invention, the housing  28  of the STU  22  is less than about 7′4″ wide, in order to fit easily into a standard shipping container used for “container shipping” which has a standard inside width of 7′4″. Preferably, the width of the housing will be about 7′3″ or less, preferably about 7′2″ or less. In alternate embodiments (not shown) the tow bar may be shipped in a number of pieces, unassembled, so that the entire SPA can be enclosed in a single multiple mode shipping container of the type known in the art for shipping overseas on container carrying ocean going vessels. 
     In FIGS. 12 and 13, an alternate surface preparation apparatus  10 ′ is illustrated which includes a tow bar  12 ′ having two horizontally pivotally connected end portions  12   a ′ and  12   b ′ and a wheeled support assembly  21 ′ having a pair of heavy duty caster wheels  21   a ′. The support assembly  21 ′ is secured to the first end portion  21   b ′ of the tow bar  12 ′ with a pair of u-bolts  23 ′. The support assembly  21 ′ may be provided when the weight of the STU  22 ′ is too great for the prime mover V′ to support. The horizontal pivot  25 ′ of the tow bar  12 ′ allows the weight of the STU  22 ′ to rest entirely upon the wheels  21   a ′ of the assembly  21 ′. It will be appreciated that the u-bolts  23 ′ may loosened, and the support assembly may be slideably moved along the length of the first portion  12   a ′ of the tow bar  12 ′ to reduce the length of separation between the wheels  21   a ′ of the support assembly  21 ′ and the wheels  186 ′ of the STU  22 ′, thereby lowering the leverage placed upon the caster wheels  21   a ′ by the weight of the STU  22 ′. 
     It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of present invention, the sequence or order of the specific steps, or the actual compositions or materials used may vary somewhat. Further more, it will be appreciated that this disclosure is illustrative only and that changes may be made in detail, especially in matters of shape, size, arrangement of parts or sequence or elements of aspects of the invention within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

Summary:
A compact, easily transportable, surface preparation apparatus which includes a surface treatment unit having a cutter drum powered by its own power source. The apparatus includes transport/support wheels and a tow bar preferably interconnected at each end, of the surface treatment unit the rearward connection being a pivotal connection. The surface treatment unit has a longitudinal axis and a transverse axis, with the longitudinal axis perpendicular to the towing direction and the transverse axis coincident with the towing direction. The cutter drum has a rotational axis and is contained within the surface treatment unit and arranged such that the rotational axis is parallel to the longitudinal axis of the surface treatment unit. The cutter drum is off-set relative to the transverse axis of the surface treatment unit such that the cutter drum operates at one end of the surface treatment unit. The surface treatment unit is pivotally attached to the tow bar to enable the surface modifier to operate adjacent edges of a surface to be treated e.g., the shoulder of a road surface. The height and sideways tilt of the surface treatment unit may be adjusted as desired to produce surface profiles of different configurations.