Disclosed is a cleaning system for removing coatings from a hard surface by high pressure liquid. The system employs a combination liquid and vacuum reservoir connected to a high pressure pump for directing ultra high pressure water through a blast head mounted on a front portion of the vehicle. The cleaning system is preferably mounted on a single truck with a single prime mover. The drive-line of the vehicle is constructed and arranged to operate in two distinct modes, e.g. a transport mode and a work mode. In the transport mode, a first transmission coupled to the rear portion of the prime mover delivers torque from the engine to the rear wheels of the vehicle. In the work mode, the prime mover is utilized to mechanically drive the bed mounted equipment as well as provide motive force in the form of mechanical-hydrostatic transmission to propel the system at a speed suitable for marking removal.

RELATED APPLICATIONS 
     This application is related to U.S. patent application Ser. No. 10/884,643, filed Jul. 2, 2004 and entitled “Stripe Removal System”, now U.S. Pat. No. 7,255,116; U.S. patent application Ser. No. 11/340,738, filed Jan. 26, 2009; U.S. patent application Ser. No. 11/368,020, filed Mar. 3, 2006; U.S. patent application Ser. No. 11/368,035, filed Mar. 3, 2006; U.S. patent application Ser. No. 11/835,642, filed Aug. 8, 2007; U.S. patent application Ser. No. 12/394,806, filed Feb. 27, 2008 and U.S. patent application Ser. No. 12/395,302, filed Feb. 27, 2009, the contents of which are incorporated herein in their entirety. 
     FIELD OF THE INVENTION 
     This invention relates to the field of high pressure water cleaning devices for highways, runways, parking decks, and other hard surfaces. 
     PRIOR ART BACKGROUND 
     The use of paint stripes on road surfaces is the accepted method to indicate vehicle lanes, crossing lanes, parking areas and numerous other indicators. Various pavement marking techniques are well known in the art, including the use of traffic paint, thermoplastics, epoxy paints and preformed tapes. Most pavement marking systems are intended to be as durable and permanent as possible, and resistant to weathering and wear from traffic. Common road surfaces are asphalt and concrete. The removal of such striping is typically required when the road is to be resurfaced or if the indication is to be changed. 
     When polymers such as paint or plastic are used for roadway marking, the surface of the pavement is penetrated from ⅛-⅜ inch, so that mere surface removal of the marking material is not sufficient to remove the marking. Therefore, current pavement marking removal machines often employ various forms of cutting devices to remove the marking material, as well as a portion of the underlying layer of pavement material in order to effectively remove painted lines. 
     Commonly known methods for removal of such markings typically include the use of abrasive grinding wheels, material removing cutters, or blasting of abrasive particles against the material to be removed. However, the use of these devices often results in undesirable grooves in the pavement surface. 
     For example, one type of cutting machine is disclosed in U.S. Pat. No. 5,236,278 known as a “Road Pro” manufactured by Dickson Industries, Inc. This type of machine employs parallel passive shafts that extend between circular rotating end plates. Hardened steel star wheels are carried on the parallel passive shafts, and these star wheels strike and abrade the pavement surface. While this type of device is effective for removal of markings, it often creates excessive heat which may melt thermoplastic materials causing equipment to gum up. 
     Another approach to pavement marking removal is the use of diamond saw blades or cutters arranged to make a dado cut. Still other types of machines use grinders or shot blast as described in U.S. Pat. Nos. 4,753,052; 4,376,358; 3,900,969; 4,336,671; 3,977,128 and 4,377,924. Unfortunately, these devices must remove a portion of the pavement material to effectively remove the marking, thereby leaving unsightly and potentially dangerous grooves in the pavement. 
     It is also known in the art to utilize high-pressure water jets to remove markings from pavement. The instant inventor teaches a Stripe Removal System in U.S. application Ser. No. 10/884,643, the contents of which are incorporated herein in their entirety. In addition, NLB Corporation markets a high pressure water jet system for removing paint from pavement under the name “STARJET”. BLASTERS Corporation markets a high pressure water device which is mounted on a truck similar to the STARJET device. 
     A common problem associated with these prior art devices relates to the requirement of multiple prime movers, e.g. internal combustion engines, for operation of the various systems necessary for effective stripe removal. For example, these devices utilize one engine for transport of the system, e.g. the truck engine. A second engine is required for operation of the high-pressure water pumps, which develop at least 25,000 PSI. In the devices equipped with a vacuum system, a third engine is required for operation of the vacuum pump. Internal combustion engines are generally heavy and therefore consume a substantial amount of the allowed overall weight of the vehicle. In addition, engines consume a large amount of the bed space available on the truck. System maintenance and fuel costs are also substantially increased with the requirement of multiple engines. Still yet, mounting multiple engines on a single vehicle frame causes problems with proper weight distribution among the truck's various axles. With the exception of the instant inventor's prior teachings, the prior art generally requires multiple vehicles or trailers to transport a suitable amount of equipment to complete a marking removal task. 
     Therefore, what is needed in the art is a stripe removal system that is capable of eliminating the weight and maintenance of auxiliary engines used for powering deck mounted equipment. The system should provide power suitable to transport the system to a desired job site at typical highway speeds. Once at the job site the single prime mover should be configured to disconnect from a portion of the vehicle drive-line and connect to deck mounted equipment for supplying power thereto. In addition, the system should provide power to the drive axle of the vehicle in the form of a mechanical-hydrostatic drive suitable for propelling the system along a surface at speeds suitable for marking removal. 
     SUMMARY OF THE PRESENT INVENTION 
     Briefly, disclosed is a cleaning system for removing coatings from a hard surface by high pressure liquid. The system employs a combination liquid and vacuum reservoir connected to a high pressure pump for directing ultra high pressure water through a blast head mounted on a front portion of the vehicle. The cleaning system is preferably mounted on a single truck with a single prime mover. The drive-line of the vehicle is constructed and arranged to operate in two distinct modes, e.g. a transport mode and a work mode. In the transport mode, a first transmission coupled to the rear portion of the prime mover delivers torque from the engine to the rear wheels of the vehicle. In the work mode, the prime mover is utilized to mechanically drive the bed mounted equipment as well as provide motive force in the form of mechanical-hydrostatic transmission to propel the system at a speed suitable for marking removal. The second transmission is constructed and arranged to disconnect the first transmission from the rear drive gear, transferring the torque produced by the prime mover to the bed mounted equipment. Additionally in this configuration, the second transmission powers a variable volume hydraulic pump. Pressurized fluid produced by the hydraulic pump is used to provide power to a fixed or variable displacement hydraulic motor coupled through the second transmission to the rear axle drive gears. The hydrostatic drive is controlled by the operator from the cab of the truck to allow infinite speed control up to a predetermined limit for marking removal. 
     Therefore, it is an objective of this invention to provide a surface marking removal system constructed and arranged to operate with a single prime mover. 
     It is another objective of the instant invention to provide a surface marking removal system which operates in a first mode for transport of the system and a second mode for removal of surface markings, wherein power for both modes is supplied by a single prime mover. 
     It is a further objective of the instant invention to provide a surface marking removal system which includes a second transmission for selective control between the first and second modes, wherein the vehicle's prime mover supplies power for operation of bed mounted equipment from the vehicle's prime mover in the second mode. 
     It is a further objective of the instant invention to provide a surface marking removal system which operates a high pressure water jet, a vacuum recovery, and an infinitely variable speed hydrostatic drive from a single prime mover. 
     It is yet another objective of the instant invention to provide a surface marking removal system which permits higher than standard flow rates without the additional weight of a larger engine to power the high pressure water pump. 
     It is still another objective of the instant invention to provide a surface marking removal system which provides increased horsepower to a high pressure pump to permit high surface marking removal rates due to increased water flow capacity. 
     Still yet another objective of the instant invention is to provide a surface marking removal system in which the construction of the system permits the transport of additional water without increasing weight over prior art constructions for longer operation times at typical flow rates. 
     Other objectives and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention. The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       While the novel features of the invention are set forth with particularity in the appended claims, the invention, both as to organization and content, will be better understood and appreciated from the following detailed description, taken in conjunction with the drawings, in which: 
         FIG. 1  is a side view, partially in section, of one embodiment of the instant invention illustrated with the rotary spray head in the operating position; 
         FIG. 2  is a partial side view illustrating the prime mover and the drive line of one embodiment of the instant invention; 
         FIG. 3  is a top view of the embodiment shown in  FIG. 1 ; 
         FIG. 4  is a side view of one embodiment of the instant invention illustrated with the rotary cleaning head in the transport position; 
         FIG. 5  is a schematic illustration of the second transmission utilized in the instant invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The marking removal system  10 , shown in  FIG. 1 , includes a prime-mover truck  12  having an elongated frame  14 . Mounted on a front portion of the elongated frame  14  is a cab  16  for enclosing the operator as well as the driving and operating controls. Mounted on a front portion of the frame is a prime mover  44  ( FIG. 2 ). The prime mover is generally an internal combustion engine of a type well known in the art, utilizing diesel, gasoline, propane, natural gas or other suitable fuel. 
     Referring to  FIG. 2 , the prime mover  44  is connected to the truck drive-line which includes a first transmission  46  and a second transmission  48  as well as the drive axle gears  50 . The first transmission is operatively coupled to the prime mover as is well known in the art. The first transmission is preferably a manual type transmission with multiple forward and reverse gears such as is well known in the art. Alternatively, an automatic transmission having at least one forward and one reverse gear may be utilized without departing from the scope of the invention. The first transmission includes a case  52  and an output shaft  54 . 
     The second transmission  48  is secured to the frame of the truck between the output shaft  54  of the first transmission  46  and the drive axle  50 . The second transmission includes a case  56 , a first input shaft  58 , a first output shaft  60 , a second output shaft  62 , a third output shaft  64 , a hydraulic pump output  66 , and a hydraulic motor input  68 . In the preferred embodiment, the first input shaft  58  and the first output shaft  60  are axially aligned to extend from both sides of the case  56 . Also within the preferred embodiment, the second and third output shafts  62 ,  64  are axially aligned to extend from both sides of the case  56  and are spaced above the first input and output shafts as is illustrated in  FIG. 2 . Alternatively the second and third output shafts  62 ,  64  may be parallel with respect to one another and spaced in a horizontal plane to be above or below the first input and output shafts respectively. The hydraulic pump output  66  and hydraulic motor input  68  are preferably positioned along the outer surface of the case  56  between the axis of the second and third outputs and axis of the first input and output. However, it should be noted that other positions suitable for mounting the hydraulic pump and motor may be utilized without departing from the scope of the invention. Transmissions such as the second transmission described above are available from suppliers such as Omsi Transmission of Volciano Italy, and are disclosed in U.S. Pat. Nos. 5,826,460 and 6,393,944, the contents of which are incorporated herein by reference. 
     A first drive shaft  70  is connected to the output  54  of the first transmission  46  and the first input  58  of the second transmission  48 . A second drive shaft  72  is coupled between the output shaft  60  of the second transmission  48  and the drive axle  50  of the truck. 
     Referring to  FIGS. 1-4 , mounted on a rear portion  74  of the frame  14  is a holding tank  18 , including a water tank portion  20  and a vacuum recovery tank portion  22 . In one embodiment the rear portion  24  of the holding tank is pivotally mounted on the truck frame  14  and hydraulically powered to tilt in the vertical plane to permit dumping of the contents of the vacuum recovery tank. The recovery tank  22  is operably connected to a vacuum pump  26  by a suitably sized conduit  28 . The vacuum pump is preferably capable of drawing approximately 1100 CFM (cubic feet per minute) of air through the vacuum tank. Operably connected between the vacuum tank and the vacuum pump is a dust separator  30 . The dust separator is constructed and arranged to prevent airborne particles drawn through the vacuum tank from being drawn through the vacuum pump and discharged into the atmosphere. 
     Also mounted on the frame is a high-pressure water pump  32 . The high-pressure water pump is capable of supplying 2-15 GPM (gallons per minute) of water to at least one spray head  34  at 25,000-45,000 PSI (pounds per square inch). In a most preferred embodiment, the high-pressure water pump is constructed and arranged to deliver 6 GPM to each of two rotating spray heads at about 40,000 PSI. A high pressure hose or conduit is used to connect the water pump with the spray head(s). 
     An articulating arm  36  having a first end  35  is pivotally secured to a front portion  37  of the frame  14  and at least one spray head  34  is mounted to the distal end  40  thereof. The articulating arm is constructed and arranged to be infinitely positioned relative to the front portion of the truck via pneumatics, hydraulics, electric motors or suitable combinations thereof. The articulating arm is also movable in a vertical manner to provide a storage position and an operating position. A joystick or other suitable control device (not shown) is provided in the cab  16  of the truck to allow an operator to manipulate the articulating arm throughout an operator determinable path. A plurality of high pressure nozzles (not shown) are rotatably secured within the spray head along an elongated tubular member (not shown). Rotation of the elongated tubular member is controlled via a hydraulic motor  76 . The hydraulic motor  76  is connected to a hydraulic pump  78  and/or  80  via a high pressure hose  82  and controlled from the cab of the truck. The spray head is carried on a chassis  84  supported on casters  86 . A shroud  88  descends from the chassis and surrounds the high pressure nozzles. The spray head is connected to the high pressure fluid pump by high pressure hose  90 , and the shroud  88  is connected to the vacuum tank by a vacuum hose  92 . 
     In one embodiment a ramp  19  is hinged to the edge of the frame  14  just behind the cab  16  of the truck. The ramp can be lowered to provide a pathway for a self propelled tractor  93  ( FIG. 3 ). The tractor is equipped with an articulating arm  36  and a spray head  34  mounted on a front portion thereof. As shown in  FIG. 1 , the ramp  19  is illustrated in the stowed or traveling position for highway transport. When the ramp is unfolded it is approximately 9 feet in length to provide a pathway for loading the tractor. The tractor  93  is constructed and arranged to be stored and transported on the truck in a position transverse with respect to the longitudinal centerline of the truck. This orientation requires the tractor, the articulating arm, and the spray head to be less than 8 feet 6 inches in length. The high pressure hose (not shown) and the vacuum hose (not shown) for the tractor may be supported by a swinging boom (not shown) which is mounted on the frame  14  to provide freedom of movement for the tractor and to prevent tangling or running over of the hoses by the truck. A tractor configured for transport in a transverse position is shown and described in the instant inventors co-pending application Ser. No. 10/884,643, entitled “Stripe Removal System” as well as the application entitled “Transportable Holding Tank for Stripe Removal Systems” filed Jan. 6, 2006 the contents of which are incorporated herein in their entirety. 
     Referring to  FIG. 5 , a schematic representation of one embodiment of the second transmission  48  utilized in the instant invention is illustrated. The construction of the second transmission provides the marking removal truck with two modes of operation, a transport mode and a work mode. In the transport mode, the first input shaft  58  of the second transmission is operatively coupled to the output shaft  60 . The engagement between the shafts may be accomplished with splined shafts and a ring having internal splines or other suitable means for coupling shafts. In the preferred embodiment a fluid powered cylinder  96  is utilized to slide a ring to engage the two shafts. Other means such as cables or levers may be utilized in place of the fluid cylinder without departing from the scope of the invention. This construction allows power from the prime mover  44  and the first transmission  46  to drive through the second transmission to the drive axle  50  of the truck for transport of the entire system in a conventional manner. 
     In the work mode, the input shaft  58  of the second transmission is uncoupled from the output shaft  60  via the fluid cylinder moving the engagement ring as described above. The second and/or third output shafts  62 ,  64  are coupled to the input shaft  58  via clutches  98  or other suitable means of engagement. Engagement of the second and/or third output shaft preferably engages the hydraulic pump output  66  to drive a first hydraulic pump  80 , most preferably a variable volume pump. The second output shaft  62  is operably connected to the high pressure water pump  32  via belts and pulleys. Alternatively gears, chain drives or suitable combinations thereof may be utilized to connect the second output shaft to the high pressure water pump. In one embodiment, the third output shaft  64  is operably connected to a second hydraulic pump  78  ( FIG. 1 ). The second hydraulic pump is fluidly connected to a second hydraulic motor  102  operably secured to the input shaft of the vacuum pump  26 . In another embodiment, the third output shaft  64  is operably connected to the vacuum pump via belts and pulleys as illustrated in  FIG. 4 . Alternatively, gears, chain drives or suitable combinations thereof may be utilized to connect the third output shaft to the vacuum pump without departing from the scope of the invention. In this embodiment the second hydraulic pump and motor are eliminated. 
     In the work mode the first hydraulic pump  80  and motor  94  are utilized to form a mechanical-hydrostatic transmission, wherein fluid generated by the first pump is delivered to the first hydraulic motor. The hydraulic motor is coupled to the hydraulic motor output shaft of the second transmission by suitable means such as a slip ring with internal splines  104 , gears, clutches, chains or suitable combinations thereof. In the preferred embodiment a fluid powered cylinder  106  is utilized to slide the slip ring to engage the output shaft to the hydraulic motor. Other means such as cables or levers may be utilized in place of the fluid cylinder without departing from the scope of the invention. A joystick type control (not shown) is provided within the cab of the truck to allow an operator to infinitely control the speed of the truck within a predetermined range. In a most preferred embodiment the mechanical-hydrostatic transmission is constructed and arranged to propel the system from 0 to 10 MPH (miles per hour). 
     The configuration described above is especially useful for marking removal. The prime mover may be set at an optimum RPM for efficiency or power. The bed mounted equipment is then powered from the prime mover, eliminating the need for additional prime movers for their operation. The weight of the additional prime movers is eliminated, allowing the truck to carry additional water for extended operation without the need to refill the water tank  20 . The mechanical-hydrostatic transmission allows the speed of the truck to be controlled for optimum marking removal. For example, the truck speed may be increased between marks being removed, such as a dashed line, without changing the rotational speed of the prime mover. In addition, the increased horsepower provided by the prime mover allows for increased water pump size when compared to the prior art. The increased water pump size facilitates increased removal rates or the ability to operate two spray heads as illustrated herein. Both spray heads may be secured to the articulating arm, as illustrated in  FIG. 3  for the removal of two lines simultaneously. Alternatively, the tractor spray head may be operated simultaneously with the spray head(s) on the front of the truck for removal of markings on opposite sides of a roadway. In addition to removing markings, the system is useful for tasks such as removal of accumulated rubber from airport runways, cleaning parking lots, factory floors and the like. 
     A number of embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the invention is not to be limited by the specific illustrated embodiment but only by the scope of the appended claims.