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CLAIM OF PRIORITY 
       [0001]    This application is a continuation of U.S. application Ser. No. 11/695,782, filed Apr. 3, 2007, the entire disclosure of which is incorporated by reference herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates generally to an earth reduction vacuum system for removing soil to expose underground utilities (such as electrical and cable services, water and sewage services, etc.), and more particularly to a vacuum system with improved mobility. 
       BACKGROUND OF THE INVENTION 
       [0003]    With the increased use of underground utilities, it has become more critical to locate and verify the placement of buried utilities before performing digging or excavation work. If the location of a buried utility is unknown, the use of conventional digging and excavation methods such as shovels, post hole diggers, powered excavators, and backhoes can cut, break, or otherwise damage the lines during excavation. 
         [0004]    Devices have been previously developed to create holes in the ground to non-destructively expose underground utilities to view. One design uses high pressure air delivered through a tool to loosen soil and a vacuum system to vacuum away the dirt after it is loosened to form a hole. Another system uses high pressure water delivered by a tool to soften the soil and create a soil/water slurry mixture. The tool is connected with a vacuum system for vacuuming the slurry away from the utility and into a collection tank. The tank may then be emptied by opening a door on the tank. 
         [0005]    Prior art vacuum systems are typically very large and heavy, and therefore must be mounted onto the bed of a carrier vehicle such as a heavy duty truck or trailer. One disadvantage of such prior art vacuum systems is that the work space must be large enough to accommodate the size of the system and its carrier vehicle. When working in small areas or areas with access points too small for a large vehicle, it may be impossible to position both the vacuum system and the vehicle in close proximity to the work area. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention recognizes and addresses disadvantages of prior art constructions and methods, and it is an object of the present invention to provide a self-propelled mobile vacuum system comprising a vacuum source that provides suction for the removal of debris, a collection tank for storing debris collected by the vacuum source, and at least two rolling drive systems for maneuvering the vacuum system within a work space. A motor provides power to the vacuum source and the two rolling drive systems, and the system is sized appropriately to pass through a standard residential fence gate having a opening width of about 36 inches. 
         [0007]    In another embodiment, a self-propelled mobile vacuum system comprising a vacuum source that provides suction for the removal of debris, a collection tank for storing debris collected by the vacuum source, and at least two rolling drive systems for maneuvering the vacuum system within a work space. A motor provides power to the vacuum source and the two rolling drive systems, and the system has an overall width within the range of 24 to 48 inches, an overall length within the range of 5 to 10 feet, and an overall height within the range of 60 to 84 inches. 
         [0008]    In still another embodiment, a self-propelled mobile vacuum system comprises a collection tank with a first low-pressure intake port and a first high-pressure port defined though the collection tank&#39;s external wall. A vacuum source with a second low-pressure intake port is operatively connected to the first high-pressure outlet port and creates a low-pressure condition inside the collection tank relative to ambient air pressure. The system also includes an elongated suction implement detachably connected to the first low pressure intake port for channeling debris into the collection tank, at least two rolling drive systems for maneuvering the mobile vacuum system within a work space, a motor providing power to the vacuum source and rolling drive systems; and a remote control used by an operator to direct the motion of the rolling drive systems when maneuvering said mobile vacuum system within the work place. The mobile vacuum system has an overall width within the range of 24 to 48 inches, an overall length within the range of 5 to 10 feet, and an overall height within the range of 60 to 84 inches. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    A full and enabling disclosure of the present invention, including the best mode thereof directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which: 
           [0010]      FIG. 1  is a perspective view of a mobile vacuum system in accordance with the present invention; 
           [0011]      FIG. 2  is a side view of the mobile vacuum system of  FIG. 1 ; 
           [0012]      FIG. 3  is a perspective view of the mobile vacuum system of  FIG. 1 ; 
           [0013]      FIG. 4  is an a perspective view of a earth reduction tool for use with the mobile vacuum system of  FIG. 1 ; 
           [0014]      FIG. 5  is bottom perspective view of the earth reduction tool shown in  FIG. 4 ; 
           [0015]      FIG. 6  is a partial exploded perspective view of the earth reduction tool of  FIG. 5 ; 
           [0016]      FIG. 7  is partial perspective view of the earth reduction tool of  FIG. 4  in use digging a hole; 
           [0017]      FIG. 8  is a side plan view of the earth reduction tool of  FIG. 4 ; 
           [0018]      FIG. 9  is a top plan view of the earth reduction tool of  FIG. 4 ; 
           [0019]      FIG. 10  is a bottom plan view of the earth reduction tool of  FIG. 4 ; 
           [0020]      FIG. 11  is a side section view of the earth reduction tool of  FIG. 9  taken along lines  11 - 11 ; 
           [0021]      FIG. 12  is a perspective view of the earth reduction tool of  FIG. 4  in use with the mobile vacuum system of  FIG. 1 ; 
           [0022]      FIG. 13  is a schematic view of the hydraulic, electric, water, and vacuum systems of the mobile vacuum unit of  FIG. 1 ; and 
           [0023]      FIG. 14  is a perspective view of the mobile vacuum unit of  FIG. 1  in use. 
       
    
    
       [0024]    Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the invention. 
       DETAILED DESCRIPTION 
       [0025]    Reference will now be made in detail to presently preferred embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope and spirit thereof. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
         [0026]    Referring to  FIGS. 1 ,  2  and  3 , a mobile earth reduction system  10  generally includes a chassis  12  having a front end  14  and a rear end  16 , a collection tank  18  located proximate to chassis rear end  16 , a motor  20  located proximate to chassis front end  14 , and a water reservoir tank  22  located between the motor and the collection tank. In a preferred embodiment, chassis  12  includes two hydraulically-operated tank treads  24 A and  24 B ( FIGS. 1 and 3 ) which allow easy maneuverability and transportation of the mobile earth reduction system. It should be understood that wheels may be substituted for the tank treads, and the components of the drilling system may be either directly mounted to the chassis or indirectly mounted to the chassis through connections with other system components. Preferably, treads  24 A and  24 B are spaced apart at a distance within the range of about 24 to 48 inches or less to minimize the overall width of the mobile earth reduction system. Additionally, the digging system preferably has an overall length of less than approximately 10 feet and an overall height of less than approximately 84 inches. Most preferably, the mobile earth reduction system has a width of 36 inches, a length of 8 feet and a height of 72 inches so that the system will pass through a standard residential fence gate (not shown) without requiring an operator  5  ( FIGS. 12 and 14 ) to remove sections of the fencing. 
         [0027]    Motor  20  is mounted to a frame  26  attached to chassis front end  14  and has an output shaft (not shown) that drives a hydraulic pump  30  as shown in  FIG. 13 . The motor output shaft is also connected to a water pump  32  ( FIG. 2 ) and a vacuum pump  34  by a series of vee-belts (not shown). It should be understood that alternative power transmission systems, such as chains or gear drives, may be substituted for the vee-belts to connect the motor output shaft to the water and vacuum pumps. Motor  20  is preferably a gas or diesel engine, although it should be understood that an electric motor or other motive means could also be used. In one preferred embodiment, motor  20  is a twenty-four horsepower gasoline engine, such as Model No. GX670 manufactured by the Honda Power Equipment division of the American Honda Motor Company. A muffler  36  is attached to the exhaust header (not shown) of the motor to reduce the motor&#39;s exhaust noise. Frame  26  supports vacuum pump  34 , a storage bin  38 , and two rigging shackles  40 A and  40 B ( FIG. 3 ) that provide connection points for lifting or tie-down rigging used to secure the digging system during transportation on a trailer or in the bed of a truck. 
         [0028]    A battery box  42  ( FIGS. 2 and 3 ) mounted to frame  26  beneath motor  20  houses a battery (not shown) that provides electrical power for the motor, control switches and any auxiliary equipment requiring electricity. A tool box  44  attached to chassis  12  on one side of the water reservoir houses digging and cutting implements and other tools. 
         [0029]    Referring now to  FIGS. 2 and 3 , a fuel tank  46  located aft of water reservoir tank  22  directly beneath collection tank  18 , supplies fuel to motor  20  through a fuel line (not shown). A control box  50 , located aft of motor  20 , houses a number of switches  52  ( FIG. 3 ) that control onboard functions such as overriding the collection tank float sensor and activating water pump  32  ( FIG. 2 ) as described in further detail below. 
         [0030]    Referring back to  FIGS. 1-3 , collection tank  18  is secured to chassis  12  by a first mounting bracket  60  positioned at chassis rear end  16  and a second mounting bracket  62  positioned proximate to water reservoir tank  22 . First bracket  60  is shorter than second bracket  62  and has a first brace  61 A equipped with a rigging shackle  63 A ( FIGS. 1 and 2 ) and a second brace  61 B equipped with a rigging shackle  63 B ( FIG. 3 ). Because of the relative height of first mounting bracket  60  and second mounting bracket  62 , the two mounting brackets position tank  18  at an angle of about 45 degrees with respect to chassis  12 . 
         [0031]    Referring to  FIGS. 1 and 2 , collection tank  18  has a discharge door  64  pivotally attached to the tank by a hinge  66  that rotates the door into and away from engagement with a sealing flange  70  on collection tank  18 . Discharge door  64  has a locking mechanism (not shown) operated by a locking handle  68 . When the door is closed against sealing flange  70 , the operator may rotate locking handle  68 , which engages the locking mechanism and seals the door against tank sealing flange  70 . The discharge door also has a gate valve  72  that allows the operator to drain water or other fluids from collection tank  18  without having to unseal and open door  64 . 
         [0032]    Referring to  FIG. 13 , water reservoir tank  22  connects to water pump  32 , which includes a low pressure inlet  80  and a high pressure outlet  82 . In the illustrated embodiment, water pump  32  can be any of a variety of suitable pumps that delivers between 500 and 3,000 lbs/in 2  at a flow rate of approximately two to four gallons per minute. In one preferred embodiment, water pump  32  is a Model No. TX1512 pump manufactured by General Pump of Mendota Heights, Minn. equipped with a clutch (not shown), preferably a model 10078 clutch also manufactured by General Pump. Water tank  22  is preferably formed from polypropylene and has an outlet  84  that connects to a strainer  86  through a valve  88 . The output of strainer  86  connects to the low pressure side of water pump  32  via a hose  90 . A check valve  92  is placed inline intermediate strainer  86  and low pressure inlet  80 . High pressure outlet  82  connects to a filter  94  and then to a pressure relief and bypass valve  96 . 
         [0033]    In a preferred embodiment, a “T”  98  and a valve  100 , located intermediate valve  96  and filter  94 , connect the pump high pressure output  82  to a plurality of clean out nozzles  102  mounted in collection tank  18  to clean the tank&#39;s interior, but it should be understood that the mobile vacuum system will function properly if the clean out nozzle apparatus is omitted. A return line  104  connects a low pressure port  106  of valve  96  to water tank  22 . Thus, when a predetermined water pressure is exceeded in valve  96 , water is diverted through low pressure port  106  and line  104  to tank  22 . A hose  108 , stored on a hose reel (not shown), connects an output port  110  of valve  96  to a valve  112  on a digging tool  114  ( FIG. 4 ). A valve control  116  ( FIG. 4 ) at a handle  118  of digging tool  114  provides the operator with a means to selectively actuate valve  112  on digging tool  114 . The valve delivers a high pressure stream of water through a conduit  120  attached to an exterior of an elongated pipe  122  that extends the length of digging tool  114 . 
         [0034]    Referring to  FIG. 4 , digging tool  114  includes handle  118  for operator  5  ( FIG. 12 ) to grasp during use of the tool, a head  124 , and an elongated pipe  122  that connects handle  118  to head  124 . A connector  126 , such as a “banjo” type connector located proximate to handle  118 , connects the vacuum system on mobile earth reduction system  10  ( FIG. 1 ) to a central vacuum passage  128  ( FIG. 5 ) in digging tool  114 . It should be understood that other types of connectors may be used in place of “banjo” connector  126 , for example clamps, clips, or threaded ends on hose  130  and handle  118 . Referring to  FIGS. 8 and 11 , vacuum passage  128  extends the length of elongated pipe  122  and connects at an end (not shown) to one end of a vacuum hose  130  ( FIG. 12 ). The other end of hose  130  connects to an inlet port  200  ( FIG. 3 ) on collection tank  18 . Referring to  FIG. 6 , a second end  128   a  of vacuum passage  128  is located proximate to an end  158  of digging tool head  124 . 
         [0035]    Referring to  FIGS. 5 and 6 , a fluid manifold  136 , located at one end  138  of head  124 , connects a water conduit  120  to a water feed line  140  formed through head  124 . In one embodiment, water feed line  140  is integrally formed in the head during casting of the head. However, it should be understood that the water feed line may also be added to the head after the head is cast. Head  124  contains two sets of a plurality of nozzles  142  and  144 , the first set  142  being angled radially inwardly at approximately 45 degrees from a vertical axis of the digging tool, and the second set  144  being directed parallel to the axis of the digging tool. It should be understood that the angle of first set  142  may be adjusted depending on the application of the digging tool to almost any angle between 0 and 90 degrees to enhance the digging effect of the tool. 
         [0036]    Each nozzle is set in a countersunk hole  146  formed in a bottom surface  148  of head  124  such that the end of each nozzle is recessed from bottom surface  148 . During the manufacture of a head that includes an integrally cast feed line  140 , a plurality of tap holes  150  ( FIG. 6 ) may be drilled into bottom surface  148  so that the holes tap into water feed line  140 . Next, each countersunk hole  146  may be concentrically formed with each tap hole  150 . Preferably, tap holes  150  have screw threads so that the nozzles may be threadedly attached to the tap holes and communicate with the water feed line. 
         [0037]    During use of drilling tool  114 , nozzles  142  and  144  produce a spiral cutting action that breaks the soil up sufficiently to minimize clogging of large chunks of soil within vacuum passage  128  and/or vacuum hose  130 . Vertically downward pointing nozzles  144  enhance the cutting action of the drilling tool by allowing for soil to be removed not only above a buried utility, but in certain cases from around the entire periphery of the utility. In other words, the soil is removed above the utility, from around the sides of the utility, and from beneath the utility. This can be useful for further verifying the precise utility needing service and, if necessary, making repairs to or tying into the utility. 
         [0038]    Still referring to  FIGS. 5 and 6 , an air feed passage  152  is formed in head  124  and has a first opening  154  at head end  138  and a second opening  156  at head second end  158 . In one preferred embodiment, air feed passage  152  is integrally formed in the head when it is cast. However, it should be understood that the air feed may also be formed from tubing extending between head ends  138  and  158 . In one preferred embodiment, second opening  156  is located at or tangential to bottom surface  148  and may be formed as a single opening or as multiple openings. 
         [0039]    In some embodiments, head  124  may be integrally formed with elongated pipe  122 , and air feed passage first opening  154  may be located anywhere along the length of the elongated pipe, provided the air feed passage first opening is located at a position distal from head second end  158 . Thus, it should be understood that head  124 , whether separate from or integral with elongated pipe  122 , is considered to be a part of the elongated pipe. For purposes of this discussion, distal from the head second end may refer to a position anywhere from several inches away from the head second end to a point proximate the elongated body first end. What should be understood by those of skill in the art is that air intake opening  154  should not be located at any point along head  124  or elongated pipe  122  that would be covered by the material to be removed by the digging tool. It should also be understood in that some embodiments, digging tool  114  may not come equipped with a water feed system. 
         [0040]    Referring to  FIG. 12 , digging tool  114  may also include a control  160  for controlling the tool&#39;s vacuum feature. Control  160  may be an electrical switch, a vacuum or pneumatic switch, a wireless switch, or any other suitable control to adjust the vacuum action by allowing the vacuum to be shut off or otherwise modulated. An antifreeze system (not shown) may be provided to prevent freezing of the water pump and the water system. Thus, when the pump is to be left unused in cold weather, water pump  32  ( FIGS. 2 and 20 ) may draw antifreeze from the antifreeze reservoir (not shown) through the components of the water system to prevent water in the hoses from freezing and damaging the system. 
         [0041]    Referring again to  FIGS. 1 ,  2 ,  3  and  13 , vacuum pump  34  is preferably a positive displacement type vacuum pump. In one preferred embodiment, vacuum pump  34  is a Model 49URAI-DSL blower manufactured by Roots Blower Division of Dresser Roots, of Texas. Vacuum pump  34  has a low pressure intake port  170  and a high pressure outlet port  172  fitted with a silencer  174  that reduces the noise associated with the air forced out of the vacuum pump outlet port. Silencer  174  may be a Model TS30TR Cowl silencer manufactured by Phillips and Temro Industries of Canada. Vacuum pump intake port  170  is fitted with a vacuum relief device  176 , which may be any suitable vacuum valve, such as a Model 215V-H01AQE spring loaded valve manufactured by Kunkle Valve Division, Black Mountain, N.C. Vacuum relief device  176  controls the maximum negative pressure of the vacuum pulled by pump  34 , which is in the range of between 10 and 15 inches of Mercury (Hg) in the illustrated embodiment. 
         [0042]    Referring to  FIG. 1 , a blower pipe  178  connects vacuum relief device  176  with an air filter  180 , located upstream of pressure relief device  176 , that filters the vacuum air stream before it passes through vacuum pump  34 . In one preferred embodiment, the filter media may be a paper filter such as a FleetGuard filter manufactured by Cummings Filtration. Air filter  180  has an outlet port  182  that receives blower pipe  178  and an intake port  184  that receives a separator pipe  186 . The separator pipe connects air filter intake port  184  with an upstream outlet port  188  of a cyclonic separator  190 . The cyclonic separator has a hopper  192  and an inlet port  194  that receives an exhaust pipe  196  that connects with an exhaust port  198  on collection tank  18 . 
         [0043]    The vacuum air stream pulled through vacuum pump  34  produces a vacuum in collection tank  18  that draws a vacuum air stream through a collection tank inlet port  200 . When inlet port  200  is not closed off by a plug  202  ( FIGS. 1 and 3 ), the inlet may be connected to hose  130  leading to digging tool  114  ( FIG. 12 ). Thus, the vacuum air stream at inlet  200  is ultimately pulled through the tool&#39;s vacuum passage. Because it is undesirable to draw dirt or other particulate matter through the vacuum pump, a baffle system, for example as described in U.S. Pat. No. 6,470,605 (the entire disclosure which is incorporated herein), may be provided within collection tank  18  to separate the slurry mixture from the vacuum air stream. Dirt, rocks, and other debris in the air flow hit a baffle (not shown) and fall to the bottom portion of the collection tank. The vacuum air stream, after contacting the baffle, continues upwardly and exits through outlet  198 , entering cyclone separator  190 . The vacuum air stream then continues through filter  180 , blower pipe  178  and on to vacuum pump  34 . 
         [0044]    Referring again to  FIGS. 1 and 2 , collection tank  18  includes a discharge door  64  connected to the main tank body by hinge  66  that allows the door to swing open, thereby providing access to the tank&#39;s interior for cleaning Gate valve  72  may be opened to allow the liquid portion of the slurry in tank  18  to drain out without requiring the door to be opened. Gate valve  72  may also be used to introduce air into collection tank  18  to reduce the vacuum in the tank so that the door may be opened. 
         [0045]    Referring again to  FIG. 13 , a preferred embodiment of the mobile vacuum unit includes clean out nozzles  102  ( FIG. 13 ) positioned along the interior of collection tank  18 . Nozzles  102  are attached to a nozzle pipe  103  that communicates with water tank  22  when valve  100  is opened and delivers high pressure water from pump  32  to nozzles  102  for producing a vigorous cleaning action in the tank. When the nozzles are not being used for cleaning, a small amount of water may be allowed to continuously drip through the nozzles to pressurize them so as to prevent dirt and slurry from entering and clogging the nozzles. 
         [0046]    Nozzle pipe  103 , apart from being a conduit for delivering water, is also a structural member that includes a threaded male portion (not shown) on an end thereof adjacent discharge door  64 . When discharge door  64  is shut, screw-down type handle  68  mounted in the door is turned causing a threaded female portion (not shown) on pie  103  to mate with the male portion. This configuration causes the door to be pulled tightly against collection tank sealing flange  70  ( FIGS. 1 and 2 ). Actuation of vacuum pump  34  further assists the sealing of the door against the tank opening. 
         [0047]    In a preferred embodiment, operation of motor  20  provides power to a hydraulic drive system  400  through an input shaft (not shown) of hydraulic pump  30 . It should be understood that the motor output shaft (not shown) and the pump input shaft may be connected by any suitable alternative power transmission mechanism, such as a vee-belt, a chain, or a gear set. In one preferred embodiment, hydraulic pump  30  is a model 26004-RZC gear pump manufactured by the Eaton Hydraulics division of Eaton Fluid Power Group of Cleveland, Ohio. Pump  30  pressurizes hydraulic oil that energizes a first and a second hydraulic motor  416  and  418  as described in further detail below. Pump  30  has a low pressure inlet port  420  connected by a suction line  422  to a hydraulic oil reservoir  424  that holds between 15 and 20 gallons of hydraulic oil. Pump  30  also has a high pressure outlet port  426  that is connected by a supply line  428  to the inlet port (not shown) of a hydraulic manifold  430 . Hydraulic manifold  430  also has an exhaust port (not shown) connected to reservoir  424  by a return line  432 . Preferably, manifold  430  has three solenoid valves (not shown) that selectively direct the flow of pressurized hydraulic oil through motor supply lines  434 A,  434 B,  434 C, and  434 D to hydraulic motors  416  and  418  in response to the operator&#39;s manipulation of a remote controller  436  ( FIG. 14 ). 
         [0048]    Referring to  FIG. 14 , operator  5  may maneuver mobile earth reduction system  10  into a work space by operating a remote controller  436 . Controller  436  has an operator interface  438  that controls the movements of mobile earth reduction system  10 . In one preferred embodiment, remote controller  436  is a radio frequency transmitter model T60RX-08ASL manufactured by Cervis, Inc. of Harmony, Pa. As operator  5  directs the movement of mobile earth reduction system  10  by switches and buttons on remote controller  436 , the controller transmits radio frequency signals to a receiver  440 , preferably a model T60RX-08STL also manufactured by Cervis, Inc. Receiver  440  sends control signals to the solenoid valves in manifold  430  ( FIG. 13 ), and the opening and closing of the solenoid valves directs pressurized hydraulic oil in the appropriate direction and flow rates to hydraulic motors  416  and  418  ( FIG. 13 ). Accordingly, the hydraulic motors activate to move tank treads  24 A and  24 B together or independently in the forward or reverse directions. It should be understood that a pigtail controller that communicates with control box  50  could be substituted for the radio frequency transmitter and receiver to direct the movement of the system&#39;s tank treads. 
         [0049]    Referring to  FIG. 4 , once the operator maneuvers the mobile earth reduction system into the proper position within the work space to perform the desired drilling operation, the operator connects vacuum hose  130  to digging tool handle  118  using banjo connector  126 . High pressure water hose  108  is also connected to valve  112  to provide water from supply tank  22  to the digging tool as shown in  FIG. 13 . As tool  114  is used to dig a hole, it is pressed downwardly into the ground. For larger diameter holes, digging tool  114  is moved in a generally circular manner as it is pressed downward thereby removing material from a large cross-section area. Water flows out of nozzles  142  and  144  creating a water and soil slurry formed that is then vacuumed by tool  114  through vacuum passage  128  ( FIGS. 5 and 6 ) and accumulated in collection tank  18  ( FIGS. 1 ,  2  and  3 ). Once the hole is completed and the utility exposed, the vacuum system can be shut down, and the operator may examine or repair the utility as needed. 
         [0050]    Referring to  FIGS. 1 and 13 , mobile earth reduction system  10  can be used to dig multiple holes before having to empty collection tank  18 . However, once collection tank  18  is full, it can be emptied at an appropriate dump site. In emptying collection tank  18  of a preferred embodiment of the mobile earth reduction system, motor  20  is idled to maintain a vacuum in the collection tank. This allows door handle  68  ( FIG. 1 ) to be turned so that the female threaded member (not shown) is no longer in threading engagement with the male member (not shown) on nozzle pipe  103  ( FIG. 13 ), while the vacuum pressure continuing to hold door  64  ( FIG. 1 ) closed. Once motor  20  is shut down, the vacuum pressure is released and ambient air enters the tank, thereby pressurizing the tank and allowing the door to be opened. The inclined attitude of tank  18  allows door  64  to easily swing open to a vertical position so the slurry simply runs out of the collection tank. 
         [0051]    It should be appreciated by those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope and spirit of the invention. It is intended that the present invention cover such modifications and variations as come within the scope and spirit of the appended claims and their equivalents.

Summary:
A self-propelled mobile vacuum system comprising a vacuum source that provides suction for the removal of debris, a collection tank for storing debris collected by said vacuum source suction, and at least two rolling drive systems for maneuvering the vacuum system within a work space. A motor provides power to the vacuum source and the two rolling drive systems, and the system has an overall width within the range of 24 to 48 inches, an overall length within the range of 5 to 10 feet, and an overall height within the range of 60 to 84 inches.