Abstract:
An apparatus performing multiple different cleaning operations for cleaning fabrics, floor coverings, and bare floor surfaces is disclosed. A device according to the present invention selectively utilizes soil transfer and solution extraction technology. In one embodiment, an apparatus is disclosed having a cleaning implement in selective wiping contact with a surface to be cleaned, a cleaning solution dispenser which selectively wets with a cleaning solution a portion of the cleaning implement or a portion of the surface or both, a first selectively controllable vacuum extractor tool which when operating removes some of the dispensed cleaning solution and soil from the cleaning implement, and a second selectively controllable vacuum extractor tool which when operating removes soil and some of the cleaning solution directly from the surface intended to be cleaned. A method of use of such an apparatus is also disclosed. Portable and vehicle-based devices may be utilized to practice the different methods of cleaning.

Description:
RELATED APPLICATION 
     This application is a continuation-in-part and claims the benefit of priority pursuant to 35 U.S.C. 120 of U.S. Ser. No. 10/081,374, filed Feb. 22, 2002, which entire application is hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to surface maintenance or conditioning machines, and more particularly to those machines employing one or more surface maintenance or conditioning appliances or tools to perform a floor cleaning task. 
     BACKGROUND OF THE INVENTION 
     In general, proper carpet maintenance involves regular vacuuming and periodic cleaning to remove soil by methods such as hot water extraction, shampooing, bonnet cleaning, foam cleaning, etc. Some of the soil is loosely found between carpet fibers while other soil is held upon the carpet fibers by some means such as electrostatic forces, van der Waals forces, or oil bonding. Still other soil is mechanically trapped by carpet fibers. Regular vacuuming is essential as it removes some of the loose soil that damages the fibers. Vacuuming maintains the surface appearance of a carpet and keeps the level of soil in the pile at an acceptable level. Vacuuming removes only particulate soil and some unbound or loosely bound surface dirt, however, therefore, other methods of cleaning are periodically required to improve the appearance of the carpet. Wet cleaning methods are required to remove oils, greases, bound dirt, and other forms of matter that cause soiling on carpet. These methods are often used by professional cleaners and trained personnel. 
     One type of surface maintenance machine for carpet cleaning is referred to as a bonnet cleaner. Bonnet cleaners employ an absorbent bonnet or pad (hereinafter referred to as the “pad”) attached to a rotary driver for rotating the pad about an axis generally perpendicular to the carpet surface. Most commonly a solution of cleaning liquid is sprayed directly onto the carpet and then the rotating pad is used to agitate the wetted carpet. This action transfers soil from the carpet onto the pad. Since the pad is commonly two-sided, the pad may be reversed once one side of the pad gets saturated or soiled to a selected level. The pad may be periodically replaced and later cleaned depending upon the application and wear characteristics of the pad. 
     The soil transfer process of the bonnet cleaners may be characterized as a “circular engagement process” since the pad rotates in a circular motion essentially in the plane of the carpet surface. The method employed by bonnet cleaners has the advantage of being fast drying if a relatively small amount of cleaning liquid is employed. However the process is fundamentally unstable since the rotating pad starts out clean and becomes less and less effective as a cleaning tool as it collects soil. Additional limitations of bonnet cleaners include transferring soil from soiled areas to relatively cleaner areas, leaving much of the cleaning fluid in the carpet, and having the potential to damage the carpet. With respect to the latter, some carpets, particular twisted ply variations, may be damaged by aggressive engagement with the rotating pad. Additionally, the bonnet cleaning process is a relatively labor intensive process since the pad requires frequent soil monitoring and frequent removal of soiled pads. 
     Yet another limitation of bonnet cleaners is the relatively uncontrolled use of cleaning liquid in the carpet cleaning process as some areas of the carpet may receive more cleaning liquid spray than other areas. Reliance on operator spraying of cleaning liquid to the carpet surface may result in over wetting of some areas and under wetting of other areas. 
     Another type of surface maintenance machine designed for carpet cleaning is referred to as a “hot water extractor” or an “extractor machine.” Extractor machines are commonly used for deep carpet cleaning. In general, an extractor is a transportable self-contained device which (i) sprays cleaning liquid directly onto the carpet to create a wetted carpet portion, (ii) agitates the wetted portion with a brush, and (iii) removes some of the cleaning liquid and soil in the carpet through a vacuum system. Generally, the extraction process applies a relatively large quantity of cleaning liquid on the carpet. While the vacuum system recovers a portion of the applied cleaning liquid, a significant portion is retained by the carpet. As a consequence, carpet drying times are substantially longer than in the bonnet cleaning process. 
     FIG. 4 illustrates functions of a conventional extractor machine  80 . In general, extractor  80  is a transportable self-contained device which (i) sprays cleaning liquid directly onto the carpet to create a wetted carpet portion, (ii) agitates the wetted portion with a brush, and (iii) removes some of the cleaning liquid and soil in the carpet through a vacuum system. Components of a conventional extractor machine  80  include a solution tank  82 , a pump  84  for conveying solution from tank  82 , and a spray nozzle  86  for spraying solution onto a floor surface  88 . A brush motor  90  powers a brush  92  which engages the floor surface  88 . Subsequently, as the machine is move in an operational direction, a pickup tool or “extractor”  94  engages the floor surface  88  to remove soiled solution from the surface  88 . A vacuum fan  96  and recovery tank  98  are provided to respectively remove and receive soiled solution from surface  88 . Additional features of an extractor machine are disclosed in U.S. Pat. No. 4,956,891, assigned to Tennant Company, and incorporated herein by reference. 
     Another type of surface maintenance machine intending for carpet cleaning has been developed by Tennant Company and is the subject of U.S. application Ser. No. 10/081,374, entitled “Apparatus and Method for Cleaning Fabrics, Floor Coverings, and Bare Floor Surfaces Utilizing a Soil Transfer Cleaning Medium”, incorporated by reference herein. This method does not spray the water directly onto the surface being cleaned at all. Instead, In accordance with that invention, a revolving cleaning medium, such as a cylindrical roll, is wetted and wiped against a surface intended to be cleaned. In general, this method of cleaning includes the steps of (i) wetting a revolving cleaning medium with a cleaning solution, (ii) removing at least some of the cleaning liquid from the revolving cleaning medium directly after wetting by way of a moisture extraction device, and (iii) wiping the surface with the revolving cleaning medium so as to transfer soil from the surface to the revolving cleaning medium and subsequently removing transferred soil from the revolving cleaning medium. 
     FIG. 5 illustrates a soil transfer roll carpet cleaning machine  102 , such as taught in U.S. application Ser. No. 10/081,374. Components of a soil transfer roll cleaning machine  102  include a solution tank  104 , a pump  106  for conveying solution from tank  104 , and a spray nozzle  108  for spraying solution onto cleaning medium—rolls  100 . Motors  110  drive rolls  100  which engage the floor surface  112 . Extractors  114  engage the rolls  100  to remove soiled solution from rolls  100 . A vacuum fan  116  and recovery tank  118  are provided to respectively remove and receive soiled solution  120  from rolls  100 . In a preferred operation, one portion of the cleaning medium  100  is wetted with cleaning liquid, while another portion is being extracted to remove soil and cleaning liquid therefrom, and while yet another portion is being wiped against the surface to transfer soil from the surface to the cleaning medium  100 . The process continues in a revolving or cyclical manner so that each portion of the cleaning medium  100  is sequentially wetted, extracted, and wiped against the surface 
     SUMMARY AND OBJECTS OF THE INVENTION 
     An object of the present invention is the provision of a dual mode carpet cleaning machine. Another object of one embodiment of the present invention is to significantly decrease the amount of cleaning solution applied to a carpet surface during at least one mode of operation. The benefits of reduced solution usage are 3-fold. First, reduced solution usage lowers the cost of operation since it requires less clean water and less cleaning chemical to clean a given area and it produces less waste water to be disposed of after cleaning. Second, reduced solution usage increases productivity since the cleaning equipment can be operated for longer periods of time without stopping to refill or empty the solution tanks. Third, reduced solution usage results in a significantly shorter dry time after the cleaning process has been completed and before the area can be reopened for use. 
     Yet another object of the present invention is the provision of a cleaning process and apparatus for cleaning a variety of surfaces, including but not limited to floor surfaces, stairways, walls, and upholstered furniture or other fabric surfaces. 
     In accordance with one embodiment of the present invention, a transportable device is utilized to perform at least two different cleaning process on a carpeted surface. The device may be a relatively portable machine having a cleaning liquid tank, a soiled solution recovery tank, a vacuum system, and cleaning head. The cleaning head may include a floor pickup tool and brushes or rolls and associated drive mechanism. Vacuum extractor tools may be used to engage the rolls or other surface to remove soil and at least some of the soiled cleaning liquid. Common parts such as motors and brushes may be utilized during the two different cleaning processes. 
     In accordance with one embodiment of the invention in a first mode of operation a carpet extraction process is performed. In the first mode of operation a cleaning solution is sprayed onto the surface and/or brushes and the brushes agitate the floor surface to transfer soil from the surface into a soiled cleaning solution. The soiled cleaning solution is subsequently removed from the surface via a vacuum extractor tool and transported into a soiled solution recovery tank. In a second mode of operation a soil transfer roll cleaning process is performed utilizing revolving soil transfer rolls having portions of each roll being successively wetted, extracted, and wiped against a surface intended to be cleaned. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective illustration of one embodiment of a cleaning machine according to the present invention. 
     FIG. 2 is a diagrammatic illustration of the embodiment of FIG. 1 illustrating the machine in an extraction operation. 
     FIG. 3 is a diagrammatic illustration of the embodiment of FIG. 1 illustrating the machine in a soil transfer roll operation. 
     FIG. 4 is a diagrammatic illustration of a prior art machine utilizing an extraction process. 
     FIG. 5 is a diagrammatic illustration of a machine utilizing a soil transfer roll cleaning process. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is directed both to a method of cleaning surfaces and an apparatus for performing the method. In a broad sense as will subsequently be described, the cleaning process in accordance with the present invention includes dual modes of operation. 
     FIG. 1 illustrates an embodiment of a transportable floor surface cleaning machine  10  according to the present invention. More particularly, machine  10 , for illustrative purposes, is illustrated as a battery-powered walk-behind machine similar to those known in the art, including a cleaning solution tank  12  for containing a cleaning liquid  14 , such as a mixture of water and a cleaning chemical, a recovery tank  16 , a cleaning head  18 , a cleaning liquid dispensing system, and a soiled solution extraction system as further described herein. In operation, machine  10  is supported upon the ground surface  20  by drive wheels  22  and caster wheels  24 . Representative examples of battery-powered walk-behind carpet machines having a cleaning solution tank  12 , recovery tank  16 , cleaning liquid dispensing means, and a soiled solution vacuum extraction system include models 1510 and 1550 extractors manufactured by Tennant Company, Minneapolis, Minn. Cleaning head  18  is attached at a forward portion of the machine  10  via a positioning actuator (not shown). In alternative embodiments of the invention, cleaning head  18  may be attached at other portions of a machine. In an illustrated embodiment, cleaning head  18  in accordance with the present invention may be used in conjunction with one of such known walk-behind extractor machines and the like. 
     Referring to FIGS. 2 and 3, cleaning head  18  in one embodiment of the present invention, includes a cleaning medium  26  and associated drive assembly as is more particularly shown in detail in FIGS. 2 and 3. Drive assembly includes drive motors  28  and belts  30  to rotate cleaning medium  26  relative to cleaning head  18  and surface  20 . In the illustrated embodiment, cleaning medium  26  includes a pair brushes  32  for use in an extraction mode of operation (as depicted in FIG. 2) and a pair of soil transfer rolls  34  for use in a soil transfer roll mode of operation (as depicted in FIG.  3 ). As described in more detail hereinafter, cleaning medium  26  may alternatively include a combination brush/soil transfer roll suitable for use in both modes of operation. Brushes  32  and soil transfer rolls  34  of cleaning medium  26  are rotatably driven by cleaning medium drive assembly including drive belts  30  and electric motors  28 . 
     Cleaning head  18  further includes two sets of spray nozzles  36 ,  38  for spraying cleaning solution  14  on the brushes  32 , soil transfer rolls  34  and/or floor surface  20 . The discharge of solution through roll spray nozzles  36  and floor spray nozzles  38  is controlled by activation of valves  40 ,  42 . A fluid pump  46  is provided to pressurize cleaning solution  14 . 
     In an exemplary embodiment of the invention, cleaning solution dispensing system includes pump  46  for selectively pumping cleaning liquid  14  through conduits  48 ,  50 ,  52  and nozzles  36 ,  38  thereby delivering cleaning liquid  14  to floor surface  20 , soil transfer rolls  34 , and/or brushes  32 . Appropriate fluid controls, such as valves  40 ,  42  switches (not shown), etc. are provided to control the application of cleaning fluid  14 . As depicted in FIG. 2, floor spray nozzle  38  discharges cleaning solution  14  to floor surface  20  and front extractor brush  32 . As depicted in FIG. 3, roll spray nozzle  36  discharges cleaning solution  14  to soil transfer rolls  34  during a soil transfer roll mode of operation. Alternative dispensing means may include drip bars or gravity feed techniques, transfer rolls, etc. 
     Cleaning head  18  further includes a plurality of vacuum extraction tools  54 ,  56 ,  58  for removing soil solution from either the floor surface  20 , the soil transfer rolls  34 , or both. Extractors  54 ,  56 ,  58  each include an elongated slot and an outlet aperture. Extractors  56 ,  58  share a common outlet aperture  60 . As depicted in FIG. 2, floor surface engaging extractor  54  is coupled to the vacuum system during an extraction mode of operation. Extractor  54  is configured to remove soiled solution from floor surface  20 . As depicted in FIG. 3, extractors  56 ,  58  are configured to remove soiled solution from soil transfer rolls  34 . Extractors  56 ,  58  are sized in relation to soil transfer rolls  34  to remove soiled solution across substantially the entire transverse length of the rolls  34 . An alternative vacuum extractor system may include two separate outlets each having a separate conduit to recovery tank  16 . 
     In operation, extractors  54 ,  56 ,  58  are selectively coupled to a vacuum-based solution recovery system including recovery tank  16  for soiled solution and vacuum fan  62 . A vacuum conduit  64  may be selectively connected to either the floor surface engaging extractor  54  (FIG. 2) or the pair of roll extractors  56 ,  58  (FIG.  3 ). Vacuum conduit  64  may be connected between the different extractors  54 ,  56 ,  58  by manually switching conduit  64 . Other manual valving may be practicable to make the connections in the vacuum recovery system. In another embodiment, vacuum connections of the soiled solution recovery system may be automatically performed, such as via a controlled valve, etc. 
     Referring again to FIG. 2, extractor brushes  32  may be bristle-type cylindrical brushes as known in the art. Referring to FIG. 3, soil transfer rolls  34  may of a variety of different materials. A combination of pad-like or bristle-like or foam-like materials, and the like, may be used. In a preferred embodiment a material such as a woven synthetic fabric, having pile fibers tufted thereunto is utilized. In one embodiment of the invention, the substrate has an appearance and feel that is similar to the surface fabric used on a common paint roller. In some instances, it may be desirable to intersperse stiffer fibers, i.e., brush-like bristles, into the substrate to enhance the agitation action of soil transfer rolls  34 . It is further envisioned that a single “hybrid” roll design may be utilized during both modes of operation. A hybrid roll/brush design may contain aspects of a bristle brush and soil transfer roll material (fabric, pile structures, etc.). A hybrid roll design would eliminate the requirement of switching rolls  34  with brushes  32  during operational mode changes. 
     Operation of machine  10  will now be described. In operation, machine  10  is propelled across surface  20 . To initiate a cleaning operation, appropriate controls  65 , such as switches, are used to activate vacuum fan  62 , motors  28 , valves  40 ,  42 , cleaning liquid pump  46 , etc. At least two modes of operation are available, an extraction mode and a soil transfer roll mode. Switching between the two modes may entail a change of vacuum connections between extractors  54 ,  56 ,  58  and recovery tank  16 , activation of valves  40 ,  42 , and switching brushes  32  with soil transfer rolls  34 . 
     In the extraction mode of operation (as depicted in FIG.  2 ), machine  10  functions similarly to known carpet extractors. Machine  10  operates in a direction as indicated by arrow  66 . Cleaning solution  14  is pressurized by pump  46  and directed through valve  40  and conduit  52  to floor spray nozzle(s)  38 . Cleaning solution discharged through nozzle(s)  38  is directed primarily onto the floor surface  20 . Nozzle(s)  38  may also direct some cleaning solution onto front extractor brush  32 . Extractor brushes  32  are driven via motors  28  to engage the floor surface and transfer soil into a soiled cleaning solution. Brushes  32  may include bristles to facilitate soil transfer. The direction of brush rotation is indicated by arrows  68 ,  70 . As cleaning machine progresses across the floor surface  20 , floor extractor  54  engages the wetted portion of the floor to remove soiled solution from the surface. Soiled solution is moved through vacuum conduit  64  and into recovery tank  16  by operation of vacuum fan  62 . 
     A description of a second mode of operation, a soil transfer roll mode, may be made with reference to FIG.  3 . One or more transfers between the two modes of operation may occur during a machine usage, e.g., an operator may perform the extraction process on a portion of a floor surface and perform the soil transfer roll process on another portion of the floor surface. 
     In the second mode of operation, soil transfer rolls  34  are wetted with cleaning liquid  14  by cleaning solution nozzle  36 , then extracted by operation of roll extractors  56 ,  58  to remove soiled cleaning liquid, and then wiped against floor surface  20  so as to transfer soil from surface  20  onto soil transfer rolls  34 . Soil transfer rolls  34  revolve by operation of motors  28  in directions as indicated by arrows  68 ,  70  so that different portions of the soil transfer rolls  34  are being wetted with cleaning liquid  14 , extracted by roll extractors  56 ,  58 , or wiped against surface  20 . 
     In this second mode of operation, cleaning solution is pressurized via pump  46  and flows through valve  42  and conduit  50  toward roll nozzle(s)  36 . Cleaning solution usage (solution volume/area of floor surface) during the second mode of operation (soil transfer roll cleaning) may be substantially less than during the first mode of operation (hot water extraction). Floor spray nozzle  38  may be optionally activated during the second mode of operation to increase the amount of solution  14  applied to floor  20 . 
     In the soil transfer roll mode of operation, wetted portions of rolls  34  may be defined as those roll portions which receive cleaning liquid from the spray nozzle  36 . Vacuum extractors  56 ,  58  each engage a roll  34  to remove some of the just deposited cleaning liquid  14  and soil previously transferred from the carpet surface  20 . Each roll  34  is engaged by its associated vacuum extractor  56 ,  58  to reduce the local wetness of the roll  34 . As a result, rotating rolls  34  have a wetted portion as defined above, and a reduced wetness portion which engages the carpet surface  20 . 
     As rolls  34  are revolved, reduced wetness portions engage the carpet fibers and cause soil to be transferred from the carpet fibers to rolls  34 . As rolls  34  are further rotated, the reduced wetness portions (having received soil from the carpet) are sprayed with cleaning liquid  14  by nozzle  36  and subsequently vacuum extracted by extractors  56 ,  58  to convey soiled cleaning liquid from rolls  34  into soiled solution recovery tank  16 . 
     The soil transfer roll cleaning process thus includes the steps of wetting a portion of rolls  34  with cleaning liquid  14 , reducing the relative wetness of the wetted portion of the rolls  34  by extraction, and wiping the surface with the rolls  34  so as to transfer soil from the surface to the rolls  34 . Soil upon the rolls  34  is subsequently removed as the revolving rolls  34  are rewetted and extracted. In turn, the soil transfer roll cleaning process repeats as a cycle with rolls  34  revolving so that cleaning liquid  14  is applied to one portion, extractors  56 ,  58  reduce the relative wetness of another portion of rolls  34  (and removing soiled solution therefrom), and yet another portion of rolls  34  wipe the surface  20  to transfer soil from the surface to the rolls  34 . 
     Additional aspects of the present invention will be addressed. It is envisioned that the cleaning processes according to the present invention may be performed on a variety of different machines, ranging from small manually operated devices, to large operator driven vehicles. The illustrated device is a walk-behind type cleaning machine, more particularly a battery powered self-propelled machine. In alternative embodiments, machine  10  may be propelled by an operator or may include a vehicle, such as a ride-on or towed-behind vehicle. Machine  10  may be powered through battery power, as shown, through alternating current supplied through a cord, or through another type of on-board power source, such as an IC engine. 
     Embodiments of the present invention may be utilized for cleaning a variety of floor surfaces, including but not limited to carpets, rugs, tile, vinyl, terrazzo, wood floors, and concrete surfaces. Additional surfaces which may be cleaning through a process as described herein include walls, stairways, upholstered furniture or fabric, such as curtains and the like. In a particularly preferred embodiment and as described herein with reference to machine  10  operation, the present invention is utilized for cleaning floor coverings. 
     In another embodiment soil transfer rolls  34  may be cylindrical shaped elements having a combination of foam and bristle surfaces (not shown). Rolls  34  may include a variety of different materials including fabrics, synthetic scouring pads, foam elements, monofilament fibers for enhancing agitation of the carpet, and the like which serve the intended function of transferring soil from a surface being wiped onto the soil transfer roll  34 . 
     Extractors  54 ,  56 ,  58  may be provided by a wide array of structures and techniques as may be appreciated by those skilled in the relevant arts. One particular extractor technology is disclosed in U.S. application Ser. No. 10/236,746, entitled “Fluid Recovery Device”, assigned to Tennant Company, and incorporated in its entirety herein by reference. 
     Further, although a preferred cleaning solution dispensing means includes a pump  46 , other arrangements are of course possible so as to achieve the intended function of conveying cleaning solution  14  during the cleaning processes. Additionally, the cleaning liquid may comprise any cleaning solution which assists the transfer of the soil on the surface onto the cleaning medium. For example, cleaning liquid  14  could also be in the form of a foam, vapor, liquid with suspended solids, a granular cleaning material, plain water, and the like. 
     Other modifications to the described embodiment may also be practicable. One or more cleaning liquid dispensing devices may be utilized in alternative embodiments of the invention. Additionally, vacuum extractor tools  56 ,  58  may be alternatively configured. For example, a plurality of vacuum extracting locations may be practicable, i.e., a first vacuum extraction location for reducing the relative dampness of the rotating cleaning medium prior to contact with the floor surface, and a second vacuum extraction location for removing soiled solution from the cleaning medium. 
     Other embodiments of the present invention may position vacuum extractor tools  56 ,  58  at different locations as compared to FIGS. 1-3. For example, it may be desirable to extract a portion of cleaning implement  34  after that portion is wiped against the carpet. In this manner, the steps of operation would include wetting a portion of cleaning implement  34 , wiping that portion of cleaning implement  34  against the carpet surface, and then extracting that portion to removed soiled cleaning solution. A modification to the illustrated embodiment of FIGS. 1-3 could entail positioning extractors  56 ,  58  between motors  28 . Other positions of extractors  56 ,  58  may also be practicable. Extractors  54 ,  56 ,  58  may each be independently movable between an operational position and a nonoperational position. For example, extractor  54  may engage carpet surface  20  as indicated in FIG. 2 during a first mode of machine operation and be moved away from carpet surface  20  as indicated in FIG. 3 during a second mode of operation. In another example, extractors  56 ,  58  may be selectively moved relative to rolls  34  and/or brushes  32  to increase or decrease the distance between the elements. The positioning of extractors  54 ,  56 ,  58  may be electro-mechanically or manually controlled. 
     Other embodiments of the present invention may utilize a different drive system to power rolls  34  and/or brushes  32 . A single electric motor may be one option. Mounting and support structures for the rolls  34  and/or brushes  32  may also vary. Rolls  34  may be held upon a wire frame, similar to a paint roller, and allow for removal from one side of the machine. Other roll  34 /brush  32  connections would be appreciated by those of ordinary skill in the arts. The direction of rotation of rolls  34 /brushes  32  may be altered from that illustrated in the preferred embodiment. Three or more rolls  34  and/or brushes  32  may be practicable. Roll  34  and brush  32  rotational speed may be selectively controlled so that speeds differ between differ modes of operation. Down pressure of rolls  34  and brushes  32  may be selectively controlled so that the down pressures differ between modes of operation. Additional spray nozzles may be desirable to convey cleaning solution  14  to rolls  34 , brushes  32 , or surface  20 . A system may be provided to momentarily increase the application of cleaning solution  14  to the various components or surface  20 . Such a system may include a button or other switch to activate additional nozzles, etc. for a predetermined period of time. 
     In the preferred embodiment of the invention as illustrated in FIG. 1, the revolving cleaning implement is roll  34 . Roll  34  may be constructed of nylon fibers secured to a polypropylene core. Other materials or material combinations would be appreciated by those of ordinary skill in the arts. In alternative embodiments, the revolving cleaning medium may be a belt (not shown). A belt comprised of a substrate, such as a woven synthetic fabric, having pile fibers tufted thereinto may be practicable. In some instances it may be desirable to tuft stiffer monofilament fibers into the fabric substrate to enhance the agitating action of the belt. The softer pile fibers tufted into the fabric serve to carry cleaning liquid, while the stiffer monofilament fibers serve to scrub the carpet. The belt may be supported between rollers and driven via a variety of known approaches. U.S. Pat. No. 6,145,145, incorporated by reference herein, discloses a belt technology which may be applicable to the present invention. 
     Definitions are provided herein with reference to terms used in the specification and appended claims: 
     “Cleaning Medium”: a part, component, assembly, or structure capable of engaging a carpet or other surface in a wiping manner and accepting soil from the carpet or other surface. A cleaning medium may assume a variety of shapes, including but not limited to roll-like brushes, belts, disk-shaped elements, etc. A cleaning medium may consist of a variety of different materials of construction, such as absorbent and nonabsorbent materials, bristle-type materials, abrasive elements, fabric, etc. 
     “Revolving”: Tending to revolve or happen repeatedly, available at regular intervals. As used herein, the term broadly describes a cyclical movement of the cleaning medium relative to surface  20 . A cylindrical shaped “revolving” cleaning medium may be rotate about an axis of rotation. A belt shaped “revolving” cleaning medium may be supported for movement about a pair of rollers, etc. 
     “Extracting”: Drawing or pulling out, using force or effort, to remove or obtain from a substrate by mechanical action, as by mechanical pressure or vacuum. As used herein, the term broadly describes the step of removing cleaning liquid and/or soil from the rolls  34  or surface  20 . The step of extracting may be achieved through a mechanical shearing type operation, or a vacuum removal operation, or both. 
     “Wipe”: To rub against or otherwise engage a surface in a moving manner. As used herein, the term broadly describes physical engagement between the cleaning medium and surface  20 . In one mode of machine operation, rolls  34  engage surface  20  in a “wiping” manner to transfer soil from surface  20  to roll  34 . Wiping does not necessarily imply or suggest removing liquid from surface  20 . Cleaning rolls  34  when wiped against the carpet surface may transfer some cleaning liquid to the carpet surface. 
     As various changes could be made in the above methods and devices without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.