Patent Publication Number: US-10765286-B2

Title: Surface maintenance machine

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 15/374,349, filed Dec. 9, 2016, which claims the benefit of U.S. Provisional Patent Application No. 62/265,063, filed Dec. 9, 2015, and U.S. Provisional Patent Application No. 62/360,661, filed Jul. 11, 2016, the entire contents of each of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     Surface maintenance machines for relatively large floor areas, for example, of commercial, industrial, public or institutional spaces, are typically integrated with an operator-driven vehicle. These machines can be a floor scrubbing machine or a floor sweeping machine. Other machines, such as polishing, burnishing or outdoor litter collecting machines can also perform other surface maintenance operations such as cleaning (e.g., sweeping, scrubbing, etc.) polishing, burnishing, buffing, stripping and the like on surfaces such as floors, hallways, etc. of buildings, roads, pavements, sidewalks and the like. 
     Some such surface maintenance machines are commercially available “micro” rider machines, allowing an operator to stand on a platform. Some of these machines have a centrally located front wheel and two rear wheels, with the operator platform inset between the rear wheels. In such machines, a common way to steer and propel a wheel (typically the centrally located front wheel) is by using a wheel motor rotatable by means of a steering linkage. In such machines, the location of the center of gravity should be accounted for to provide stability during normal vehicle operation (e.g., braking during turning). 
     Moreover, known mechanisms to steer and propel three-wheeled machines, such as using independently driven wheels (e.g., differential steering), can often lead to higher complexity. Prior three wheeled machines with two front wheels and one rear wheel have used steerable rear wheels which may lead to rear swing, which may cause portions of the vehicle to move in a direction opposite to the direction of turn. Rear swing may be undesirable when maneuvering next to objects (walls, curbs, buildings, people, etc.). Another known mechanism for three-wheeled vehicles includes a steerable single front wheel and two rear wheels propelled by a transaxle. This mechanism does not allow for a zero turn (e.g., a turn of zero turning radius). Other ways of steering a three-wheeled machine with two front wheels and a single rear wheel machine include providing a steering linkage connecting the two front wheels. As the steering linkage does permit sufficient steering rotation, such a mechanism would not permit a zero turn. 
     SUMMARY 
     In one aspect, this disclosure is directed to a surface maintenance machine comprising a maintenance head assembly with one or more surface maintenance tools for performing a surface maintenance operation. The machine comprises two front wheels, at least one of which is steerable. The two front wheels can be positioned to the front of a transverse centerline of the machine when the machine is moving in a forward direction. The machine further comprises at least one rear wheel positioned to the rear of the transverse centerline. The rear wheel can be interior to the front wheels. The machine may include a motive source for providing motive force to at least one front wheel to drive the machine on a surface. 
     In another aspect, the surface maintenance machine comprises two front wheels positioned to the front of a transverse centerline of the machine when the machine is moving in a forward direction and a rear wheel positioned to the rear of the transverse centerline. The rear wheel can be positioned generally to the center of the machine. The machine further comprises an operator platform configured for allowing an operator (e.g., adult operator) to stand thereon. The operator platform can be positioned to the rear of the transverse centerline of the machine. The operator platform can be forward and rearward of the rotational axis of the rear wheel. The operator platform can extend at least partly around the rear wheel and laterally outwardly from the sides of the rear wheel for supporting an operator in a standing position with the operator&#39;s feet on either side of the rear wheel. 
     In yet another aspect, a longitudinal centerline of the machine may extend through the rear wheel at a lateral center point of the rear wheel and the front wheels can be positioned on opposite sides of the longitudinal centerline, such that the first and second front wheels and the rear wheel form a triangle. Further, a center of gravity of the machine can be positioned in the front one-third of the machine and projected to fall within the triangle formed by the first and second front wheel and the rear wheel when the operator is not standing on the platform, such that the position of the center of gravity remains generally within the triangle formed by the first and second front wheels and the rear wheel when the operator is standing on the operator platform and the machine is being operated normally. 
     The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1A  is a perspective view of a surface maintenance machine according to an embodiment; 
         FIG. 1B  is a perspective view of the surface maintenance machine of  FIG. 1A  with some body panels removed to illustrate internal detail; 
         FIG. 2  is a bottom plan view of the surface maintenance machine of  FIG. 1B ; 
         FIG. 3  is a schematic view of the front and rear wheels of the surface maintenance machine of  FIG. 1B ; 
         FIG. 4A  is a schematic of a the front and rear wheels of the surface maintenance machine of  FIG. 1B ; 
         FIG. 4B  is a schematic of conventional three-wheeled surface maintenance machines; 
         FIG. 5  is a rear perspective view of the surface maintenance machine of  FIG. 1B ; 
         FIG. 6  is a cross-sectional side perspective view of a rear portion of the surface maintenance machine taken along the plane  6 - 6  shown in  FIG. 5 ; 
         FIG. 7  is a top view of the rear portion of the surface maintenance machine shown in  FIG. 6 ; 
         FIG. 8  is a perspective view of a maintenance head assembly of the present disclosure according to an embodiment when the machine is traveling in a generally straight path; 
         FIG. 9  is a top plan view of the maintenance head assembly of  FIG. 8 ; 
         FIG. 10  is a perspective view of a maintenance head assembly of  FIG. 8  when the machine turns; 
         FIG. 11  is a top plan view of the maintenance head assembly of  FIG. 10 ; 
         FIG. 12  is a perspective view of a maintenance head assembly of the present disclosure according to another embodiment when the machine is traveling in a generally straight path; 
         FIG. 13  is a top plan view of the maintenance head assembly of  FIG. 12 ; 
         FIG. 14  is a perspective view of a maintenance head assembly of  FIG. 12  when the machine turns; 
         FIG. 15  is a top plan view of the maintenance head assembly of  FIG. 14 ; 
         FIG. 16  is an articulating mechanism for the squeegee assembly for the maintenance head assembly disclosed in the present application; 
         FIG. 17  is a cross-sectional side view of the articulating mechanism of  FIG. 16 ; 
         FIG. 18  is an enlarged side view of the squeegee assembly. 
         FIG. 19  is a perspective view of the surface maintenance machine of  FIG. 1  illustrated with an operator and manual maintenance tools; 
         FIG. 20  is a side perspective view of the surface maintenance machine of  FIG. 1  with an access door shown in an open position to illustrate interior storage areas; 
         FIG. 21  is another side perspective view of the surface maintenance machine of  FIG. 1  with top and front portions of the machine body shown in an open position to illustrate interior portions thereof; 
         FIG. 22  is another side perspective view of the surface maintenance machine of  FIG. 1  shown with two access doors; and 
         FIGS. 23A, 23B and 23C  are schematics illustrating a modular storage chamber positioned within the body of the surface maintenance machine. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1A  is a perspective view of an exemplary surface maintenance machine  100 .  FIG. 1B  illustrates the surface maintenance machine  100  with some body panels removed for clarity. In the illustrated embodiment shown in  FIG. 1B , the surface maintenance machine  100  is s a ride-on machine  100 . The surface maintenance machine  100  can perform maintenance tasks such as sweeping, scrubbing, polishing (burnishing) a surface. The surface can be a floor surface, pavement, road surface and the like. Embodiments of the surface maintenance machine  100  include components that are supported on a mobile body  102 . As best seen in  FIG. 1B , the mobile body  102  comprises a frame  104  supported on wheels for travel over a surface, on which a surface maintenance operation is to be performed. The mobile body  102  may include operator controls (not shown) and a steering control such as a steering wheel  108  such that an operator  109  can turn the steering wheel  108  and control the speed of the machine  100  without having to remove the operator&#39;s hands from the steering wheel  108  using means well-known in the art. The machine can perform maintenance on a maintenance path which can have an area corresponding to an envelope defined by the front surface  112 , back surface  114  and two lateral surfaces  116  and  118  of the machine  100  as the machine travels on a surface  120 . 
     The surface maintenance machine  100  can be powered by an on-board power source such as one or more batteries or an internal combustion engine (not shown). The power source can be proximate the front of the surface maintenance machine  100 , or it may instead be located elsewhere, such as within the interior of the surface maintenance machine  100 , supported within the frame  104 , and/or proximate the rear of the surface maintenance machine  100 . Alternatively, the surface maintenance machine  100  can be powered by an external electrical source (e.g., a power generator) via an electrical outlet or a fuel cell. The interior of the surface maintenance machine  100  can include electrical connections (not shown) for transmission and control of various components. 
     While not shown in detail in  FIG. 1B , the surface maintenance machine  100  includes a maintenance head assembly  400 . The maintenance head assembly  400  houses one or more surface maintenance tools such as scrub brushes, sweeping brushes, and polishing, stripping or burnishing pads, and tools for extracting (e.g., dry or wet vacuum tools). For example, the maintenance head is a cleaning head comprising one or more cleaning tools (e.g., sweeping or scrubbing brushes). Alternatively, the maintenance head is a treatment head comprising one or more treatment tools (e.g., polishing, stripping or buffing pads). Many different types of surface maintenance tools are used to perform one or more maintenance operations on the surface  120 . The maintenance operation can be a dry operation or a wet operation. Such maintenance tools include sweeping, scrubbing brushes, wet scrubbing pads, polishing/burnishing and/or buffing pads. Additionally, one or more side brushes for performing sweeping, dry or wet vacuuming, extracting, scrubbing or other operations can be provided. The maintenance head assembly  400  can extend toward a surface on which a maintenance operation is to be performed. For example, the maintenance head assembly  400  can be attached to the base of the surface maintenance machine  100  such that the head can be lowered to an operating position and raised to a traveling position. The maintenance head assembly  400  is connected to the surface maintenance machine  100  using any known mechanism, such as a suspension and lift mechanism such as those illustrated in U.S. Pat. No. 8,584,294 assigned to Tennant Company of Minneapolis, Minn., the disclosure of each of which is hereby incorporated by reference in its entirety. 
     In some embodiments, the interior of the surface maintenance machine  100  can include a vacuum system (not shown) for removal of debris from the surface. In such embodiments, the interior can include a fluid source tank (not shown) and a fluid recovery tank (not shown). The fluid source tank can include a fluid source such as a cleaner or sanitizing fluid that can be applied to the surface  120  during treating operations. The fluid recovery tank holds recovered fluid source that has been applied to the surface  120  and soiled. The interior of the surface maintenance machine  100  can include passageways (not shown) for passage of debris and dirty liquid. In some such cases, the vacuum system can be fluidly coupled to the recovery tank for drawing dirt, debris or soiled liquid from the surface. The vacuum system may comprise a vacuum-assisted squeegee (to be described with respect to  FIGS. 8-18 ) mounted to extend from a lower rearward portion  132  of machine  100 . Fluid, for example, clean liquid, which may be mixed with a detergent, can be dispensed from the scrubbing fluid tank to the floor beneath machine  100 , in proximity to the scrubbing brushes, and soiled scrubbing fluid is drawn by the squeegee centrally, after which it is suctioned via a recovery hose into the recovery tank. Machine  100  can also include a feedback control system to operate these and other elements of machine  100 , according to apparatus and methods which are known to those skilled in the art. 
     In alternative embodiments, the surface maintenance machines  100  may be combination sweeper and scrubber machines  100 . In such embodiments, in addition to the elements describe above, the machines  100  may either be an air sweeper-scrubber or a mechanical sweeper-scrubber. Such machines  100  can also include sweeping brushes (e.g., rotary broom) extending toward a surface (e.g., from the underside of the machine  100 ), with the sweeping brushes designed to direct dirt and debris into a hopper. In the cases of an air sweeper-scrubber, the machine  100  can also include a vacuum system for suctioning dirt and debris from the surface  120 . In still other embodiments, the machine  100  may be a sweeper. In such embodiments, the machine  100  may include the elements as described above for a sweeper and scrubber machine  100 , but would not include the scrubbing elements such as scrubbers, squeegees and fluid storage tanks (for detergent, recovered fluid and clean liquid). 
     In use, an operator may ride the machine  100  in a standing position and stand on an operator platform  190 . The operator platform  190  can optionally include one or more foot pedals  122 ,  124  for engaging with maintenance tools  406  extending from below the machine  100 , as will be described further below. Continuing with the illustrated embodiment of  FIG. 1B , advantageously, the machine  100  includes an operator console  126  provided on the machine  100  body. The operator console  126  can include controls for steering, propelling, and controlling various operations of the machine  100 . For instance, the operator console  126  can include a steering control such as a steering wheel  108  such that an operator standing on the operating platform can grasp and turn the steering wheel  108  to turn the machine  100 . Further, the operator console  126  can include speed controls (e.g., such as a knob, not shown) that can control the speed of the machine  100  without having to remove the operator&#39;s hands from the steering wheel  108  using means well-known in the art. As is apparent from the foregoing disclosure, the operator console  126  can be approximately at the waist-level of an adult operator standing on the operating platform. Such embodiments allow a compact vehicle design while providing easy to use controls to control the operation of the machine  100 . 
     Continuing with  FIG. 1B , the surface maintenance machine  100  according to some embodiments can have an overall width  139  of less than about three feet. For example, the machine  100  can have an overall width  139  of less than about 28 inches. As used herein, the term “width” refers to the distance between lateral surfaces  116 ,  118 (e.g., perpendicular to the longitudinal centerline and/or the transverse centerline  158 ) of the machine  100 . The lateral confines of the machine  100  in such cases are within about 28 inches. In such cases, the machine  100  has a maintenance path corresponding to an envelope of the surface in contact with the maintenance head assembly  400  during a surface maintenance operation. The envelope as used herein can be the area defined by the front surface  112 , back surface  114  and two lateral surfaces  116  and  118  of the machine  100 . The maintenance path can have a width (e.g., distance between lateral surfaces  116  and  118 ) of between about 20 inches and about 24 inches. Such machines  100  are sometimes referred to as “micro-riders” because of their compact sizes. While an exemplary micro-rider machine is illustrated, the embodiments disclosed herein can apply similarly to machines of any sizes and configuration. 
     With continued reference to  FIG. 1B , in certain embodiments, the machine  100  comprises three wheels. In the illustrated embodiment, the machine  100  comprises a steerable front wheel  140 , and a non-steerable front wheel  142 . As shown herein, the steerable front wheel  140  and non-steerable front wheel  142  are positioned toward a lower front portion  144  to the front of a transverse centerline  146  of the machine  100  when the machine  100  is moving in a forward direction  148 . As illustrated herein, the transverse centerline corresponds to a line positioned about one-half of the distance  182  between the front wheels  140 ,  142  and rear wheel  150 . Also illustrated in  FIG. 1B  is a rear wheel  150  positioned near the lower rearward portion  132  to the rear of the transverse centerline  146  of the machine  100  when the machine  100  is moving in a forward direction  148 . In some cases, rear wheel  150  comprises a unitary wheel (e.g., one-piece design). For example, in some cases, there may be no other wheels to the rear of the transverse centerline  146  except for a single rear wheel  150 . While the rear wheel  150  is shown as being centered on the longitudinal centerline  154  of the machine, small offsets from the central location are still contemplated by the illustrated embodiments, and the rear wheel  150  may not have equal portions extending on opposite sides of the longitudinal centerline  154 . 
     In the embodiments illustrated herein, the front wheel  140  is steered, while the non-steerable front wheel  142  trails along and turns as the machine  100  is turned. Alternatively, both front wheels  140 ,  142  can be steered. In embodiments disclosed herein, at least one of the front wheels  140 ,  142  is steered, while the rear wheel  150  may or may not be steered. While the following description is described relative to steering the front wheel  140 , it should be noted that both front wheels  140 ,  142 , and rear wheels  150  can be steered in a manner similar to the operation described relative to front wheel  140  below. 
     The machine  100  comprises a steering assembly having a steering wheel  108  coupled to (e.g., via a steering column and rack and pinion steering mechanism, or other such steering mechanisms known in the art) the steerable front wheel  140 . By turning the steering wheel  108 , the front wheel  140  can be turned to turn the machine  100  around a corner. The front wheel  140  can be turned by any angle to complete a turn having a desired angle (e.g., less than or equal to 90 degrees), as will be explained further with respect to  FIG. 3 . Such embodiments can be beneficial in allowing a greater degree of freedom for the steerable-front wheel  140 , thereby permitting the machine  100  to be used for maintaining surfaces in narrow spaces (e.g., hallways or aisles with width under about three feet, enter or leave doorways having a width of about 28 inches, perform a zero turn in an aisle of width about 60 inches and the like). 
     Referring now to  FIG. 2 , the machine  100  can include a motive source  152  for providing motive force to the steerable front wheel  140  to drive the machine  100  on a surface  120 . The motive source  152  can be positioned proximal to and coupled to (e.g., directly or via a transmission system) the front wheels  140 ,  142 . As such, the illustrated embodiments represent a front wheel  140  drive and a front steered vehicle. The rear wheel  150  in such cases can be neither steered nor propelled, thereby allowing for the rear wheel  150  to remain substantially stationary when the machine  100  is turned by an operator. The rear wheel  150  in some embodiments can be a non-marking wheel (e.g., made of a material that is resilient relative to the frame  104  of the machine  100 ) to reduce wheel marks on the surface  120  being maintained. For example, as shown in  FIG. 2 , the machine  100  can include a motor coupled the steerable front wheel  140  to drive the front wheel  140 . In such cases, the non-steerable front wheel  142  may not be propelled by the motive source  152 . For example, the non-steerable front wheel  142  can be a caster and remain non-steered and non-driven during normal operation of the machine  100  and merely turn or rotate to facilitate moving the machine  100 . As will be further explained below, embodiments such as those illustrated in  FIG. 2  can offer improved stability and reduce “rear swing” over other three-wheeled drive and steering systems of machines  100  known in the art, especially when the machine  100  is being turned around a sharp turn (e.g., 90 degrees or more) with respect to the forward direction  148  of the machine  100 . 
     Alternatively, the motive source  152  can propel the rear wheel  150 . In such cases, the rear wheel  150  may or may not be steerable, while one or more of the front wheels  140 ,  142  can be steerable. Any configuration of steering and propelling of the wheels are contemplated, and the embodiments described herein are not limited to the illustrated embodiment shown in  FIG. 2 . For example, the two front wheels  140 ,  142  can each steerable by a steering mechanism (e.g., a single steering mechanism steering two front wheels). Similarly, both front wheels  140 ,  142  can be propelled by the motive source  152  for providing motive force to the front wheels. Alternatively, at least one of the front wheels  140 ,  142  are steerable by a steering mechanism, and the rear wheel  150  is non-steerable, but can be propelled by a motive source for providing motive force to the rear wheel  150 . 
     During use, an operator may have to turn the machine  100  to perform a surface  120  maintenance operation, or to travel to a different surface. For example, an operator may turn the machine  100  less than or equal to about 180 degrees (e.g., a left turn, a right turn or a U-turn) from the forward direction  148  in a narrow aisle. In such cases, to improve the stability of the machine  100  and also to reduce rear swing, in the embodiments described herein, the rear wheel  150  is neither driven by the motive source  152 , nor steered. The machine therefore pivots about a stationary pivot point  220  when turned. When an operator turns the machine  100  by a desired angle (e.g., 90 degrees), the machine  100  turns about the stationary pivot point  220  by the desired angle. As the rear wheel  150  is not driven or steered, its chances of traversing a path having a radius of curvature different from (e.g., wider than) the radius of curvature of the turn are reduced. Such embodiments reduce rear swing and any damage due to collision of the rear of the machine  100  with any obstruction to the rear of the transverse centerline  146  of the machine  100  (e.g., walls, etc.) as the machine  100  is cleaning in the proximity of an obstruction, such as along a wall or around a corner. 
     Continuing with the above, the stationary pivot point is at the intersection of a longitudinal centerline  154  of the machine and a rotational axis  151  of the rear wheel  150 . In some cases, the rear wheel  150  can be an idler wheel. In such cases, the rotational axis  151  of the rear wheel  150  is parallel to the transverse centerline  146  of the machine when the machine turns. Alternatively, in some embodiments, the rear wheel  150  can pivot to a limited extent. In such cases, the rotational axis  151  of the rear wheel  150  is passively pivotable relative to the transverse centerline  146  of the machine. In such cases, the rear wheel  150  is non-steerable and is not propelled, but may pivot to a limited extent similar to a caster. Still further, the rear wheel  150  can be actively steered (e.g., by the steering mechanism and/or a transaxle) and/or propelled (e.g., by the motive source  152 ). In examples where the rear wheel  150  is actively steered, the rotational axis  151  is actively pivotable with respect to the transverse centerline  146  of the machine by a steering mechanism and/or a transaxle. 
     With continued reference to  FIG. 2 , the rear wheel  150  is generally centered about a longitudinal centerline  154  of the machine  100  such that the rear wheel  150  extends on two opposite sides of the longitudinal centerline  154 . As used herein “generally centered” includes small offsets of the rear wheel  150  relative to the longitudinal centerline such that portions of the rear wheel  150  that extend on either side of the longitudinal centerline  154  may not be exactly equal. As illustrated herein, the longitudinal centerline  154  can correspond to a line positioned about one-half of the distance  184  between the front wheels  140 ,  142 . The steerable and non-steerable front wheels  140 ,  142  may be positioned symmetrically or asymmetrically on either side of the longitudinal centerline  154  of the machine  100 . In such cases, as best seen in  FIG. 3 , the front and rear wheels  140 ,  142 ,  150  are arranged in a triangular orientation. When viewed from the bottom, each of the front and rear wheels  140 ,  142 ,  150  form a vertex of the triangle  156 , with the sides  158 ,  160  of the triangle  156  tapering from the front of the machine  100  to the rear. As will be described further below, such embodiments with two front wheels  140 ,  142  and a single rear wheel  150  can offer less sensitivity to center of gravity position over conventional three-wheeled surface maintenance machines (e.g., such as conventional machines having a single front wheel and two rear wheels). In such embodiments, there may be no other wheel other than the rear wheel  150  positioned to the rear of the transverse centerline of the machine that is inline with the rotational axis  151  of the rear wheel. Accordingly, the rear wheel  150  is centrally located such that it is symmetrically positioned on the longitudinal centerline  154  of the machine. In such a configuration, the machine  100  has three contact points with the surface  120 , each contact point corresponding to each of the front wheels  140 ,  142  and the rear wheel  150 . The contact points define a contact plane such that no other wheels except the three wheels  140 ,  142 , and  150  contact the surface  120  at the contact plane. 
     As referred to previously, the front wheel  140  is coupled to a steering wheel  108  to turn the machine  100  by a desired angle, while the rear wheel  150  remains stationary while turning. For instance, as the machine  100  is turned, it may pivot about the center of the stationary rear wheel  150 . As shown in  FIG. 3 , the steerable front wheel  140  (and the motive source  152  coupled thereto) can be offset with respect to the longitudinal centerline  154  of the machine  100 . One skilled in the art would recognize that as a result of this orientation, the front wheel  140  turns by a turning angle with respect to the longitudinal centerline  154  wherein the turning angle may be greater than the desired angle by which the machine  100  is to be turned. For example, in the illustrated embodiment, the front wheel  140  is turned by a turning angle greater than 90 degrees (e.g., between about 100 degrees and about 110 degrees) with respect to the longitudinal centerline  154  of the machine  100  to turn the machine  100  away from the longitudinal centerline in the direction  181  shown in  FIG. 3 . Moreover, if the front wheels  140 ,  142  are to be spaced further apart than by the distance  184  shown in  FIG. 3 , the turning angle of the steering wheel  108  increases further from the exemplary angles (e.g., greater than about 110 degrees) described herein in order to turn the machine  100  away from the longitudinal centerline (e.g., along arrow  181 ) by an angle of about 90 degrees. Similarly, the steering assembly is configured for steering the front wheel by an angle less 90 degrees with respect to the longitudinal centerline of the machine when turning the machine toward the longitudinal centerline (e.g., along the direction  183 ) by an angle of about 90 degrees. 
     With continued reference to  FIG. 3 , the triangular orientation of the front wheels  140 ,  142  and the rear wheel  150  permits a center of gravity  162  of the machine  100  to be suitably located. For instance, a projection of the center of gravity  162 , in the top plan view of  FIG. 3  is shown as being positioned substantially toward the front of the transverse centerline  146  and within the triangle  156  formed by the front and rear wheels  140 ,  142 ,  150 . As is apparent to one of ordinary skill in the art, when the projected position of the center of gravity  162  of the machine  100  lies within the triangular orientation of the front and rear wheels  140 ,  142 ,  150 , the machine  100  remains in stable equilibrium, and is undue instabilities during use of the machine  100  (e.g., braking during turning, etc.) may be reduced. Such undesirable effects may include excessive lateral acceleration due to centrifugal forces directed radially outward about the center of curvature of the turn that throws the operator outwardly while turning. In some exemplary embodiments, the machine  100  can be front-loaded to position its center of gravity  162  to the front of the transverse centerline  146  and within the triangle  156 . For example, heavier components of the machine  100  (e.g., scrub head, battery or other power source, motive source  152  such as motor) can be positioned to the front of the transverse centerline  146 . Such embodiments have a weight distribution wherein more of the machine  100 &#39;s weight is toward its front when an operator is not standing on the operator platform  190  and/or when solution tanks positioned to the front of the transverse centerline  146  comprising clean or dirty liquids are full, thereby moving the center of gravity  162  to the front of the transverse centerline  146  of the machine  100 . For instance, in some such cases, the center of gravity can be within the front one-third of the machine  100  (e.g., one-third of the distance  182  shown in  FIG. 3 ) and projected to fall within the triangle  156  formed by the first and second front wheels  140 ,  142 , and the rear wheel  150  when the operator is not standing on the platform  190 . In such cases, the position of the center of gravity can be configured to remain generally within the triangle  156  formed by the first and second front wheels  140 ,  142  and the rear wheel  150  when the operator is standing on the operator platform and the machine is being operated normally. As used herein, “normal operation” can refer to any of the following: being driven on a floor surface, braked, turned, braked during a turn, when solution tanks are empty, when the operator has at least one foot on the operator platform, performing one or more maintenance operations on the surface and the like. Such embodiments can also reduce the chances of the machine  100  (e.g., to the rear of the transverse centerline  146 ) having weight imbalances when an operator steps on or off from the operator platform  190 , and when the operator is standing on the platform  190 . For instance, embodiments such as those disclosed herein have reduced instabilities (e.g., tipping, one of the wheels losing contact with the surface, and the like) when the operator has one foot on the operator platform  190 . Additionally, the machine reduces instabilities (e.g., tipping, one of the wheels losing contact with the surface, and the like) when the operator has both their feet on the operator platform  190 , and when the machine turns, brakes during a turn or travels on an inclined surface. 
     When the weight of the machine  100  or the operator shifts (e.g., braking during turning or traveling on an inclined surface, etc.) by allowing the center of gravity  162  of the machine  100  to remain lower to the ground and to the front of the machine  100  (e.g., at position  162 ′ shown in  FIG. 4A ), turning moments (e.g., that could result in instabilities due to lateral forces overcoming gravitational forces acting on the center of gravity of the machine  100 ) are reduced as is well-known to one of ordinary skill in the art. For example, the projected position of the center of the gravity  162  is positioned in close proximity to the surface  120  such that the center of the gravity  162  is no greater than the lower one-half, and more preferably one-third of the machine height when an operator is standing on the operator platform  190 . In some such cases, the machine is stable when the operator is turning the machine (e.g., a zero turn) and/or braking while turning. In some such cases, and referring to  FIGS. 1B and 4A , components of the machine  100  can also be arranged such that the a lower portion  164  of the machine  100  below a major center plane  166  of the machine  100  is heavier relative to an upper portion  168  of the machine  100  to above the major plane  166  of the machine  100  when an operator is standing on the operator platform  190 . Such embodiments lower the center of gravity  162  so that its projected position is further toward the surface  120 , and reduce the machine  100  and/or the operator from experiencing dynamic instabilities during normal use of the machine  100  which can involve operations such as braking during turning, performing a zero turn, or other similar operations. During such operations, even if the weight of the machine  100  or the operator&#39;s position shifts, the projected position of the center of gravity  162  lies proximal to the surface  120  and within the lateral confines (e.g., sides  158 ,  160 ) of the triangular configuration of the front and rear wheels  140 ,  142 ,  150 . Such embodiments reduce the potential for the machine  100  to become unstable during routine use of the machine  100 . 
     With continued reference to  FIG. 3  and referring now to  FIG. 4A , the stability of the machine during turning (e.g., zero turns) or braking during turning can be illustrated by the geometric orientation of the front and rear wheels. As seen in  FIG. 3 , the rear wheel  150  is cylindrical in shape and has a first lateral side  170  and a second lateral side  172 . The front wheels  140 ,  142  are each oriented such that the sides  158 ,  160  from each of the front wheels  140 ,  142  abut the lateral sides  170 ,  172  of the rear wheel  150 . In such embodiments, the projected position of the center of gravity  162  is generally contained within the triangular area between the front and rear wheels  140 ,  142 ,  150  due to front loading the machine  100 . As a result, force and moment imbalances are reduced, thereby allowing the operator to ride, turn, brake during turn or travel over an inclined surface with increased safety. 
     Continuing with the above, the center of gravity  162  is positioned substantially toward the front of the transverse centerline  146  and projected to fall within the triangle  156  formed by the front wheels  140 ,  142  and the rear wheel  150  when the operator is standing on the operator platform  190  and performs at least one of turning, braking during a turn, or travel over an inclined surface. As shown by the schematic of  FIG. 4A , if for instance, an operator turns the machine and/or brakes during a turn, in an exemplary embodiment, the resulting braking force vector indicated by arrow  162 ′ is toward one of the front wheels when turning. 
     In conventional three-wheeled machines, a single front wheel  310  and two rear wheels  320 ,  330  form a triangle  366 , where the conventional three-wheeled machine has a longitudinal centerline  354  and a transverse centerline  346  as shown in  FIG. 4B . In this embodiment, when an operator brakes during a turn, the location of the center of gravity  362  is inherently connected to the stable operation of the machine. For instance, if an operator turns the machine and/or brakes during a turn, the resulting braking force vector indicated by arrow  362 ′ is toward the line between the front wheel and one of the rear wheels when turning and outside the triangle  366 . In contrast, in embodiments of the surface maintenance machine with two front wheels and a single rear wheel illustrated schematically by  FIG. 4A , the resulting braking force vector  162 ′ remains generally within the triangle  156 , and as result, has relatively improved stability while braking during a turn, ramp climbing or during a zero turn. During these operations of the machine, the machine generally resists various accelerations and decelerations better because of front wheels  140 ,  142  being wide set and have a substantially broad envelope to the front of the transverse centerline  146  due to two front wheels  140 ,  142  and a single rear wheel  150 . Accordingly, if the machine&#39;s normal operations such as turning, braking during a turn remains generally within the triangle  156 . The machine therefore has generally improved stability and resists a wheel (e.g., a front wheel inner relative to the radius of a turn) losing its contact with surface on which the machine operates due to moments about the center of gravity  162 . 
     Referring now to  FIG. 5 , the surface maintenance machine  100  comprises an operator platform  190  to allow an operator to stand thereon. The operator platform  190  can be positioned to the rear of the transverse centerline  146  of the machine  100 . The operator platform  190  extends around the rear wheel  150 , and laterally outwardly from the longitudinal centerline  154  for supporting an operator in a standing position with the operator&#39;s legs on either side of the rear wheel  150  as shown in  FIG. 1B . The rear wheel  150  can be positioned centrally with respect to the platform. In some such cases, the platform  190  optionally includes a cut-out portion  192 . The cut-out portion  192  of the operator platform  190  receives the rear wheel  150 . The operator platform  190  comprises a first side portion  193 , a second side portion  195  and a central portion  197 . The cut-out portion  192  in such cases is surrounded on opposite lateral sides by the first and second side portions  193  and  195 . The first and second side portions  193  and  195  are each integrally formed with the central portion  197 . As seen in  FIG. 5 , the first and second side portions  193 ,  195  extend on opposite sides of the rear wheel  150 . An operator can stand in a standing position such that the first and second side portions  193 ,  195  each receive an operator&#39;s foot. Accordingly, the first and second side portions  193 ,  195  can have a width sufficient to accommodate an operator&#39;s foot,  201 ,  203 . For example, the width can be between about 5 inches and about 8 inches such that an adult operator can comfortably stand in the first and second side portions  193 ,  195  so that the operator&#39;s foot  201 ,  203  are on both sides of the rotational axis  151  (and positioned thereabove). Alternatively, the operator platform  190  may not have a cut-out portion, and can be positioned above the rear wheel  150 . 
     Optionally, in some embodiments wherein the operator platform  190  has a cut-out portion  192 , a cover (not shown) can be positioned over the rear wheel  150  to avoid the operator&#39;s foot from inadvertently contacting the rear wheel  150 . The rear wheel  150  is approximately at the same height above the surface  120  as a central rotational axis of the rear wheel  150 . Such embodiments allow the operator a wider tread surface than is conventionally used in “micro” rider style surface maintenance machine  100  by having the rear wheel  150  be positioned centrally, and by having the operator platform  190  extend around it. In some such cases, the operator platform  190  is of a width  191  that approximately equals the width  139  of the maintenance path  137  and/or the width  136  of the machine. 
     In embodiments illustrated in  FIG. 5 , during a turn (e.g., a zero turn), the point about which the machine turns (referred to as “center of turn”) can generally be within an envelope of the operator platform when the machine is being turned up to and during a zero turn. Such embodiments allow the operator comfort during a turn and further ensure stability during zero turns. 
       FIG. 6  illustrates a side perspective view of a cross-section taken along the plane  6 - 6  illustrated in  FIG. 5 .  FIG. 7  illustrates a top view of a rear portion of the machine  100 . In  FIGS. 6 and 7 , the forward direction of travel of the machine  100  is illustrated by the arrow referenced as  148 . As shown in  FIGS. 6 and 7 , machine  100  has at least one rear wheel  150 . In embodiments where the rear wheel  150  is rotatable, the rotation is about the rotational axis  198 . As seen in  FIGS. 6 and 7 , the operator platform  190  extends both to the front and the rear of the rotational axis  198  of the rear wheel  150 . The central portion  197  is to the rear of the rotational axis  198  and the first and second side portions  193 ,  195  extend to the front and rear of the rotational axis  198 . In such embodiments, when an operator stands on the operator platform  190 , the operator&#39;s feet  201 ,  203  can be to the front and rear of the rotational axis  198 . As is seen in  FIGS. 6 and 7 , the operator platform  190  also extends to the front and rear of the entire rear wheel  150 . The rear wheel  150  is surrounded by the first and second side portions  193 ,  195  and the central portion  197  of the operator platform  190 . The rear wheel  150  can thus be positioned, such that the operator platform  190  extends deeper relative to the diameter of the rear wheel  150 . 
     Embodiments of a surface maintenance machine  100  with a rear operator platform  190  disclosed herein offer several advantages. The rear standing platform allows the operator to standing in a desired position with a wider tread surface than is conventional. The rear standing platform with a wider tread allows the operator to step on and off the machine  100 . Components of the machine  100  according some embodiments are arranged to have the machine  100  be front loaded and the center of gravity  162  be lower toward the ground. Such embodiments offer improved stability, and additionally provide for efficient use of space for packaging batteries and cleaning components. Embodiments also provide for a short overall length for the machine  100 , forward protection for the operator, low step-on height, and easy presentation of controls to the operator. Embodiments of the machine also allows an operator to rapidly decelerate during a turn, thereby providing a safe operation of the machine (e.g., if an operator encounters an obstacle) and results in satisfactory maintenance performance (e.g., by reducing the chances of scrubbing tools from throwing off liquids when turning too fast). 
     Referring now to  FIG. 8 , which illustrates a portion of the machine  100  shown in  FIG. 1B , the surface maintenance machine  100  includes a maintenance head assembly  400 . The maintenance head assembly  400  houses one or more maintenance tools  406  such as scrub brushes, sweeping brushes, and polishing, stripping or burnishing pads, and tools for extracting (e.g., dry or wet vacuum tools) as described previously. The maintenance head assembly  400  comprises a deck  402  that houses one or more maintenance tools  406  (best seen in  FIG. 9 ). The maintenance tool  406  can be rotatable relative to the remainder of the maintenance head assembly  400  (such as the deck  402 ), for instance, by a motive source  404  (e.g., a motor) that can be coupled to the maintenance tool  406  (e.g., using belts, or other motive force transmission systems, not shown) that apply torque and thereby impart a rotational motion on to the maintenance tools  406 . The maintenance head assembly  400  can be attached to the body (e.g., a frame member  104 ) of the surface maintenance machine  100  such that the maintenance head assembly  400  can be lowered to an operating position (so as to be in contact with the floor surface  120 ) and raised to a traveling position when the machine  100  is not performing a maintenance operation. The maintenance head assembly  400  is connected to the surface maintenance machine  100  using any known mechanism, such as a lift mechanism and suspension  452 , as illustrated in U.S. Pat. No. 9,124,544, assigned to the assignee of the present application, Tennant Company of Minneapolis, Minn., the disclosure of which is hereby incorporated by reference. 
     With continued reference to  FIG. 8 , the lift mechanism and suspension  452  allows the maintenance head assembly  400  to be raised and lowered and allows the maintenance tools  406  to conform to undulations in the floor. The deck  402  of the maintenance head assembly  400  is attached to the frame  104  of the machine  100  (not shown in  FIG. 8 ) by a lift mechanism and suspension  452  assembly that includes a lift arm  454 , a linear actuator (not shown), and associated coupling structures. Coupling structures include brackets, springs, control arms, and the like for providing controlled pivoting of the linear actuator relative to the deck  402  so as to remain in contact with the floor surface  120  (e.g., when traveling over uneven floor surfaces) when performing a maintenance operation, and be raised to the traveling position when the machine  100  is not performing a maintenance operation. 
     Components of the lift mechanism and suspension  452  can be operatively coupled to the operator console  126  and/or foot pedals  122  on the operator platform  190 . For example, the foot pedals  122  can be mechanically coupled to coupling structures of the lift mechanism and suspension  452 . Additionally, the foot pedals  122  can be electrically coupled to a controller in communication with the linear actuator such that when the foot pedals  122  are pressed by the operator&#39;s feet, the controller communicates with the linear actuator to raise or lower the maintenance bead assembly to move it between the operating position and the transport position. 
     With continued reference to  FIG. 8 , a squeegee assembly  500  is provided on the rear of and connected to the maintenance head assembly  400 . The squeegee assembly  500  can drag on the surface along the sides of maintenance tool  406  to keep water on the floor from spreading out sidewise away from the machine  100 . The squeegee assembly  500  curves inward to direct the water centrally to the machine  100  toward the rear thereof. A vacuum system (not shown) is fluidly coupled to the squeegee assembly  500  so as to collect the water accumulating on the rear of the machine and deposit the collected water into a waste recovery tank (not shown). The maintenance head assembly  400  can be configured to “float” relative to machine  100 , thereby keeping the maintenance tool  406  (e.g., a brush or a pad) in contact with the surface being maintained (e.g., cleaned or treated) even if the surface is somewhat irregular or uneven. Likewise, due to the mechanical connection between the squeegee assembly  500  and the maintenance head assembly  400 , the squeegee assembly  500  can also float relative to machine  100  to enable the squeegee assembly  500  to remain in contact with surfaces being maintained, even though they are somewhat irregular or uneven. 
     The squeegee assembly  500  includes a frame  502 , squeegee blades  504 ,  506 , and a retainer  508 . Blades may include one or more flexible blades that may be spaced apart or tight against each other. For instance, the illustrated embodiment provides an inner squeegee blade  504  facing the maintenance head assembly  400 , and an outer squeegee blade  506  positioned to the rear of the inner squeegee blade  504  (e.g., when the machine is moving in a generally forward direction). The inner squeegee blade  504  generally confronts water on the floor surface  120  first and directs water toward a central portion of the squeegee blades  504 ,  506 . Further, the inner squeegee blade  504  and outer squeegee blade  506  may be in contact with the floor surface  120 . In some such cases, the inner squeegee blade  504  can have vents to draw-in liquids into a plenum formed by the inner squeegee blade  504  and outer squeegee blade  506 . The squeegee blades  504 ,  506  can therefore form a seal with the floor. The vacuum system may apply a vacuum in the plenum between the outer and inner squeegee blades  504 ,  506 , which, due to the seal formed with the floor surface  120 , and optionally due to vents on the inner squeegee blade  504 , facilitates suction of collected water from the center of the squeegee. Squeegee blades  504 ,  506  can also deflect in a controlled manner to a predetermined extent (for instance, deflection about twice the thickness of the blade) to effectively collect liquids from the floor surface. 
     The blades can contact the floor surface  120  and are made from suitable material such as rubber, neoprene, urethane, or the like. The one or more flexible blades may be of the same or of differing thicknesses, have differing levels of flexibility, and may have differing lower extents. Exemplary squeegee assemblies contemplated in the present disclosure include the squeegee assemblies described in U.S. Pat. No. 9,049,975, assigned to the assignee of the present application, the disclosure of which is hereby incorporated by reference. The squeegee assembly  500  can be of a sufficient weight so as to apply uniform pressure on the squeegee blades  504 ,  506  substantially around the perimeter of the squeegee assembly  500 . For instance, the weight of the squeegee assembly  500  can be configured so as to apply a certain magnitude of downforce on the squeegee blades  504 ,  506 . Additional mechanical members (e.g., wheels and castors, as will be described further below) can further facilitate uniform application of downforce on the squeegee assembly  500 . 
     As described further below, embodiments of the present disclosure permit an interchangeable squeegee assembly  500  that can be connected to different sizes of maintenance tools  406  (brushes or pads), while facilitating easy removal for servicing (e.g., replacing or “rotating” squeegee blades  504 ,  506  due to wear). Further, the squeegee assembly  500  according to certain embodiments of the present disclosure can also be designed as articulating, so as to effectively direct and collect water from the surface when the machine is being turned (e.g., around a corner in a building). 
       FIG. 9  is a top plan view of the assembly shown in  FIG. 8  to illustrate the relative position of the squeegee assembly  500  and the maintenance head assembly  400  when the machine is traveling in a generally straight path in a direction indicated by the arrow.  FIGS. 10 and 11  show respectively, a perspective view and a top plan view of the squeegee assembly  500  of  FIGS. 8 and 9  to illustrate the relative position of the squeegee assembly  500  and the maintenance head assembly  400  when the machine takes a turn relative to the direction  510 . As seen in  FIGS. 8-11 , some embodiments of the present disclosure advantageously provide an articulating mechanism  520  to permit controlled articulation of the squeegee assembly  500  when the machine is turned (e.g., a right or a left turn, relative to the travel direction shown in  FIG. 8 ) to direct and collect water that may pool up when the machine is turned. 
     Referring now to  FIG. 8 , the articulating mechanism  520  is attached to coupling structures on the deck  402  of the maintenance head assembly  400 . For example, the articulating mechanism  520  can be connected to brackets  522  to which the lift arm  454  of the lift mechanism and suspension  452 . Of course, the articulating mechanism  520  can also be connected at other locations on the deck  402  of the maintenance head assembly  400 . The connection of the articulating mechanism  520  can be such that it is easily removable in the event that the squeegee assembly  500  needs to be replaced for servicing. For instance, the connection of the articulating mechanism  520  can be to the exterior of the motive source  404  (e.g., motor) of the maintenance head assembly  400 , so that an operator may be able to detach the squeegee assembly  500  without having to disconnect numerous connections such as those of the lift mechanism and suspension  452 , and the like. 
     As seen in  FIGS. 10 and 11 , the articulating mechanism  520  permits controlled articulation of the squeegee assembly  500 . As used herein, the term articulation may include both pivotal motion (along arrows  524 ) of the squeegee assembly  500  relative to the maintenance head assembly  400  about a pivot axis  526 , as well as swivel motion (along arrows  528 ) of the squeegee assembly  500  about the swivel axis  530 . In some exemplary embodiments, the articulating mechanism  520  may permit a swivel of about 80 degrees either side of the swivel axis  530 , thereby a total swivel arc of about 170 degrees. Such embodiments permit effectively collecting water from behind the machine when the machine completes a sharp turn of about 90 degrees. In such cases, as is apparent to one skilled in the art, the swivel axis  530  of the squeegee assembly  500  generally coincides with the center of turn of the machine and/or centroid of the maintenance head assembly  400 . 
       FIGS. 12 and 13  illustrate another embodiment of the maintenance head assembly  600 . The maintenance head assembly  600  of  FIGS. 12 and 13  are substantially similar to that illustrated in  FIGS. 8 and 9 , with the exception that the embodiment of  FIGS. 12 and 13  is generally oval in shape (as seen from the top plan view of  FIG. 13 ), with a deck  602  configured to house a pair of disc-shaped maintenance tools (e.g., brushes or pads), whereas the embodiment of  FIGS. 8 and 9  is generally circular in shape (as seen from the top plan view of  FIG. 9 ). In the view shown in  FIGS. 12 and 13 , the machine is traveling in a generally straight path, in a direction indicated by the arrow  606 .  FIGS. 14 and 15  show respectively, a perspective view and a top plan view of the maintenance head assembly  600  of  FIGS. 12 and 13  to illustrate the relative position of the squeegee assembly  500  and the maintenance head assembly  600  when the machine takes a turn. While the articulating mechanism  520  is described above with respect to  FIGS. 8-11 , it should be understood that the articulating mechanism  520  shown in  FIGS. 12-15  operates in a similar fashion to that shown in  FIGS. 8-11 . 
       FIG. 16  illustrates an enlarged perspective view of the articulating mechanism  520 . The articulating mechanism  520  seen in  FIG. 16  can be coupled to the maintenance head assembly  400  shown in  FIGS. 8-11  or maintenance head assembly  600  shown in  FIGS. 12-15 . As seen therein, the articulating mechanism  520  comprises a swivel mechanism  610  for controlled swivel of the squeegee assembly  500  about the swivel axis  530  and a hinge mechanism  630  for controlled pivoting of the squeegee assembly  500  about the pivot axis. The swivel mechanism  610  comprises at least one curved rail on which two or more rollers  616 ,  618  are guided. In the illustrated embodiment, two curved rails  612 ,  614  radially offset from each other. The rails  612 ,  614  are curved such that they have a center of curvature that coincides with the swivel axis  530 , and in turn, the center of turn of the machine and/or centroid of the maintenance head assembly  400 . In the illustrated embodiment, the curvature of the rails  612 ,  614  corresponds to an arc extending between about 130 degrees and about 180 degrees. Further, the curvature of the rails  612 ,  614  is generally circular (e.g., as seen from the top view of  FIGS. 9, 5, 7 and 9 ) such that any two points on the rails  612 ,  614  are generally equidistant from the center of the curvature of the rails  612 ,  614  (as is apparent from  FIGS. 12-15 ). While two rails having a fixed radius corresponding to a circular shape is illustrated, other shapes of the rails  612 ,  614  (e.g., a non-circular curvature) can be used to customize the articulating mechanism based on the machine architecture. For example, the rails  612 ,  614  can follow a generally oval shape when viewed from the top so as to conform to the shape of the oval maintenance head assembly shown in  FIG. 12-9 . Alternatively, a non-uniform shape can also be used for other machine and/or maintenance head assembly architectures. 
     While the rails  612 ,  614  are illustrated as being generally tubular in shape, other shapes such as rectangular or square cross-section are contemplated within the scope of the present disclosure. Further, in addition to being radially offset, the rails  612 ,  614  can be axially offset (e.g., along the swivel axis  530 ) such that one rail is above another rail. Alternatively, the rails  612 ,  614  may not be radially offset, but may be axially offset such that one rail is above another rail, but both rails have the same radius from their center of curvature. Any orientation of the rails  612 ,  614  that is adequately rigid and resists structural loads (e.g., flexures) generated due to swiveling of the squeegee assembly  500  when the machine turns, and supports the weight of the squeegee assembly  500  can be used. Additionally, while rails are illustrated, it should be noted that track and carriage systems or other mechanical equivalents that permit guided motion of the squeegee assembly  500  over an arcuate path are contemplated within the scope of the present disclosure. 
     With continued reference to  FIG. 16 , the swivel mechanism  610  comprises a pair of rollers  616 ,  618  housed in a swivel bracket  620  that roll against the rails  612 ,  614 . The rollers  616 ,  618  and rails  612 ,  614  can be configured to have minimal friction therebetween such that the rollers  616 ,  618  freely roll in a guided fashion along the rails  612 ,  614 . For instance, and referring now to the sectional view of  FIG. 17 , the rollers  616 ,  618  comprise an outer sleeve  622  made of low-friction materials such as Delrin, nylon, and the like permitting frictionless rolling motion of the outer sleeve  622  on at least one rail (for instance, the inner rail  612 ). Additionally, the rollers  616 ,  618  can also roll on the outer rail  614 . Further, the rollers  616 ,  618  comprise a metal bushing  624  housed within the outer sleeve  622  so that the rollers  616 ,  618  can maintain structural rigidity and withstand dynamic loads experienced while rolling on the rails. For example, while the outer sleeve  622  may roll against at least one of the rails  612 ,  614  when the machine turns, the bushing  624  may be substantially stationary relative to the outer sleeve  622  so as to support and balance the articulating motion of the squeegee assembly  500  and associated loads acting thereon. The outer sleeve  622  of the rollers  616 ,  618  can have end caps that engage with at least one of the rails  612 ,  614 , and to reduce the chances of the rollers  616 ,  618  separating from the rails  612 ,  614 . In the illustrated embodiment, the rollers  616 ,  618  are shaped to resemble spools, although any shape that provides the above-described function is contemplated within the scope of the present disclosure. 
     Referring back to  FIG. 16 , the rollers  616 ,  618  are connected to the swivel bracket  620  by way of a bolted connection. When connected, the rollers  616 ,  618  are spaced apart from each other along a circumferential direction by an arc distance. In the illustrated embodiment, the spacing between the two rollers  616 ,  618  extends an arc of between about 15 degrees and about 30 degrees. Such embodiments provide sufficient resistance to certain forces by spreading out such forces acting on the swivel mechanism  610  over a larger area. For instance, if the squeegee assembly  500  abuts against an obstacle and experiences side impact when the squeegee assembly  500  has swiveled to the position shown in  FIGS. 10-11  or  FIGS. 14-15 , the side impact experienced by the squeegee assembly  500  is spread out over a substantial area of the swivel bracket  620 , thereby reducing damage to the swivel mechanism  610 . As is apparent to one skilled in the art, further spacing the rollers  616 ,  618  apart may provide additional area to distribute impact loads, however, at the expense of reduced swivel path. While the examples illustrated herein permit a swivel of about 80 degrees on either side of the swivel axis  530  (for a total of about 170 degrees), larger or smaller swivel is contemplated within the scope of the present disclosure. For example, the swivel can be between about 100 degrees and about 270 degrees. Similarly, roller spacing greater than or less than those illustrated (e.g., between about 15 degrees and about 30 degrees) are contemplated within the scope of the present disclosure. 
     Referring back to  FIG. 8 , as alluded to before, the rails  612 ,  614  are connected to the maintenance head assembly  400  by way of brackets  522  and a bolted connection. Advantageously, the brackets  522  connect to the brackets of the lift mechanism and suspension  452  which provides a compact connection of the squeegee assembly  500  to the maintenance head assembly  400 . The brackets, while illustrated as L-shaped, can be of any shape so as to serve as limit stops for the swivel mechanism  610  to reduce the chances of the squeegee assembly  500  traveling too far, and being damaged (e.g., by making contact with wheels  140  of the machine). In the illustrated embodiment, the brackets are positioned diametrically opposite to each other (e.g., about 180 degrees apart) accommodate a swivel arc of between about 100 degrees about 180 degrees, though of course, the brackets  522  may be positioned closer or farther apart. 
     Referring again to  FIG. 16 , the articulating mechanism  520  comprises a hinge mechanism  630  for controlled pivoting of the squeegee assembly  500  relative to the maintenance head assembly  400  about one or more pivot axes. The hinge mechanism  630  facilitates maintaining the squeegee assembly  500  (e.g., squeegee blades  504 ,  506 ) generally parallel to the floor. The hinge mechanism  630  permits the squeegee blades  504 ,  506  (e.g., the outer squeegee blade  506 ) to remain in contact with the floor surface  120 . The hinge mechanism  630  is a double-hinge design, permitting pivoting of the squeegee assembly  500  relative to the maintenance head assembly  400  about a first pivot axis  526 , and a second pivot axis  632 . The first pivot axis  526  offset vertically above the second pivot axis  632 . The hinge mechanism  630  comprises a hinge plate  634  that engages with the swivel bracket  620  at one end, and an H-shaped hinge bracket  636  at the other end. The first pivot axis  526  passes through the hinge plate  634 . The hinge bracket, in turn is connected with vertical brackets  638  by a bolted connection. The second hinge axis passes through the bolted connection between the hinge bracket and the vertical brackets  638 . 
     Such a configuration may permit the squeegee to be in contact with the floor surface  120  in different modes. For instance, the machine may be operated when the squeegee picks up water from floor while the maintenance tool  406  (e.g., scrub brush) is in contact with the floor surface  120  and is performing a maintenance operation (e.g., scrubbing). Alternatively, the machine may be operated such that the squeegee picks up water from the floor while the maintenance tool  406  is not in contact with the floor surface  120 , for instance, when excess water from a flooding may have to be picked up from the ground. Still further, the squeegee may have to not be in contact with the floor surface  120  while the maintenance tool  406  is performing a maintenance operation (e.g., a pre-soak while scrubbing). In such cases, the double hinge design of the hinge mechanism  630  allows the squeegee assembly  500  to be raised above or below the maintenance head assembly  400 , while also permitting the squeegee blades  504 ,  506  to be parallel to the floor surface  120 . Such embodiments advantageously offer effective water pick-up which may not be possible with hinge mechanism  630  that permit pivoting about a single pivot axis. Instead of the illustrated hinge mechanism  630 , mechanical equivalents, such as a vertically-oriented slot and/or rollers housed within the vertical slot can also be used in alternative embodiments. 
       FIG. 18  illustrates a side view of the squeegee assembly  500  of the present embodiment. As mentioned above, the embodiment illustrated in  FIG. 18  can be used interchangeably with the maintenance head assembly  400  shown in  FIGS. 8-11  or  FIGS. 12-15 . The squeegee assembly  500  comprises a first set of end wheels. In the illustrated embodiment, the squeegee assembly  500  comprises four end wheels. A first end wheel  642  is configured to roll on the surface  120  when the squeegee assembly  500  articulates (e.g., into the positions shown in  FIGS. 10, 11, 14 and 15 ) when the machine turns. Further, a second end wheel  644  provided with a rotational axis  646  perpendicular to the rotational axis  648  of the first end wheel  642 . Further, the first end wheel  642  may swivel about the plane containing the rotational axis  646 , for instance, relative to the maintenance head assembly as illustrated in  FIG. 18 . As is apparent to one skilled in the art, the squeegee assembly  500  comprises a second set of end wheels opposite to the first set of end wheels so that the first and second set of end wheels terminate at the opposite ends of the curved squeegee assembly  500 . Similar to the first set of end wheels, the second set of end wheels may comprise a third end wheel  650  configured to roll on the surface  120  when the squeegee assembly  500  articulates (e.g., into the positions shown in  FIGS. 10, 11, 14 and 15 ) when the machine turns. Further, a fourth end wheel  652  provided with a rotational axis perpendicular to the rotational axis of the third end wheel  650 . While end wheels are illustrated as cylindrical members that can swivel, it should be understood that castors may also be used in lieu of end wheels without loss of functionality. In the illustrated embodiment, end wheel  652  may act as a bumper when the squeegee assembly encounters lateral impacts due to an obstruction (e.g., a wall), whereas the end wheel  644  can support the front of the squeegee assembly during transport. Instead of wheels  644  and/or  652 , as is apparent to one skilled in the art, other mechanical means that act as bumpers and/or supports (e.g., simple brackets) may be used without loss of functionality. 
     In addition to the set of end wheels, as is seen from  FIG. 18 , the squeegee assembly  500  includes a caster  660  positioned centrally between the first and second set of end wheels. As indicated previously, the mass of the squeegee assembly  500  facilitates applying a predetermined magnitude of downforce on the squeegee blades  504 ,  506 . The end wheels (e.g., first end wheel and third end wheel  650 ) and caster  660  can further facilitate uniform application of downforce on the squeegee assembly  500 . 
     The caster  660  and/or end wheels may also facilitate articulating the squeegee assembly  500  corresponding to the direction of turn of the machine. For instance, when the machine turns in a certain predefined direction (e.g., a 90-degree right turn relative to its forward direction of motion), as a result of the frictional contact of the squeegee blades  504 ,  506  on the floor surface  120  and the squeegee assembly  500  may articulate to follow the direction of turn of the machine, while collecting water from rearward of the machine. For example, to collect water as the machine turns, the squeegee may articulate in a direction opposite to the direction of turn of the machine (e.g., as a result of frictional contact of the squeegee blades  504 ,  506  with the floor surface). Thus, if the machine makes a 90 degree turn relative to the forward direction, the squeegee assembly  500  may move leftward relative to the forward direction. Such a motion of the squeegee assembly  500  may be cooperatively accomplished by the uniform downforce acting on the squeegee blades  504 ,  506 , and/or vacuum between the squeegee blades  504 ,  506 , which acts to keep the squeegee blades  504 ,  506  pressed against the floor surface  120  while the machine turns, and/or the motion of the caster  660  and/or end wheels. 
     Embodiments of the present disclosure provide an interchangeable squeegee assembly that can articulate when the machine turns to effectively pick up water during wet maintenance operations such as scrubbing. The articulating mechanism according to the present disclosure may be interchangeably used with maintenance tools (e.g., scrub brushes) of different size, and may attach to exterior components of maintenance head assemblies to permit easy removal for servicing and/or replacement. 
       FIGS. 19-22  illustrate portions of the surface maintenance machine with several of the external body panels not shown in  FIGS. 1-5 . As illustrated, the body panels, when added, define a storage area for storing a variety of tools and supplies  740  as will be described further below. With reference to  FIG. 19 , the mobile body of the surface maintenance machine includes a forward section  700 , a middle section  702  and a rearward section  704 . The terms “forward”, “rearward” and “middle section  702 ” are referenced with respect to the direction of travel  148  of the machine and the transverse centerline  146  of the machine. For instance, as illustrated, the forward section  700  is positioned to the front of the transverse centerline  146  of the machine, the middle section  702  is generally centered on the transverse centerline  146  and the rearward section  704  is positioned to the rear of the transverse centerline  146 , when the machine moves in the direction  148 . 
     With continued reference to  FIG. 19 , and referring now to  FIG. 20 , the forward section  700  extends over a forward section depth  700   d , the middle section  702  extends over a middle section depth  702   d , and the rearward section  704  extends over a rearward section depth  704   d . As is apparent, each of the forward section depth  700   d , the middle section depth  702   d , and the rearward section depth  704   d  can be defined in a direction parallel to the direction of travel  148  of the machine. Further, the forward section  700  can extend over a forward section width  700   w , the middle section  702  extends over a middle section width  702   w , and the rearward section  704  extends over a rearward section width  704   w . In this case, each of the forward section width  700   w , middle section width  702   w  and the rearward section width  704   w  can be defined in a direction perpendicular to the direction of travel  148  and/or between lateral walls  116 ,  118  of the machine. 
     The machine can have overall dimensions configured such that at least two of the forward section depth  700   d , the middle section depth  702   d , and the rearward section depth  704   d  are equal. Further, at least two of the forward section width  700   w , the middle section width  702   w , and the rearward section width  704   w  can be equal. In some examples, the forward section  700  and the rearward section  704  can have generally equal dimensions. Further, the forward section  700 , the middle section  702  and the rearward section  704  can all be substantially of the same dimensions. 
     With reference to  FIG. 20  and referring now to  FIG. 21 , body panels of the machine may define the boundaries of the storage area so as to isolate it from various components of the machine such as batteries  744 , solution and/or recovery tanks, sweep chamber and/or hopper, maintenance tools, and the like. For instance, the body may have a center plane  166  parallel to the floor surface and a generally planar top surface  710  positioned above the center plane  166  of the body and generally parallel thereto. The generally planar top surface  710  can be at a first distance  712  above the floor surface. Further, the body can have a generally planar lower surface  714  positioned below the center plane  166  of the body and generally parallel thereto. The generally planar lower surface  714  can be located at a second distance  720  below the generally planar top surface  710 . 
     With continued reference to  FIGS. 20 and 21 , the body panels may further include boundaries that define a storage chamber  730 . For instance, the body panels may include a front wall  732 , a rear wall  734 , lateral walls  736 ,  738 , such that the storage chamber  730  is generally isolated from components of the surface maintenance machine and generally hollow to permit storage of maintenance tools and/or supplies  740 . As mentioned previously, “front”, “rear” and “lateral” refer to the position and orientation with respect to the direction of travel  148  and/or transverse centerline  146 . As seen in  FIGS. 20 and 21 , the front wall  732  of the storage chamber  730  abuts the forward section  700  and the rear wall  734  of the storage chamber  730  abuts the rearward section  704 . For instance, the front wall  732  can be a common boundary between the forward section  700  and the middle section  702 . Likewise, the rear wall  734  can be a common boundary between the middle section  702  and rearward section  704 . As seen in  FIGS. 20 and 21 , the storage chamber  730  extends over a depth  730   d  (defined between its lateral walls  736 ,  738 ) substantially equal to the middle section depth  702   d  and over a width  730   w  substantially equal to the middle section width  702   w.    
     Referring back to  FIG. 20 , the generally planar top surface  710  can be located at a first distance  712  from the floor surface whereby, the first distance  712  corresponds to the machine height. In such cases, the storage chamber  730  can extend between the generally planar top surface  710  and the generally planar lower surface  714  of the machine body wherein the generally planar lower surface  714  is at a second distance  720  below the generally planar top surface  710 , such that the second distance  720  generally corresponds to the height of the storage chamber  730 . In some such cases, the second distance  720  is greater than about two-thirds of the first distance  712 . In such cases, the storage chamber  730  may extend over a height of about two-thirds the height of the machine. 
     Referring again to  FIG. 21 , the boundaries of the storage chamber  730  facilitate substantially isolating the storage chamber  730  from components of the machine. For instance, the storage chamber  730  can be fluidly isolated from a maintenance chamber  742  that houses one or more maintenance tools. Further, as seen in  FIG. 21 , components of the machine can be re-arranged so as to permit a substantially hollow middle section  702  for defining the storage chamber  730 . For instance, components of the machine such as batteries  744  for propelling the machine, and/or recovery tank  746  for collecting fluids from the floor surface, can be substantially located in the forward section  700 . Further, solution tank for supplying a fluid toward a floor surface may be positioned outside the middle section  702 . In the illustrated embodiment, for instance, the solution tank is defined peripherally around the body of the vehicle, with an inlet port  748  positioned in the rearward section  704 . 
     With continued reference to  FIG. 21 , and as indicated above, components of the machine (e.g., such as batteries  744 , maintenance head assemblies, solution tanks, vacuum systems, machine controls and the like), can be arranged to create a substantially hollow portion having a volume sufficient to house the storage chamber  730 . As shown in  FIG. 21 , in one example, the entirety of the batteries  744  and the recovery tank  746  can be respectively located in the forward section  700 , though, portions of the recovery hose  749  may pass around the storage chamber  730 . Continuing with the example illustrated in  FIG. 21 , a storage chamber bottom surface  747  can be coplanar with or below a top surface  751  of at least one battery positioned in the forward section  700 . Such embodiments permit an adequate volume of storage chamber  730  to store a variety of maintenance tools and/or supplies  740 . 
     Referring now to  FIG. 22 , the storage chamber  730  comprises one or more access doors for permitting access to the storage chamber  730  when opened. In the illustrated embodiment, the storage chamber  730  comprises a first access door  750  configured to open in a lateral direction  752 . The first access door  750  can be formed by at least portions of a lateral wall of the storage chamber  730 . Further, the first access door  750  (and in turn, the lateral walls  736 ,  738  of the storage chamber  730 ) can be generally coplanar with lateral walls  116 ,  118  of the machine, such that the storage chamber  730  is generally confined within the lateral extents of the machine and does not protrude outside of the machine envelope. With continued reference to  FIG. 22 , the storage chamber  730  comprises a second access door  754  configured to open in a direction  756  perpendicular to the direction of opening  752  of the first access door  750 . Additionally, either, or both of the first access door  750  and the second access door  754  may be accessible from the operator platform such that the operator may access them (e.g., grasp and/or open). As is apparent from  FIGS. 19-22 , the second access door  754  is generally coplanar with the generally planar top surface  710  such that the storage chamber  730  can remain confined within a machine envelope. In such cases, the lateral walls  116 ,  118  of the machine and the generally planar top surface  710  may constitute at least portions of the outer boundaries of the envelope. 
     Referring back to  FIG. 19 , the storage chamber  730  defined in the middle section  702  of the machine body for storing surface maintenance tools and supplies  740  that an operator may use for performing one or more manual surface maintenance tasks. For instance, the operator may remove the surface maintenance tools and/or supplies  740 , such as spray bottles housed in a caddy  800  with a one or more bins  804 , brooms and/or mops  806 , wash cloths, and the like and transport them manually to a location where a manual maintenance operation is to be performed. Referring now to  FIG. 21 , the storage chamber  730  may also be configured to store debris collected from the manual maintenance, for instance, in a trash bag  810 , that may be positioned in the storage chamber  730  (e.g., using frame elements  812 ). 
     As seen in  FIG. 22  and referring to the enlarged portions thereof illustrated in  FIGS. 23A-23C , the storage chamber  730  can be of a modular design so as to facilitate housing individual storage modules such as a storage caddy  800 , one or more storage bins  804 , a drip catching bin for storing/collecting fluids from a mop, a debris compartment and the like. For instance, in  FIG. 23A , the storage chamber  730  is illustrated as having a trash bag  810  housed therewithin, whereby the trash bag  810  extends substantially over the height of the storage chamber  730 .  FIG. 23B  illustrates another use of the storage chamber  730 , whereby the trash bag  810  extends over one half of the height of the storage chamber  730 , and a storage bin is placed in the remaining space.  FIG. 23C  illustrates a further use of the storage chamber  730 , wherein a plurality of bins  804 /trays can be placed in the space within the storage chamber  730  instead of a trash bag  810 . Any such modular arrangements are contemplated within the scope of the present disclosure. 
     Embodiments of the surface maintenance machine with storage areas such as those illustrated herein permit an operator to store tools and supplies  740  for performing manual surface maintenance operations in situations where the machine may not be able to travel (e.g., areas with aisle widths narrower than the width of the machine) for collecting large dry debris or for off-the-floor manual maintenance. 
     Various examples have been described. These and other examples are within the scope of this disclosure.