Abstract:
A floor tool for use in vacuum cleaning floor surfaces includes a sole plate for engaging with a floor surface, a supporting body for the sole plate having means such as wheels or rollers for allowing the body to ride along the floor surface and an outlet conduit for coupling to a wand of a vacuum cleaner. The outlet conduit is mounted to the support platform by a connecting arm, a first end of the connecting arm being pivotally connected to the outlet conduit about a first axis and the second end of the connecting arm being pivotally connected to the supporting body about a second axis. The first and second axes are substantially parallel to one another. Fluid flow from the sole plate can be carried by a flexible hose or by the connecting arm itself.

Description:
REFERENCE TO RELATED APPLICATIONS 
   This application is the national stage under 35 USC 271 of International Application No. PCT/GB02/04834, filed Oct. 25, 2002, which claims the priority of United Kingdom Application Nos. 0126494.4 and 020692.3, filed Nov. 3, 2001, and Apr. 27, 2002, respectively, the entire contents of which are incorporated herein by reference. 
   FIELD OF THE INVENTION 
   This invention relates to a floor tool for use with a vacuum cleaner. 
   BACKGROUND OF THE INVENTION 
   Cylinder or canister vacuum cleaners, as shown in  FIG. 1 , generally comprise a main body  10  which contains separating apparatus  11  such as a cyclonic separator or a bag for separating dirt and dust from an incoming dirty airflow. The dirty airflow is introduced to the main body  10  via a hose  15  and wand  16  assembly which is connected to the main body  10 . The main body  10  of the cleaner is dragged along by the hose as a user moves around a room. A cleaning tool is attached to the remote end of the hose and wand assembly. A range of cleaning tools are usually supplied so that a user can choose an appropriate tool for their cleaning task, such as a crevice tool and a brush tool. For general on-the-floor cleaning the vacuum cleaner is provided with a floor tool  20 . 
     FIG. 2  shows a known floor tool of the type manufactured and sold by Dyson Limited. The floor tool  20  comprises a lower face  150 , commonly known as a sole plate, which engages with a floor surface. The sole plate  150  defines a suction channel  155  which faces the floor surface and serves, in use, to expose the floor surface to a suction force which is sufficient to carry dirt and debris from the surface. The tool  20  also comprises an outlet connector  101 ,  102  which fits to the wand  16  ( FIG. 1 ) and a short connecting duct  120  for carrying airflow from the sole plate  150  to the outlet connector  101 ,  102 . One end of the connecting duct  120  is pivotally mounted to the sole plate about axis  105  and the other end of the connecting duct is pivotally mounted to the outlet connector  101  about axis  115 . The connecting duct  120  has a pair of floor engaging wheels  90  mounted on it. In use, this arrangement translates a user&#39;s pushing and pulling movement of the wand to a gliding movement of the sole plate  150  over the floor surface. However, it has been found that the manner in which some users operate the wand can cause the sole plate  150  of the tool  20  to lift off of the floor surface. This has a detrimental effect on the pick-up performance of the floor tool  20 . 
   SUMMARY OF THE INVENTION 
   Thus, the present invention seeks to provide an improved floor tool. 
   Accordingly, the present invention provides a floor tool for use in vacuum cleaning floor surfaces comprising a sole plate for engaging with a floor surface, a supporting body for the sole plate having means for allowing the body to ride along the floor surface, an outlet conduit for coupling to a wand of a vacuum cleaner, and a connecting arm for connecting the outlet conduit to the supporting body, a first end of the connecting arm being pivotally connected to the outlet conduit about a first pivotal axis, the second end of the connecting arm being pivotally connected to the supporting body about a second pivotal axis, the first and second pivotal axes being substantially parallel to one another, and the connecting arm being pivotable between lowered and raised positions. 
   This has the advantage that the floor tool is less prone to lifting off of a floor surface as a user manipulates the tool. We have found that this improved contact with the floor surface can increase the pick-up performance of the tool. 
   Preferably the sole plate is pivotally mounted to the supporting body and, more preferably, the sole plate is pivotally mounted to the supporting body at a position which lies over a suction channel of the sole plate. The pivotal mounting of the sole plate causes the tool, in use, to rotate forwardly or backwardly. This can be used to bring a working edge of the sole plate into contact with the floor surface so as to agitate the floor surface. In these arrangements it is preferable that the sole plate is pivotally mounted to the supporting body and the connecting arm is pivotally mounted to the supporting body at a position which is substantially coincident with the pivotal axis of the sole plate. 
   The connecting arm can comprise a rigid member which provides mechanical connection between the outlet conduit and the supporting body and the floor tool can further comprise a flexible hose for carrying fluid flow between a suction outlet of the sole plate and the outlet conduit. Alternatively, the connecting arm itself can carry fluid flow between a suction outlet of the sole plate and the outlet conduit. 
   Preferably the floor tool further comprises a skirt for riding along the floor surface during hard floor cleaning, and wherein the sole plate is movable between a working position, in which the sole plate is lower than the skirt and a stored position in which the sole plate is higher than the skirt. 
   Preferably the supporting body of the floor tool has a channel for receiving the connecting arm. The connecting arm can be dimensioned such that, when the connecting arm lies alongside the supporting body, the pivotal connection between the first end of the connecting arm and the outlet conduit lies within the channel on the supporting body. For compactness, wheels or rollers can be mounted on each side of the channel. 
   Preferably the floor tool further comprises stop means for limiting movement of the connecting arm in a direction away from the chassis. Where the supporting body of the floor tool has a channel for receiving the connecting arm, the stop means can act between the connecting arm and at least one side of the channel. 
   The floor tool can be used with cylinder, upright and other types of vacuum cleaning appliances. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Embodiments of the present invention will now be described with reference to the accompanying drawings, in which: 
       FIG. 1  shows a known vacuum cleaner and floor tool in accordance with the prior art; 
       FIG. 2  shows the floor tool of  FIG. 1  in more detail; 
       FIG. 3  shows, in schematic form, a floor tool in accordance with an embodiment of the invention; 
       FIG. 4  shows, in schematic form, an alternative embodiment of the invention; 
       FIG. 5  shows the embodiment of  FIG. 4  in more detail; 
       FIG. 6  shows the tool of  FIG. 5  from the rear; 
       FIG. 7  is a cross section through the floor tool shown in  FIGS. 5 and 6  with the sole plate in a lowered position; 
       FIG. 8  shows the lower face of the floor tool of  FIGS. 5-7 ; 
       FIGS. 9 and 10  are further cross sections through the floor tool of  FIGS. 5-8  with the tool in alternative configurations; 
       FIGS. 11 and 12  show, in schematic form, the action of the sole plate; 
       FIG. 13  shows the forces on a conventional floor tool; 
       FIG. 14  shows the forces on a floor tool in which the push/pull force is applied close to the sole plate; 
       FIG. 15  shows in detail, the passage of debris into the floor tool during a hard floor mode of cleaning operation; 
       FIG. 16  shows a map of the pressures within a floor tool of the type shown in  FIG. 15 ; 
       FIGS. 17A and 17B  show the effect of using the floor tool on a floor surface having a crevice; 
       FIGS. 18-20  show a modification to the floor tool which allows a user to control the flow of air into the floor tool. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 3  shows, in simplified form, the components of a floor tool in accordance with a first embodiment of the invention. The main components of the tool  200  are a main chassis  210 , a sole plate  250 , a wand connector  240  for connecting to a wand or hose of a vacuum cleaner, a connecting arm  230  which connects the chassis  210  to the wand connector  240  and a hose  235  for carrying airflow from the sole plate  250  to the wand connector  240 . The sole plate defines an air inlet  255  which, in use, faces the floor surface and extends transversely across the full width of the tool. The chassis  210  is provided with wheels  221  to allow it to move across a floor surface. The wand connector  240  is dimensioned so as to mate with a wand (i.e. a pipe or a set of telescopic pipes) of a vacuum cleaner. The wand connector  240  is connected to the chassis  210  by a connecting arm  230 . A first end of the connecting arm  230  is pivotally connected to the wand connector  240  by a joint  231 . The other end of the connecting arm  230  is pivotally connected, by joint  232 , to the chassis  210 . Connecting arm  230  provides a mechanical connection between the wand connector  240  and chassis  210  and thus it serves to transmit the force exerted by a user on the wand to the chassis  210 . The connecting arm  230  can be formed as an airflow conduit for carrying airflow from the sole plate  250  to the wand connector  240 . In this case, joints  231 ,  232  are articulated, airtight, joints which maintain an airtight seal between the connecting arm conduit  230  and the outlet of the sole plate  250  and the inlet of the wand connector  240  as these parts move with respect to one another. Alternatively, as is shown in  FIG. 3 , the airflow between the sole plate  250  and wand connector  240  can be carried by a flexible conduit  235  which is separate from the connecting arm  230 . The use of a flexible conduit to carry the airflow allows a more reliable seal to be formed between the wand connector  240  and the connecting arm  230  which will remain airtight over a range of relative positions of the two parts. Thus, this solution can be cheaper and more reliable. 
   The provision of a pivotable joint  231 ,  232  at each end of the connecting arm  230  allows the wand connector  240 , and the wand or hose fitted to the wand connector  240 , to be moved through a wide range of operating positions with respect to the chassis  210 . Furthermore, the chassis  210  and hence the sole plate  250  remain in a stable position throughout the range of operating positions. 
   It is preferable that sole plate  250  is pivotally connected to the chassis  210  and that the axis about which the sole plate  250  pivots is coincident with the axis  232  about which the connecting arm  230  pivots about the chassis  210 . Also, it is preferable for the sole plate to be pivotally connected at a position which lies directly above the centre of the suction channel  255 . The connection between the sole plate  250  and the chassis  110  allows a limited degree of movement between these parts. This is achieved by mounting stops on the chassis  210  at each permitted extent of the path of the sole plate. 
   It is common for a floor tool to be operable in both a carpet cleaning mode, where the sole plate rides along the floor surface, and a hard floor cleaning mode where a flexible skirt of some kind is brought into contact with the floor surface and the sole plate is spaced from the hard floor surface. The tool shown in  FIG. 3  can be provided with a skirt  270  (shown in broken lines) which surrounds the sole plate  250  and which is movable from the raised position shown in  FIG. 3  to a lowered position where it lies beneath the sole plate  250 . 
   An alternative to moving the skirt  270  is for the skirt  270  to remain fixed and to raise or lower the sole plate  250  itself. The tool which is shown in detail in  FIGS. 5-10  has a movable sole plate  250  of this kind. Before describing this tool in detail,  FIG. 4  shows the main components of the tool. Many of the components are the same as for the tool just described with reference to  FIG. 3 . The differences are in the mechanism which links the connecting arm  230  to the chassis  210 . In  FIG. 3  the connecting arm  230  pivots directly about the chassis  210  whereas in  FIG. 4  connecting arm  230  is linked to the chassis  210  via two intermediate arms  234   a ,  234   b . In carpet floor mode the sole plate  250  engages with the floor surface. Sole plate  250  is free to pivot directly about the connecting arm  230 . In hard cleaning mode the sole plate is raised and rotated into a cavity within the chassis  210 . It will be appreciated that the two intermediate arms  234   a ,  234   b  simply link the connecting arm  230  to the chassis  210  in a manner that allows the sole plate  250  to be lowered or raised. In the configuration shown in  FIG. 4  the two intermediate arms  234   a ,  234   b  are locked in position and do not move. Similarly, in the configuration where the sole plate is raised, the intermediate arms are locked in a different position. In both configurations the connecting arm  230  effectively pivots about the chassis  210 . 
   Referring now to  FIGS. 5-10 , these show a preferred embodiment of the floor tool in detail. As before, the main components of the tool  200  are a main chassis  210 , a sole plate  250 , a wand connector  240  for connecting to a wand or hose of a vacuum cleaner and a connecting arm  230  and a hose  235  for connecting the wand connector  240  to the chassis  210 . When viewed from the rear, parallel to the floor, the chassis  210  has a generally unshaped channel which is sufficiently wide to receive the connecting arm  230 . This permits the connecting arm  230 , in use, to lie within the channel, as best shown in  FIG. 6 . The connecting arm may adopt this lowered position during a forward stroke or when a user is maneuvering the tool beneath an obstacle and wants to minimise the height of the tool.  FIG. 6  shows the floor tool from the rear, with the movable parts, i.e. the connecting arm  230  and wand connector  240 , shown with diagonal shading. The connecting arm  230  is shorter than the chassis so that it does not protrude beyond the back of the chassis when the connecting arm is brought to its lowest position. 
   The chassis  210  is provided with wheels  221  which allow the chassis  210  to move across the surface of a floor. A short axle  222  is secured to, and extends outwardly from each side of, a side wall on the rearward part of the chassis  210 . A wheel  221 ,  223  is rotatably secured on each of the axles  222  so as to allow movement of the tool across a floor surface. It will be appreciated that the two short axles  222  could be replaced by a single axle which extends across the full width of the chassis, the wheels could be replaced by rollers, by skids on the lower surface of the tool, or by some other means for allowing the floor tool to move across the surface of a floor. The chassis is provided with means for limiting the vertical movement of the connecting arm  230  beyond a predetermined point. In this embodiment, each side wall at the rear of the chassis  210  is capped by a flange  246  which extends inwardly into the channel and each side of the connecting arm  230  has an outwardly projecting peg  248 . The connecting arm  230  is free to move within a predetermined vertical range. At the uppermost extent of the vertical range the peg  248  on the connecting arm  230  hits, and is arrested by, the flange  246  as is best shown in  FIGS. 9 and 10 . It will be appreciated that this function of limiting the vertical movement of the connecting arm  230  could be achieved in other ways. For example, the side walls can have an inwardly projecting peg which locates within a slot on the connecting arm  230 .  FIG. 10  shows how cushioning material  249 , such as foam padding, can be provided on the base of the chassis at the position beneath where the connecting arm will lie so as to minimise damage and noise when the connecting arm  230  is lowered against the chassis  210 . 
   A wand connector  240  is located at the rear of the tool. The wand connector  240  is dimensioned so as to mate with a wand ( 16 ,  FIG. 1 ) of a vacuum cleaner. The wand connector  240  is formed as two pipes  243 ,  244  which are jointed in a manner which permits rotational movement about the longitudinal axis of the pipes. The wand connector  240  has a castor wheel  245  mounted on its underside so as to minimise damage to a floor surface when the wand connector is moved into a fully lowered position. A release mechanism for the wand comprises a manually operable button  241  which is connected to a catch  242 . Other connecting schemes could be used, such as a simple interference fit between the respective sleeves of the wand connector  240  and the wand. The wand connector  240  is connected to the chassis  210  by a connecting assembly  230 ,  234 . The connecting assembly comprises a connecting arm  230  and intermediate arms  234   a ,  234   b . A first end of the connecting arm  230  is pivotally connected to the wand connector  240  by a joint  231 . The other end of the connecting arm  230  is pivotally connected, by joint  232 , to a first intermediate arm  234   a . The other end of the intermediate arm  234   a  carries a peg which is constrained to slide within a slot formed on the inner wall of a first end of the second intermediate arm  234   b . Intermediate arm  234   a  is also pivotally connected to the chassis  210 . The other end of intermediate arm  234   b  is pivotally connected to the upper face of the chassis  210 . A flexible hose, shown as broken line  235 , connects the wand connector  240  directly to the sole plate  250 . A first end of the hose  235  is sealed in an airtight manner against the suction outlet of the sole plate and the second end is sealed in an airtight manner against the wand connector  240 . The provision of a pivotable joint  231 ,  232  at each end of the connecting arm  230  allows the wand connector  240 , and the wand or hose fitted to the wand connector  240 , to be moved through a wide range of positions with respect to the chassis  210 . Furthermore, the chassis  210  remains in a stable position throughout the range of positions. Conveying the airflow between the sole plate  250  and wand connector  240  by a flexible hose  235  which is separate from the connecting arm  230  permits an even greater degree of freedom of movement of the wand connected to the tool. The arrangement of intermediate arms  234   a ,  234   b  between the connecting arm  230  and chassis  210  is required in order to allow the sole plate  250  to move between a working position and a retracted position, as will be described later. In a simpler tool, such as the one shown previously in  FIG. 2 , the sole plate  250 , chassis  210  and connecting arm  230  can all share the same pivot shaft, such that the sole plate pivots about the chassis  210  and the connecting arm  230  can pivot freely about the sole plate  250  and chassis  210 . 
   The maneuverability of the tool is best illustrated by  FIGS. 7 ,  9  and  10 . In  FIG. 7  the connecting arm  230  and wand connector  240  are lying close to the floor, with the connecting arm  230  lying within the u-shaped channel of the chassis  210 . The tool will adopt this configuration as a user pushes the tool forwardly or when a user wishes to manoeuvre the tool beneath a low-lying object. In contrast,  FIGS. 9 and 10  show the connecting arm  230  and wand connector  240  in a raised position. The floor tool will usually adopt this position when a user drags the tool rearwardly. The connecting arm  230  has reached its highest position, with peg  248  pressing against flange  246 . In  FIG. 10  the wand connector has swiveled about pivot point  231  into an almost upright position. In each of these configurations, the floor tool will remain in contact with the surface. 
   A sole plate  250  is pivotally mounted to the connecting arm  230  and first intermediate arm  234   a  of the connecting assembly towards the front of the chassis. Two flanges  280  extend upwardly from the upper face of the sole plate  250 . An aperture in each flange  280  is rotatably held by a peg  233  on each side of the intermediate arm  234   a . The sole plate  250  is free to rotate, within a limited angular range, about the arm  234   a . The axis of the joint between the connecting arm  230  and intermediate arm  234  is coincident with the axis of the joint between the intermediate arm  234  and the sole plate  250  such that force applied by a user to the wand connector and hence the connecting arm  230 , is transmitted directly to the sole plate  250 . 
   The sole plate  250  of the tool will now be described in more detail. The floor tool  200  can be used in a carpet cleaning mode, where the sole plate  250  engages with, and rides along, the floor, or in a ‘hard floor’ mode where a flexible skirt  270  rides along the floor surface and the sole plate is spaced from the floor. 
     FIGS. 7 and 10  show the sole plate  250  deployed in a carpet cleaning mode. The sole plate  250  is shown in profile in  FIG. 7  and the lower, plan view of the sole plate is shown in  FIG. 8 . The sole plate  250  has a centrally mounted air inlet  256 . Two suction channels  255  extend transversely across the tool from each side of the inlet  256 . Each channel  255  terminates in a bleed air inlet on the side of the sole plate. The lower face of the sole plate has two spaced apart sharply defined edges  252 ,  253  which will be called working edges. The forward working edge  252  is defined by the intersection between the inner wall of the suction channel and a planar surface  254   a  on the lower face of the sole plate. Similarly, the rear working edge  253  is defined by the intersection between the inner wall of the suction channel and a planar surface  254   b  on the lower face of the sole plate. The working edges  252 ,  253  are sharply defined, as shown in  FIG. 7 , so as to provide an effective agitating action when the floor tool is used on carpeted surfaces. This agitating effect is further enhanced by the pivotal connection between the sole plate  250  and connection member  230 . A small radius of curvature has been found to be provide an effective agitating action on floor surfaces. The working edges  252 ,  253  extend across the full width of the floor tool. Lint pickers  258 ,  259  are positioned on the planar surfaces  254   a ,  254   b  and are spaced from the working edges  252 ,  253  so that the working edges can perform an agitating action on carpeted surfaces across their full width. Each of the lint pickers  258 ,  259  is of a conventional type, comprising a strip of material in which a plurality of tufts of fine fibre are secured. Each lint picker  258 ,  259  is secured on an arcuately-shaped support that extends outwardly from the planar surface  254   a ,  254   b  on which it is located. The spacing of the lint pickers  258 ,  259  from the adjacent working edge  252 ,  253  can be varied from the spacing as shown in the drawings. The use of lint pickers causes an increase in the force that a user requires to push or pull the floor tool across a floor surface. It would be possible to increase the width of the lint pickers  258 ,  259  to the full width of the floor tool although this would incur an increase in the push force required by a user. 
     FIGS. 11 and 12  show how the sole plate  250  of the floor tool  200  operates in use. Firstly,  FIG. 11  shows the sole plate  250  as it is pushed forwardly across a floor surface. As the tool is pushed forwardly, the sole plate  250  rotates about pivot  247 , bringing the forward working edge  252  into closer contact with the floor surface than the rear working edge  253 . The sharp edge  252  has an effective agitating effect on the surface, parting the pile of the surface and releasing dirt in a flicking action. As dirt is released, it is swept along the suction channel  254 ,  255  by the airflow in the suction channel towards suction inlet  256 . Also, forward lint picker  258  is brought into contact with the floor surface. In its lowered position, the forward lint picker  258  allows lint to pass. The rear lint picker  259  remains close enough to the surface to serve a useful blocking action on lint. 
     FIG. 12  shows the floor tool  200  as it is pushed rearwardly across a floor surface. As the tool is pushed rearwardly, the sole plate  250  rotates about pivot  247  bringing the rear working edge  253  into closer contact with the floor surface than the forward working edge  252 . The sharp edge  253  has the same effect as forward edge  252  did during the forward action, i.e. it agitates the surface, parting the pile of the surface and releasing dirt in a flicking action. Dirt is swept along the suction channel  254 ,  255  by the airflow in the suction channel towards suction inlet  256 . Rear lint picker  259  is brought into contact with the floor surface and allows lint to pass. The forward lint picker  258 , while raised higher than it would be during the forward action, remains close enough to the surface to block the passage of lint. It can be seen that once the floor tool has passed over lint, the lint becomes trapped between the lint pickers and is prised from the surface. 
   The effect of driving the floor tool from a position close to the sole plate is illustrated by  FIGS. 13 and 14 .  FIG. 13  shows a conventional floor tool, with a chassis  410 , wheels  420  and sole plate  450 . A user applies a push/pull force F V  to the tool at point A. F S  represents the suction force exerted on the floor surface by the air being drawn into the sole plate. During a backwards stroke, the forces (moment) about point C are:
 
 M   C   =l   1   ·F   S   −l   2   ·F   V  sin θ
 
Thus, for the sole plate to remain on the floor surface:
 
 l   1   ·F   S   ≧l   2   ·F   V  sin θ
 
Point C represents the point about which the floor tool will be levered from the floor surface when a force is applied in the vertical direction during a backwards stroke.
 
   In contrast,  FIG. 14  shows a floor tool in accordance with an embodiment of the invention with a chassis  410 , wheels  420  and sole plate  450  and where a user applies a push/pull force F V  to the tool at point E. As before, F S  represents the suction force exerted on the floor surface by the air being drawn into the sole plate. During a backwards stroke, for the sole plate to remain on the floor surface:
 
F S ≧F V  sin θ
 
   This is a significantly simpler requirement than that in  FIG. 13 . By bringing the outlet connector above the sole plate, the levering effect of the outlet connector is greatly reduced.  FIG. 14  shows the ideal arrangement where the point at which the push/pull force is applied to the chassis, point B, is directly above the sole plate. As the point at which the push/pull force is applied to the chassis moves away from the sole plate, i.e. rightwards in  FIG. 14 , there is an increased risk that the floor tool will be ‘pealed’ away from the floor surface during a backwards stroke since there is now a levering action on the tool. Although it is preferred that the sole plate is pivotally mounted to the chassis, the sole plate can be fixed with respect to the chassis  410  and still benefit from a reduced risk of ‘pealing’ with the push/pull force being applied in the manner shown here. 
   As described previously, in a hard floor cleaning mode the sole plate  250  is spaced away from the floor surface. In the embodiment shown in  FIGS. 8 ,  9  and  15  this is achieved by retracting the sole plate  250  within the chassis such that only skirt  270  rests against the floor surface. The skirt is formed as a dense curtain of fibres, such as Nylon fibres, which are secured, such as by crimping, to the sole plate  250 . The sole plate  250  is retractable into the position shown in  FIG. 9 , with the lower surface of the sole plate being inclined with respect to the plane of the suction opening. Skirt  270  forms a continuous curtain around the suction opening and serves to maintain a region of low pressure adjacent the floor surface. A bumper  265  on the forward edge of the chassis  210  defines a suction channel  260  which is directed downwardly towards the floor surface and extends across the full width of the tool. The bumper  265  is sufficiently spaced above the lowermost extent of the skirt (see C,  FIG. 15 ) such that large debris  269  can pass beneath the bumper where it will lie beneath suction channel  260 . Suction channel  260  communicates with the suction chamber within the chassis  210  via a conduit  262  into the main suction space within the chassis  210 . The sole plate  250  is inclined in a direction such that airflow from channel  260  can easily flow around the lower surface of the sole plate  250  and then along the suction channels  254 ,  255  towards the suction inlet  256 . Thus, airflow from channel  260  combines with airflow that is drawn beneath the skirt  270 .  FIG. 15  shows the path taken by air and debris when the floor tool is used in hard floor cleaning mode. 
     FIG. 16  is a cross section through the floor tool, showing an approximate map of pressures existing within the tool, the denser shading indicating the lower pressure regions.  FIGS. 17A and 17B  show the effect of using the floor tool on a surface. These figures show a plan view of the floor tool, moving in direction X across a floor surface. A region of low pressure is maintained within the skirted region of the tool, adjacent the floor surface. Thus, any dust lying within this region will be carried towards the suction inlet  256 . A steady flow of air enters the tool via the suction inlet  260 . This flow of air helps to maintain good separation efficiency within the separation system ( 11 ,  FIG. 1 ) of the vacuum cleaner and is particularly important with a cyclonic separation system, such as one that uses a bank of parallel cyclonic separators. The flow of air through channel  260 , and the spacing of the channel  260  from the floor surface helps to pick up any large debris from the floor surface. This debris would otherwise be pushed along the floor by the skirt  270 . The continuous skirt  270  maintains a region of low pressure within the tool. This also helps to provide good pick-up from crevices  300  on the floor surface. As shown in  FIG. 17B , as the tool moves across a crevice, the region of low pressure within the tool is connected to a region of ambient pressure outside the tool via the crevice  300 . Thus, air flows from outside the tool, through the crevice  300 , to the region of low pressure inside the tool, carrying any dust and debris from the crevice  300  along with the airflow. 
     FIGS. 18-20  show a further modification to the floor tool in which the amount of air which bleeds into the tool can be manually controlled.  FIG. 18  shows a modified form  250 ′ of the sole plate  250  of the floor tool which has previously been described. As before, each side of the main suction channel  255  of the tool has an inlet aperture  290  through which, in use, air can bleed into the suction channel  255  during carpet cleaning mode. In this modified sole plate a valve  295  is fitted on the side of the sole plate. The valve is movable between an open position, as shown in  FIG. 19 , in which a maximum amount of air can bleed into the suction channel  255 , and a closed position, as shown in  FIG. 20 , in which a lesser amount of air can bleed into the suction channel  255 . The valve can be manually slid in direction  299  between the two positions. A pair of depressions  296  on the upper face of the sole plate cooperate with a small projection on the underside of the valve (not shown) to allow the valve to be positively held in each of the two positions. The sole plate  250 ′ is further modified from sole plate  250  in that an additional bleed air inlet  292  is located on the upper face of the sole plate. A similar inlet  292  is positioned on each side of the sole plate. As can be seen in  FIGS. 19 and 20 , the valve seals the inlet  292  in the closed position. 
   In use, a user can set the valves  295  on each side of the sole plate to the same position (e.g. both valves open) or to different positions (i.e. one valve open, one valve closed), so as to select the amount of bled air and hence push resistance that they feel happy with. The amount of push resistance will vary between floor coverings and different users will prefer different amounts of push resistance. 
   In a further modification the valves  295  can be arranged such that they offer a wider range of settings. This can be achieved with an inlet  290  which varies in height in the direction  299  and a valve which can be positioned in a greater number of positions (e.g. three different positions.) The valves can be applied to a floor tool, as shown here, or to the cleaning head of an upright vacuum cleaner. In the closed position, the valve can be arranged to admit a small amount of bled air (as shown in  FIG. 20 ) or no bled air at all.