the vacuum cleaner 10 illustrated in fig1 a is an upright cleaner having a main body 12 which includes a handle 14 and dirt and dust separating means 16 for separating dirt and dust from the airflow passing through the vacuum cleaner 10 . in the vacuum cleaner 10 , the dirt and dust separating means 16 operates on the cyclonic principle and includes an upstream , low - efficiency cyclone 18 followed by a plurality of downstream , high - efficiency cyclones 20 . however , for the purposes of the present invention , the nature of the dirt and dust separating means 16 is immaterial . the main body 12 is pivotably supported on a rolling support member 22 which has an arcuate surface when viewed in the lateral direction . a cleaner head 24 is pivotably mounted on the support member 22 and air ducts 26 , 28 , 30 are provided for conducting air between the cleaner head 24 , the support member 22 and the dirt and dust separating apparatus 16 . a motor ( not shown ) is mounted inside the support member 22 for drawing an airflow into the cleaner head 24 via a suction opening ( located on the underside of the cleaner head 24 ), passing it to the dirt and dust separating apparatus 16 so that the dirt and dust can be extracted therefrom , and exhausting it to the atmosphere via the support member 22 so that the motor therein can be cooled . it is to be noted that the precise configuration of the components is not material to the present invention . the type of support member 22 illustrated in fig1 a allows the upright vacuum cleaner 10 to be maneuvered in a manner which is different from traditional vacuum cleaners which are normally mounted on wheels having fixed horizontal axes . the manner in which the vacuum cleaner 10 is maneuvered is illustrated in fig2 a and 2 b . in order to steer the vacuum cleaner 10 , the user twists the handle 14 about the axis 32 so as to cause the axis of the support member 22 to tilt . the connection between the cleaner head 24 and the air duct 26 ( which is fixed to the main body 12 ) is such that the cleaner head 24 is forced to travel laterally with respect to the normal forwards direction of travel of the cleaner head 24 . thus the cleaner head 24 moves in the direction indicated by arrow a in fig2 a and arrow b in fig2 b when it is steered around tight corners . a similar arrangement is possible in respect of cylinder vacuum cleaners . a cylinder vacuum cleaner 50 is shown in fig1 b . the cleaner 50 has a main body 52 which includes some sort of dirt and dust separating means 54 ( again shown here as being cyclonic , but this is not important ) and a motor . a flexible hose 56 is connected to the main body 52 at one end and to a wand or extension tube 58 at the other end . the cleaner head 60 is attached to the distal end of the wand or extension tube 58 . as with the upright cleaner illustrated in fig1 a , the cleaner head 60 can be attached to the extension tube 58 using the same principles , namely by providing an arcuate support member 62 whose axis of rotation can be tilted by twisting the extension tube 58 about its longitudinal axis . the connection between the cleaner head 60 and the extension tube 58 then causes the direction of the cleaner head 60 to alter which , in turn , causes the cleaner head 60 to travel laterally with respect to the original forward direction . it is this lateral movement across the surface being cleaned which can introduce difficulties in that unnecessary resistance can be encountered making the required movement difficult to achieve . a cleaner head 100 according to the invention is illustrated in fig3 , 4 a , 4 b , 4 c , 5 a and 5 b . the cleaner head 100 has a housing 102 which has an upper surface 104 and an underneath surface 106 . the upper surface 104 and the underneath surface 106 together define the housing 102 . the underneath surface 106 , which can be seen in fig5 a , is arranged to face towards the surface to be cleaned and has a suction opening 108 formed therein . the suction opening 108 extends across substantially the entire width of the cleaner head 100 . the upper surface 104 has an enlarged , generally cylindrical portion 110 extending across the width of the cleaner head 100 and arranged above the suction opening 108 in the underneath surface 106 . this cylindrical portion 110 defines a cavity which is shaped and dimensioned so as to be able to receive and house a rotatable brush bar 109 immediately above the suction opening 108 . side walls 110 a , 110 b are located at the ends of the cylindrical portion 110 . the suction opening 108 extends between the side walls 110 a , 110 b . the side walls 110 a , 110 b are substantially flat or planar so that the suction opening 108 of the cleaner head 100 is as close as possible to the side of the cleaner head 100 . when the side of the cleaner head 100 is positioned close to walls or skirting boards in a room , the collection of dirt and dust from the edge of the room is improved because the suction opening 108 is spaced from the wall or skirting board by only the thickness of the respective side wall 110 a , 110 b . the underneath surface 106 has opposing side edges 106 a , 106 b which extend along the lower edges of the sides of the cleaner head 100 . a first part 106 c , 106 d of each side edge 106 a , 106 b of the underneath surface 106 is formed by the lower end of the respective side wall 110 a , 110 b . the lower ends of the side walls 110 a , 110 b extend alongside the suction opening 108 and have sharply - defined edges which delimit the suction opening 108 . by sharply - defined is meant that the edges are angular and have a minimal radius of curvature . a second part 106 e , 106 f of each of the side edges 106 a , 106 b is located rearwardly of the first parts 106 c , 106 d . the second part 106 e , 106 f of each of the side edges 106 a , 106 b of the underneath surface 106 is upwardly curved . by this is meant that the underneath surface 106 is shaped so that , instead of the underneath surface 106 meeting the upper surface 104 at a relatively sharp corner , the upwardly curved second part 106 e , 106 f of each the side edges 106 a , 106 b presents a smoothly curved surface to the floor surface being cleaned . it will be understood that , when the cleaner head 100 is steered so that some lateral movement takes place , then the upwardly curved shape of the second part of the side edge on the side facing the direction of lateral movement will present a smoothly curved surface to the floor being cleaned . this will reduce the amount of user effort required to cause the lateral movement to take place since the floor covering will slide smoothly underneath the cleaner head 100 and the tendency of the cleaner head 100 to dig into the floor covering will be reduced . at the same time , the first part of each side edge can be placed close to a wall or skirting board so that good edge cleaning is maintained . the upward curve of the underneath surface 106 is shown in fig5 b . as can be seen , the shape of the second part 106 e , 106 f of each of the side edges 106 a , 106 b is rounded with a relatively large radius of curvature compared to the first parts 106 c , 106 d . the upwardly curved second parts 106 e , 106 f of the side edges 106 a , 106 b do not extend alongside the suction opening 108 as this could compromise the ability of the cleaner head 100 to pick up dirt and debris adjacent an edge or skirting board . in this embodiment , the upwardly curved second parts 106 e , 106 f extend along less than a half of the full length of the side edges 106 a , 106 b as can be seen in fig5 a . immediately in front of the cylindrical portion 110 is a bumper portion 112 which forms part of the upper surface 104 . a debris pick - up slot can be formed immediately behind the bumper portion 112 but this is not relevant to the present invention . rollers or wheels ( not shown ) can be provided on the underneath surface 106 adjacent the bumper strip to improve the forward movement of the cleaner head 100 across the surface to be cleaned . the upper surface 104 of the housing 102 is shaped so as to define , together with a portion of the underneath surface 106 , a motor housing 114 which is located centrally of the cleaner head 100 behind the cylindrical portion 110 . a motor ( not shown ) for driving the brush bar 109 is housed inside the motor housing 114 and an appropriate drive belt or direct drive components are provided between the motor and the brush bar 109 . located on the upper surface of the motor housing 114 is an upstanding connector 115 by means of which the cleaner head 100 is connected to the remainder of the vacuum cleaner in a manner which allows the cleaner head 100 to be steered in the way described above . the type of connection which allows this steering to take place does not form the subject matter of this application and so will not be described any further here . located behind the cylindrical portion 110 and on either side of the motor housing 114 are two rearwardly extending portions 116 , 118 . each rearwardly extending portion 116 , 118 is formed by a rearward portion of the upper surface 104 and a rearward portion of the underneath surface 106 . the height of each of the rearwardly extending portions 116 , 118 is less than half of the height of the cylindrical portion 110 , although this proportion is not important and can be varied . a further improvement in maneuverability can be achieved if the interior side edges 116 b , 118 b of the rearward portions 116 , 118 are also upwardly curved since , whenever the cleaner head 100 is moved laterally , the interior side edge of the rearward portion on the side of the cleaner head opposite the direction of movement will become the leading edge for that rearward portion . in the embodiment , it is also envisaged that the lower side edges 114 a , 114 b of the motor housing 114 will be upwardly curved so that , whenever the cleaner head 100 is caused to move laterally across a surface to be cleaned , each and every leading edge 106 e , 114 a , 118 b ; 106 f , 114 b , 116 b will present a smoothly curved surface to the floor surface being cleaned , irrespective of the direction of the lateral movement . in the event that the cleaner head 100 is shaped so that more than two rearwardly extending portions are provided , each rearwardly extending portion will have upwardly extending side edges which present a smoothly curved surface to the floor surface being cleaned . fig6 a and 6 b show rear views of two alternative designs of rearwardly extending portion which could be incorporated into the cleaner head described above . in fig6 a , the rearwardly extending portion 150 has upper side edges 152 which are relatively sharply defined . however , the lower side edges 154 are upwardly curved , as described above . the extent h of the upwardly curved edges 154 is approximately one third of the total height h of the rearwardly extending portion 150 . the alternative design shown in fig6 b is similar to that shown in fig6 a in that the rearwardly extending portion 160 has relatively sharply defined upper side edges 162 and smoothly curved lower side edges 164 . in this case , though , the extent h of the upwardly curved edges 164 is approximately one half of the total height h of the rearwardly extending portion 160 . either of the rearwardly extending portions 150 , 160 could be incorporated into the cleaner head 100 described above in place of the rearwardly extending portions 116 , 118 . furthermore , variations on these designs could equally be utilized . for example , the gaps between the rearwardly extending portions 116 , 118 and the motor housing 114 could be omitted so that the rear edge 120 of the housing 102 extends parallel to the front edge of the bumper portion 112 . in such an arrangement , only the outermost side edges of the underneath surface 106 will be upwardly curved .
a cleaner head for a cleaning appliance includes a housing having an upper surface and an underneath surface in which at least on suction opening is formed . the underneath surface has opposing side edges each having a first part which lies adjacent the suction opening or openings and forms a sharply - defined edge with the upper surface and an upwardly curved second part which is located rearwardly of the suction opening or openings . this arrangement is advantageously used in vacuum cleaners or other cleaning appliances in which a ball - type support allows an increased level of steerability involving lateral movement of the cleaner head across the surface to be cleaned . the upwardly curved side edges of the underneath surface of the cleaner head reduce the amount of effort required to achieve the steering by presenting a smoothly curved surface to the carpet or other floor covering .