Patent Publication Number: US-2022234159-A1

Title: Pole sander

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority, under 35 U.S.C. § 119, to GB Patent Application No. 2001235.7, filed Jan. 29, 2020. 
     FIELD 
     The present invention relates to a locking mechanism for a telescopic pole of a power tool, such as, a pole sander. 
     BACKGROUND 
     Pole sanders typically comprise a telescopic pole with a sanding head pivotally mounted on one end. The sanding head comprises a hood which surrounds a platen which is mounted on an output spindle which projects from the hood. Sandpaper can be attached to the platen for sanding a work surface. Alternatively, a polishing pad can be attached to polish a work surface. The output spindle and hence the platen, is rotated by an electric motor. The electric motor can be mounted on the sanding head. Alternatively, the motor can be mounted on the end of the telescopic pole remote from the sanding head. A vacuum cleaner can be attached to the sanding head, typically via a pipe which extends through the telescopic pole, to remove dust generated by the sanding action of the rotating platen from under the hood. 
     Examples of pole sanders are disclosed in EP0727281, EP2033738, DE102014103019, WO2014/086873, EP3083139 and DE102014112355. 
       FIG. 28  discloses a prior art design of locking mechanism  200  for a telescopic pole of a pole sander. The telescopic pole comprises a first pole which slides in and out of a second pole to enable the length of the pole sander to be adjusted, the first pole locating inside of the second pole when the telescopic pole is adjusted to its shortest length. 
     The locking mechanism comprises a sleeve  600  which has a first section  602  and a second section  604 . The first section  602  is used to attach the locking mechanism  200  onto the second pole of the pole sander. The second section  604  forms a clamp which can be releasably tightened around the first pole in order to releasably axially lock the first pole to the second pole. 
     The first section  602  comprises a resiliently deformable first C shaped sleeve  606  with two parallel flaps  612  extending from the edges of the first C shaped sleeve  606 . A gap (indicated by Arrow  608 ) is formed between the two flaps  612 . When no external forces are applied to the first C shaped sleeve  606 , the first C shaped sleeve  606  is held in a pre-set shape with a pre-set cross-sectional area with the width of the gap  608  between the flaps  612  being held at a pre-set distance by the resilient nature of the first C shaped sleeve  606 . The first C shaped sleeve  606  can be deformed using a bolt  610  which passes through the flaps  612  in such a manner that the width of the gap  608  can be decreased from the pre-set width, reducing the size of the pre-set cross-sectional area of the first C shaped sleeve. When no force is applied by the bolt  610 , the first C shaped sleeve  606  reverts to the pre-set shape with the width of the gap  608  reverting to the pre-set distance. 
     Formed through each flap  612  is a hole (not shown). The diameter of the hole is slightly larger than that of the shaft (not shown) of the bolt  610  but less than the head  614  of the bolt  610 . The shaft of the bolt  610  is inserted through one hole in one flap  612  and through the other hole in the second flap  612 . A nut (not shown) is then threaded onto the free end of the shaft of the bolt  610 . As the nut is screwed onto the shaft of the bolt  610 , the two flaps  612 , which are sandwiched between the head of the bolt  610  and the nut, move towards each other as the nut is screwed onto the shaft reducing the width of the gap  608 . 
     Formed in each side of the first C shaped sleeve is an elongate slot  616  which extend from the edges of the first C shaped sleeve  606  up the sides of first C shaped sleeve  606  to a second hole  618 . The elongate slots  616  and second holes  618  are capable of engaging ridges and/or pegs (not shown) on the second pole of the pole sander. 
     The locking mechanism  200  is attached to the second pole of the pole sander as follows. The first pole is separated from the second pole. The nut is unscrewed from the bolt  610  (whilst the shaft of the bolt  610  remains in the two holes of the faps  612 ) to allow the first C shaped sleeve  606  of the first section  602  to revert to its pre-set shape with the width of the gap  608  between the flaps  612  reverting to the pre-set distance. The first C shaped sleeve  606  of the first section  602  is then slid onto the end of the second pole, with the elongate slots  616  and second holes  618  aligning with ridges and pegs formed on the outer surface of the second pole. The nut is then screwed onto the shaft of the bolt  610 , the two flaps  612  which are sandwiched between the head  614  of the bolt  610  and the nut, being moved towards each other, reducing the width of the gap  608  and the size of the cross-sectional area of the second C shaped sleeve. This results in the elongate slots  616  and second holes  618  engaging with and holding onto the ridges and pegs formed on the outer surface of the second pole in addition to the first C shaped sleeve engaging with and holding the outer surface of the end of the second pole as the cross-sectional area is reduced. The nut is tightened until the first C shaped sleeve  606  is firmly secured to the second pole. The first pole is then inserted through the second section  604  of the locking mechanism  200  and into the second pole. The clamp of the second section  604  is then used to lock onto the first pole to secure the first pole within the second pole. 
     The second section  604  is described with reference to  FIGS. 28 and 29 . The second section  604  comprises a resiliently deformable second C shaped sleeve  630  with two parallel flaps  632  extending from the edges of the second C shaped sleeve  630 . A gap (indicated by Arrow  634 ) is formed between the two flaps  632 . When no external forces are applied to the second C shaped sleeve  630 , the second C shaped sleeve  630  is held in a pre-set shape with a pre-set cross-sectional area with the width of the gap  634  between the flaps  632  being held at a pre-set distance by the resilient nature of the second C shaped sleeve  630 . The second C shaped sleeve  630  can be deformed using a bolt  636 , which passes through the flaps  632 , and a cam  638  attached to the bolt  636  in such a manner that the width of the gap  634  can be decreased from the pre-set width. When no force is applied by the bolt  636  and cam  638 , the second C shaped sleeve  630  reverts to the pre-set shape with the width of the gap  634  reverting to the pre-set distance. 
     Formed through each flap  632  is a hole (not shown). The diameter of the hole is slightly larger than that of the shaft  640  of the bolt  636  but less than the head  642  of the bolt  636 . The shaft  640  of the bolt  636  is inserted through one hole in one flap  632  and through the other hole of the second flap  632 . A nut  644  is then threaded onto the free end of the shaft  640  of the bolt  636 . The nut  644  is screwed onto the shaft  640  of the bolt  636  until the two flaps  632  are sandwiched between the head  642  of the bolt  636  and the nut  644  and the flaps  632  have been moved to a second pre-set distance from each other, the two flaps  632  being held against the head of the bolt  636  and the nut  644  by the resilient nature of the second C shaped sleeve  630  urging the flaps  632  apart. 
     The cam  638  is pivotally mounted on a rod  646  which passes though the head  642  of the bolt  636 . The cam  638  can pivot about an axis, which extends longitudinally along the length of the rod  646 , perpendicularly to the longitudinal axis of the shaft  640  of the bolt  636 . An edge  648  of the cam  638  abuts against the side of one of the flaps  632 . The cam  638  is circular in shape with the rod  646  locating eccentrically relative to the centre of the circular cam  638 . As such, as the cam  638  is rotated, the distance of the edge  648  of the cam  638 , which abuts against the side wall of the flap  632 , from the rod  646  changes dependent on the angular position of the cam  638  relative to the flap  632 . The side wall of the flap  632  remains in contact with the edge  648  of the cam  638  due to the resilient nature of the second C shape sleeve  630  which biases the two flaps  632  away from each other with one of the flaps  632  being biased into engagement with the edge  648  of the cam  638 . Attached to one side of the cam  638  is an arm  658  which is curved along its length. The arm  658  is used by an operator to rotate the cam  638  in order to move the flap  632  abutting against the edge  648  of the cam  638 , altering the size of the gap between the two flaps  632  between a large gap and a small gap, the flaps  632  being moved due to the resilient nature of the second C shaped sleeve  630 . A groove  650  is formed around the second section  604 . The curve of the arm  658  is the same as the curve of the base of the groove  650 . When the arm  658  is pivoted so that it is perpendicular to the base of the groove  650 , the size of the gap between the flaps  632  is the greatest (when the position of the nut  644  on the shaft  640  of the bolt  636  remains fixed). When the arm  658  is pivoted so that it is locates within the groove  650  so that the arm  658  is flush with the base of the groove  650  (whilst the position of the nut  644  on the shaft  640  of the bolt  636  remains fixed), the size of the gap between the flaps  632  is the smallest. 
     The operation of the clamping mechanism of the second section  604  will now be described. The locking mechanism is attached to the end of the second pole as described above. The arm  658  of the second section  604  is then pivoted so that it is perpendicular to the base of the groove  650  so that the size of the gap between the flaps  632  is the greatest. This results in the largest cross-sectional area of the second C shaped sleeve  630  which is greater than the cross-section area of the first pole. The first pole is then inserted through second C shaped sleeve  630  of the second section  604  of the locking mechanism  200  and into the second pole. The arm  658  is then pivoted so that it is located in the groove  650  flush with the base of the groove  650  so that the size of the gap between the flaps  632  is the smallest. This results in the smallest cross-sectional area of the second C shaped sleeve  630  which is slightly smaller than the cross-section area of the first pole. As such, the second C shaped sleeve  630  engages with and holds the outer surface of the first pole as the cross-sectional area is reduced. This locks the first pole to the locking mechanism which in turn is attached to the second pole. 
     The problem with the design of the first section  602 , which is used to attach the locking mechanism  200  to the second pole, is that the nut and bolt can be over tightened resulting in excess compressional force being applied to the first C shaped sleeve  606 , resulting in the end of the second pole becoming deformed. If the first pole is located inside of the end of the second pole, the excessive compressive force can result in the second pole engaging with the first pole if it becomes deformed, preventing movement of the first pole within the second pole. As such, the position of the first pole becomes permanently fixed to the second pole and therefore cannot be telescoped in or out of the second pole, regardless of whether the clamping mechanism of the second section  604  is released or clamped. 
     SUMMARY 
     The present invention provides an alternative way of attaching the locking mechanism to the second pole which avoids the problems associated with the prior art design described with reference to  FIGS. 28 and 29 . 
     According to a first aspect of the present invention, there is provided a locking mechanism capable of locking the position of a first pole relative to a second pole of a power tool comprising a telescopic pole comprising at least two poles, the first pole capable of telescoping in and out of the second pole, the second pole comprises at least one recess ( 694 ). In an embodiment, the locking mechanism includes a first section capable of connecting to the second pole of a power tool and a second section capable of connecting to the first pole of a power tool. In an embodiment, the first section comprises: a sheaf which is capable of mounting on and surrounding at least part of the second pole; a resilient tab connected to the sheaf; and a catch formed on the tab, wherein the catch is capable of locating within the recess of a second pole when the sheaf is mounted on the second pole. 
     According to a second aspect of the present invention, there is provided a power tool comprising a telescopic pole comprising at least two poles, a first pole capable of telescoping in and out of a second pole wherein the second pole comprises at least one recess; and a locking mechanism capable of locking the position of the first pole relative to the second pole, the locking mechanism comprising a first section capable of connecting to the second pole and a second section capable of connecting to the first pole. In an embodiment, the first section comprises: a sheaf which is capable of mounting on and surrounding at least part of the second pole; a resilient tab connected to the sheaf; and a catch formed on the tab, wherein the catch locates within the recess when the sheaf is mounted on the second pole. 
     In either aspect of the invention, the recess can be a window which extends through the wall of the second pole. The catch can extend through the window. 
     In either aspect of the invention, the catch may comprise a taper. Furthermore, the sheaf may mount on and surround the end of the second pole. The resilient tab may be connected at one of its ends to the sheaf. 
     In either aspect of the invention, there may be provided a cut out in the wall of the sheaf, the tab being connected at one of its ends to an edge of the cut out, the tab extending, at least in part, across at least part of the cut out. The at least part of the tab may extend within the plane of the cut out. 
     In either aspect of the invention, the tab may extend in a direction parallel to the longitudinal axis of the sheaf. 
     In either aspect of the invention, the tab may be planar. 
     In either aspect of the invention, the cut out may rectangular in shape. 
     In either aspect of the invention, the longer edges of the rectangular cut out may extend in a direction parallel to the longitudinal axis of the sheaf. 
     In either aspect of the invention, the tab may connect to one of the shorter edges of the cut out. 
     In either aspect of the invention, the catch may be formed on the tab adjacent the end of the tab. 
     In either aspect of the invention, the catch may extend in a direction perpendicular to that of the plane of the tab. 
     In either aspect of the invention, the tab may flex to allow the catch to move in a direction perpendicular to that the longitudinal axis of the sheaf. 
     In either aspect of the invention, the tab may locate inside of the second pole. The catch may project from inside of the second pole into the recess. 
     In either aspect of the invention, when the first pole is located inside of the second pole, the first pole locates behind the tab to prevent movement of the tab, locking the catch within the recess. 
     According to a third aspect of the present invention there is provided method of attaching a locking mechanism in accordance with either the two previous inventions comprising the step of: 
     1) sliding the sheaf of the locking mechanism onto the end of the second pole until the catch engages with the recess, where the catch comprises a taper; 
     2) sliding the sheaf onto the end of the pole until a front edge ( 673 ) engages with the taper of the catch; 
     3) continuing to slide the sheaf onto the pole to cause the catch to move out of the way by bending the resilient tab with the front edging slidingly engages the taper; 
     4) continuing to slide the sheaf onto the pole until the catch aligns with the recess; 
     5) allowing the catch to enter the recess under the biasing force of the resilient tab. 
     The method may further comprise the step sliding the catch along inside wall of the second pole after it has been moved out of the way prior to aligning with the recess. 
     The tab may locate inside of the second pole when the catch has been moved out of the way and/or when the catch is aligned with the recess and/or when the catch has entered the recess. 
     The method may further comprise the step of sliding the first pole into the second pole to abut against the tab to lock the catch in the recess. 
     In any of the three aspects of the invention, the first pole may a comprise a single aluminium tube with an internal wall to form two passageways; wherein the second pole may comprise a first tube and a second tube mounted in parallel to the first tube, inside of the first tube, wherein an end of the second tube of the second pole locates inside one of the passageways of the tube of the first pole; and wherein the tube and internal wall of the first pole locate inside of the first tube of the second pole. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations and are not intended to limit the scope of the present disclosure. 
         FIG. 1  shows a top view of the pole sander; 
         FIG. 2  shows a side view of the pole sander; 
         FIG. 3  shows a vertical cross-sectional view of the pole sander; 
         FIG. 4  shows a perspective view of the sanding head; 
         FIG. 5  shows an underside view of the sanding head with the platen removed; 
         FIG. 6A  shows a vertical cross-sectional view of the edge of the sanding head; 
         FIG. 6B  is the same as  FIG. 6A  with the addition of hatching to show cross sectional area of gap between edge of the platen and the inner wall; 
         FIG. 7  shows a perspective view of the brush ring; 
         FIG. 8  shows a view of part of the top side of the plate with the leaf spring of the brush ring  132  passing through an aperture from below the plate to attach to the top side of the plate; 
         FIG. 9  shows a schematic diagram showing how the two poles of the elongate body are telescopically connected to each other; 
         FIG. 10  shows the seals which connect between the two poles of the elongate body; 
         FIG. 11A  shows the seal for the first pole  196  being attached to the first pole  196 ; 
         FIG. 11B  shows a vertical cross section of the seal for the first pole  196  being attached to the first pole  196 ; 
         FIG. 11C  shows the seal for the first pole  196  mounted on the first pole  196 ; 
         FIG. 12  shows the seals adjacent the ends of the aluminium tubes of the poles; 
         FIG. 13  shows a perspective cross section showing how the aluminium tubes and seals of the two poles of the elongate body are telescopically connected to each other; 
         FIG. 14  shows a perspective cross section showing how the aluminium tubes and seals of the two poles of the elongate body are telescopically connected to each other; 
         FIG. 15  shows a top view of the sanding head; 
         FIG. 16  shows a vertical cross section of the sanding head and lower end of the first pole  196 ; 
         FIG. 17  shows the underside view of the sanding head including the platen; 
         FIG. 18  shows the platen; 
         FIG. 19  shows the rear housing with one of the clam shells removed; 
         FIG. 20  shows a vertical cross section of the rear housing; 
         FIG. 21  shows a top perspective view of the sanding head; 
         FIG. 22  shows the extension tube inside the handle section of the rear housing with the vacuum nozzle detached; 
         FIG. 23  shows the extension tube inside of the handle section of the rear housing with the vacuum nozzle attached; 
         FIG. 24  shows the rear end of the extension tube with the vacuum nozzle detached; 
         FIG. 25  shows the rear end of the extension tube with the vacuum nozzle attached; 
         FIG. 26A  and  FIG. 26B  show a first angle of the tubular passageway of the hood; 
         FIG. 27A  and  FIG. 27B  shows a second angle of the tubular passageway; 
         FIG. 28  shows a prior art of locking mechanism for a telescopic pole of a pole sander; 
         FIG. 29  shows a sketch of a cross section of the prior art locking mechanism in the direction of Arrows M shown in  FIG. 28 ; 
         FIG. 30  shows a locking mechanism according to the present invention mounted on the elongate body of a pole sander; 
         FIG. 31  shows an exploded view of the first and second poles of the elongate body together with the locking mechanism as shown in  FIG. 30 ; and 
         FIG. 32  shows a cross sectional view of the locking mechanism mounted on the elongate body of a pole sander shown in  FIG. 30 . 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 to 3 , the pole sander comprises a sanding head  100  pivotally attached to one end of an elongate body  102  and a rear housing  104  attached to the other end. 
     The elongate body  102  is telescopic and is formed from two poles  196 ,  198 , one of which slides in an out of the other as described in more detail below. 
     The sanding head  100  connects to the end of the elongate body  102  via a pivot mechanism  110  which is described in more detail below. The sanding head  100  comprises a hood  112  on top of which is mounted an electric motor  114 . The motor  114  is a DC brushless motor  114 . The motor  114  is enclosed by a motor housing  120  which is cup shaped and surrounds the top and sides of the motor  114 . The motor housing  120  attaches to the top of a gear housing  122  which encloses a planetary gear set  124 . The gear housing  122  mounts on top of the hood  112 . The motor  114  is drivingly connected via the planetary gear set  124  to an output spindle  118  having a longitudinal axis  126  about which it rotates and which is located below the hood  112 . Attached to the end of output spindle  118  is a circular platen  116  which extends radially outwards from the output spindle  118 . When the motor  114  is activated, the motor  114  rotationally drives the output spindle  118  and hence the platen  116  about a drive axis  126 . 
     A flexible dust extraction pipe  128  attaches to the top of the hood  112  on one side of the motor  114 . An aperture  130  is formed through the hood  112 . The end of the flexible pipe  128  surrounds the aperture  130 . As such air can be drawn from beneath hood  112  through the aperture  130  and into the flexible pipe  128 . This enables dust and debris generated during the operation of the pole sander to be removed from under the hood  112  by applying a suction force to the flexible pipe  128 . The operation of the dust extraction of the pole sander is described in more detail below. 
     A brush ring  132  attaches to the edge of the hood  112 . The brush ring  132  is described in more detail below. 
     The rear housing  104  is formed two plastic clam shells  134  which clamp to the end of the elongate body  102 . The rear housing  104  comprises a forward mount section  136  and rear handle section  138 . A battery mount  140  is formed on the lower surface of the mount section of the rear housing  104 . A battery pack  142  can be slid in a forward direction (Arrow M in  FIG. 19 ) onto the battery mount  140  to attach it to the rear housing  104  and in a rearward direction to detach it from the battery mount  140 . The design of the battery mount  140  and battery  142  are known in art and therefore will not be described in any more detail. 
     Control electronics  144  for the motor  114  are mounted inside of forward mount  136  section of the rear housing  104 . The control electronics  144  are connected to the motor  114  via an electric cable  146  which passes through a second passageway  148  of the elongate body  102  through the length of the elongate body  102 . The control electronics  144  control the operation of the brushless motor  114 . 
     A lock on/lock off switch  150  is mounted on the top of rear housing  104  where the rear handle section  138  connects to the forward mount section  136 . An operator can use the lock on/lock off switch  150  to activate the motor  114 . 
     An operator can support the pole sander by grasping the rear handle section  138  of the rear housing  104  in one hand and the elongate body  102  in the other. The operator can switch the pole sander on or off using the thumb of the hand grasping the rear handle section  138 . 
     A vacuum connection nozzle  152  is mounted on the rear of the rear housing  104  which connects to a first passageway  154  which extends through the length of the elongate body  102 . The other end of the second passage  154  connects to the flexible pipe  128 . A vacuum cleaner (not shown) can be connected to the nozzle  152  and draw air from under the hood  112 , through the flexible pipe  128 , through the first passage  154  in the elongate body  102 , through the nozzle  152  and into a vacuum cleaner. 
     The hood  112  will now be described with reference to  FIGS. 4 to 6 . 
     The hood  112  comprises a circular plate  156  which extends radially from a central circular hole  158  through which the output spindle  118  projects. Formed on the underside of the plate  156  around the edge is a peripheral wall  160  which projects perpendicularly to the plane of the circular plate  156 . An inner circular inner wall  162  is formed on the underside of the plate  156  in close proximity to and concentrically with the peripheral wall  160 . The inner wall  162  has the same height as the peripheral wall  160  and extends in the same direction that is parallel to the peripheral wall  160 . A circular trough  164  is formed between the two walls  160 ,  162 . Six rectangular apertures  166  are formed through the base of the trough  164 . The apertures  166  are located equidistantly around the centre of the plate  156  in a symmetrical fashion. A chamber  166  is formed between the inner wall  162  and the underside of the plate  156 . 
     Formed through the plate  156  between the inner wall  162  and the central hole is an arc shaped aperture  130  which allows air and debris to pass through the plate  156 . The aperture  130  has three edges, a first straight edge  170  which extends tangentially to the longitudinal axis  126  of the output spindle  118 , a second edge  172  of equal length which extends from the end of the first edge  170 , perpendicularly to the first edge  170 , in a direction away from the longitudinal axis  126  of the output spindle  118 , and a third curved edge  174  extending between the ends of the first and second edges  170 ,  172 . The circular plate  156  has a radius R. The whole of the arc shaped aperture  130  is located at a distance of less than half of the radius from longitudinal axis  126  of the output spindle  118  or the centre of the plate  156  (&lt;R/2). 
     Integrally formed on the top side of the plate  156  is a curved wall  178  which forms a tubular passageway  176  from the arc shaped aperture  168  to an opening where the flexible pipe  128  is attached. Where the tubular passageway  176  connects to the arc shaped aperture  130 , it is shaped to engage with the arc shaped aperture  130  at certain angles to maximise the air flow efficiency. 
     Referring to  FIGS. 26A and 26B , the first angle of the exit of the tubular passageway  176  is located in a vertical plane  300  which passes through axis of rotation  126  of the output spindle  118  across the end of the tubular passage  176  adjacent the arc shaped aperture  168 . The angle  302  in this plane  300  between the axis of rotation  126  of the output spindle  128  and the direction of the tubular passageway  176  is less than 90 degrees (perpendicular) but greater than 0 degrees (parallel) and is ideally between 20 degrees and 60 degrees. 
     Referring to  FIGS. 27A and 27B , the second angle of the exit of the tubular passageway  176  is located in a vertical plane  304  which extends tangentially to the axis of rotation  126  of the output spindle  128 , the part of the plane  304  which passes through the exit of the tubular passageway  176  being the closest part to the axis of rotation  126  of the output spindle  118 . The angle  308  in this plane  304  between the plane of the circular plate  156  of the hood  112  and the direction of the tubular passage  176  in the turning direction  306  of the platen  116  is less than 90 degrees and is ideally between 20 degrees and 60 degrees. 
     The hood  112  is formed in a one-piece construction from plastic. 
     The brush ring  132  will now be described with reference to 6 to 8. 
     The brush ring  132  comprises a plastic circular ring  180  which is sized so that it is capable of locating inside of the trough  164 . Extending perpendicularly from the bottom side of the ring  180  are a series of bristles  182 . Attached to the opposite top side of the brush ring  132  are the ends  184  of six leaf springs  186 . The leaf springs  186  are formed from sheet metal and are resiliently deformable in a direction perpendicular to the plane of the sheet. The leaf springs  186  comprises a central section  188  located between two end sections  184 ,  190 . The end sections  184 ,  190  extend in a direction parallel to the top surface of the ring  180 . The central section  188  of the leaf springs  186  extends upwardly at a slight angle to the plane of the circular ring  180 . Each central section  188  of each leaf spring  186  extends through the rectangular aperture  166  in the trough  164  and attaches to the top side  194  of the plate  156  as shown in  FIG. 8 . The leaf springs  186  bias the ring  180  to a position where it is located at a distance from the base of the trough  164  as shown in  FIG. 6 . In this position, the bristles  182  project below the hood  112 . When the sanding head  100  is placed against a work surface, the bristles  182  engage with the work surface. When the sanding head  100  is pushed against the work surface, the brush ring  132  is pushed into the trough  164  against the biasing force of the leaf springs  186 . The leaf springs  186  ensure that the bristles  182  are biased into engagement with the work surface. When the sanding head  100  is removed from the surface, the brush ring  132  returns to its original position due to the resilient nature of the leaf springs  186 . 
     A plastic cover  195  is located over the topside of the hood  112  enclosing the ends  190  of the leaf springs  186  attached to the top side  194 . 
     The telescopic elongate body  102  will now be described with reference to  FIGS. 1 to 3 and 9 to 14 . 
     The pole sander has an elongate body  102  comprising a first pole  196  which is capable of sliding in and out of a second pole  198  in a telescopic manner to enable the length of the pole sander to be adjusted. A locking mechanism  200  is used to lock the first pole  196  to the second pole  198  when the two poles  196 ,  198  have been telescoped to a preferred length. 
     Inside both of the poles  196 ,  198  are two passageways  148 ,  154  which run the length of the both poles  196 ,  198 . The first larger passageway  154  is used to transport air (due to suction) and entrained dust and debris, generated during the use of the pole sander, through the poles  196 ,  198  from the working end to a vacuum nozzle  152  at the opposite end, the nozzle  152  being connected to a vacuum cleaner. The second smaller passageway  148  is used as a conduit for electric cable  146  which provide power and control signals from a control electronics  144  for the electric motor  114  mounted in the sanding head  100 . 
     The first pole  196  comprises a single aluminium tube with an internal wall  202  located inside of the tube, which runs the length of the tube to form the two passageways  148 ,  154  which run the length of the first pole  196 . The first larger passageway  154  forms part of the first passageway which is used to transport air. The second smaller passageway  148  forms part of the passageway which is used as a conduit for the electric cable  146 . A first seal  204  attaches to the end of the first pole  196  which is inserted into the second pole  198 . The shape of the seal  204  corresponds to that of the end of the aluminium tube and internal wall  202 . The first seal  204  provides a seal between the first pole  196  and the second pole  198 . It also acts as a slide bearing. 
     The second pole  198  comprises two aluminium tubes  206 ,  208 . The second aluminium tube  208  locates inside of the first aluminium tube  206  and runs the full length of the first tube  206 , their longitudinal axes being parallel to each other. The second aluminium tube  208  forms part of the first passageway which is used to transport air and dust or debris. The first aluminium tube  206  forms part of the passageway  154  which is used as a conduit. A second seal  210  is attached to the end of the first aluminium tube  206  into which the first pole  196  is inserted. The shape of the second seal  210  corresponds to that of the end of the aluminium tube  206 . A third seal  212  is attached to the end of the second aluminium tube  208  which is inserted into the second passage  148  way of the first pole  196 . The shape of the third seal  212  corresponds to that of the end of the second aluminium tube  208 . The seals  210 ,  212  provides a seal between the first pole  196  and the second pole  198 . They also act as slide bearings. The two tubes  206 ,  208  are connected to each other at their ends remote from the seals  210 ,  212  so that relative movement between the two tubes  206 ,  208  is prevented. 
     The poles  196 ,  198  are assembled as following. The end with the third seal  212  of the second aluminium tube  208  of the second pole  198  is inserted into the second passageway  148  of the first pole  196  through the seal  212 . The end of the first pole  196  with the first seal  204 , with the second aluminium tube  208  inside of it, is then inserted into the end of the first aluminium tube  206  of the second pole  198  with the second seal  212 . 
     The poles  196 ,  198  can be telescopically locked using the locking mechanism  200  described below. 
     The larger passageway  154  in the first pole  196  connects directly to an end of the flexible tube via a collar  214 . The larger passageway  154  in the second pole  198  connects to an end of the vacuum attachment nozzle  152  via an extension tube  216 . 
     As the poles  196 ,  198  are made from aluminium, they are conductive. As such the poles,  196 ,  198  are electrically grounded by being electrically connected to neutral in the electronic control electronics  144  in the rear housing  104 . in order to ensure that the whole of elongate body  102  is grounded, ideally, the seals  204 ,  210 ,  212  are manufactured from electrically conductive material. This ensures a good electrical connection between the two poles  196 ,  198 . 
     In addition, or as an alternative, metal contacts  218  such as leaf springs, at least one electric cable and/or an electrical connector can be connected between the telescopic poles  196 ,  198  I to ensure electrical conductivity between the poles  196 ,  198 . Ideally, they are located between the overlapping parts of the telescopic poles  196 ,  198 . 
     Referring to  FIGS. 30 to 32 , the locking mechanism  200  for locking the first pole  196  to the second pole  198  according to the present invention will now described. 
     The locking mechanism comprises a sleeve  600  which has a first section  602  and a second section  604 . The first section  602  is used to attach the locking mechanism  200  onto the second pole of the pole sander. The second section  604  forms a clamp to releasably axially lock the first pole to the second pole. The second section  604  is the same as that of the prior art design described above with reference to  FIGS. 28 and 29  in relation to the prior art design. The first section  602  is connected at a top half to the second section  604  by a bridge  660  but is separated at a bottom half by an elongate gap  662 . 
     The design of the first section  602  is new and forms an embodiment of the invention as covered by the claims. 
     The cross-sectional shape of the aluminium tube the first pole  196  is oval. The cross-sectional shape of first aluminium tube  206  of the second pole  198  is also oval. 
     The first section  602  comprises a tubular sheaf  670  which has an oval shape in cross-section and which is capable of sliding over the end of the first aluminium tube  206  of the second pole  198 . A rectangular cut out  672  is formed through one side of the sheaf  670  which forms an aperture through the side of the sheaf  670 . The cut out  672  is rectangular in shape, with the longer edges  674  of the rectangular cut out  672  extending in a direction parallel to a longitudinal axis  676  of the sheaf  670 . A resilient planar rectangular tab  678  is connected at one of its ends to a shorter edge  680  of the cut out  672 , the tab  678  extending across the cut out  672  in a direction parallel to the plane of the cut out  672  and, in its lengthwise direction, parallel to the longer edges  674  of the cut out  672 . The resilient tab  678  is connected at one end to the shorter edge  680  of the cut out  672  which is located closest to the section  604 . The free end of tab  678  can flex in a direction perpendicular to the plane of the cut out  672 . The ratio of the dimensions of the shorter sides of the tab  678  to the longer sides of the tab  678  is the same as that of the ratio of the dimensions of the shorter edges  680  of the cut out  672  to the longer sides  674  of the cut out  672 . The size of the sides of the tab  678  are slightly smaller than those of the cut out  672  leaving a gap between the longer sides of the tab  678  and the longer edges  676  of the cut out  672  and between the free end of the tab  678  and the short edge  680  of the cut out  672  adjacent the free end. 
     The thickness T 1  of the tab  678 , as best seen in  FIG. 32  is less than half of the thickness T 2  of the sheaf  670 . The base  684  of the tab  678  is co-planer (flush) with that of the inner wall  686  of the sheaf  670 . A catch  682  is formed on the tab  678  adjacent the free end of the tab  678 . The catch  682  extends in a direction perpendicular to the plane of the tab  678  away from the base  684  into the space formed within the cut out  678 . The catch  682  comprises a forward-facing tapered edge  688  which starts at a forward edge of a ridge  689  formed on the end of the catch  682  and which is orientated so that it extends in a direction away from the second section  604 . The catch  682  also comprises a smaller rearward facing tapered edge  690  which starts at a rearward edge of the ridge  689  and which is orientated so that it extends in a direction towards from the second section  604 . 
     The diameter of the first aluminium tube  206  is greater than that of the inner wall  686  of the sheaf  670 . Therefore, the inner wall of the front end of the sheaf  670  has been cut away to provide a slot  692  into which the front end of the first aluminium tube  206  of the second pole  198  can be slid. The tab  678  has a diameter relative to the axis  676  of the sheaf  670  that is smaller than that of the aluminium tube  206  (the outer diameter of the tab  678  relative to the axis  676  of the sheaf  670  being the same as the inner diameter of the aluminium tube  206 ) so that the tab  670  locates inside of the aluminium tube  206  when the sheaf  670  is mounted on the end of the aluminium tube  206  (with the outer surface of the tab  678  located against the inner surface of the aluminium tube  206  as shown in  FIG. 32 ). 
     The front end of the first aluminium tube  206  of the second pole  198  comprises a series of windows  694  which are located adjacent the front edge of the first aluminium tube  206  of the second pole  198  equidistantly around the circumference of the end of the first aluminium tube  206 . The windows  694  are of a suitable size so that, when the sheaf  670  is mounted on the front end of the aluminium tube  206 , each window  694  can receive the catch  682 , the catch  682  being able to pass through each window  694  when aligned with it. The windows  694  are located rearward from the front edge of the aluminium tube  206  such that, when the catch  682  is located in a window  694 , the front edge locates within the slot adjacent the rear edge of the cut out  672 . 
     The locking mechanism  200  is attached to the first aluminium tube  206  of the second pole  198  as follows. 
     The front end of the first aluminium tube  206  of the second pole  198  is slid into the front end of the sheaf  670  by the front edge  673  of the font end entering into and sliding rearwardly along the slot  692  of the front end of the sheaf  670 . As the front end slides further into the slot, the front edge engages with the forward facing taper  688  of the catch  682 . Continued movement of the front edge  673  causes the tab  678  to bend inwardly towards the axis  676  of the sheaf  670  due to the shape of the front taper  688  as it pushes the catch  682  out of the way. As the front end of the aluminium tube  206  continues to enter the sheaf  670 , the end of the catch  682 , which has been pushed inwardly out of the way, engages with and slides along the inside wall of the aluminium tube  206  with the tab  670  locating inside of the aluminium tube  206 . The aluminium tube  206  continues to enter the sheaf  670  until the catch  682  aligns with a window  694  on the inside of the aluminium tube  206  (this may require some rotation of the aluminium tube within the sheaf  670 ). When the catch  682  aligns with the window  694 , it moves outwardly to enter the window  694  due to the resilient nature of the tab  678  which reverts back to its original shape. When the catch  682  is located inside of the window  694 , it is held in place by the resilience of the tab  678  which seeks to maintain its original shape. When the catch  682  is located inside of the window  694 , the base  684  of the tab  678  aligns with the inner wall of the sheaf  670  so that they are flush with each other with the outer surface of the tab  678  located against the inner surface of the aluminium tube  206  as shown in  FIG. 32 . 
     After the sheaf  670  is mounted on the end of the aluminium tube with the catch  682  located within a window  694 , the aluminium tube of the first pole  196  is inserted into the second section  604  of the sleeve  600  and then into the end of the first aluminium pole  206  of the second pole  198 . When the aluminium tube of the first pole  196  has been inserted into the end of the second pole  198 , it is surrounded by the first aluminium tube  206  of the second pole  198 , which in turn is surrounded by the sheaf  670 . The aluminium tube  206  of the first pole  196  locates against the base  684  of the tab  678 , preventing it from moving perpendicularly to the plane of the cut out  672  as best seen in  FIG. 32 . As such, the tab  678  is held sandwiched between the aluminium tube of the first pole  196  and the first aluminium tube  206  of the second pole  198 . As such, the catch  682  is prevented from leaving the window  694  in the first aluminium tube  206 . Therefore, when the first pole  196  is inserted into the second pole  198 , the sheaf  670  is locked onto the second pole  198 . The position of the first pole  196  can then be locked relative to the second pole  198  using the clamping mechanism in the second section  604 . 
     In order to remove the sheaf  670  from the first aluminium tube  206  of the second pole  198 , the clamping mechanism of the second section  604  is released and the first pole  196  is first removed from the first aluminium tube  206  of the second pole  198 . The catch  682  is then pushed inwardly, moving it out of the window  694  into the first aluminium tube  206 . The sheaf  670  can then be slid off the end of the first aluminium tube  206  of the second pole  198 , the catch  682  sliding along the inside wall of the first aluminium tube  206  of the second pole  198  as it does so until it disengages with the second pole  198 . 
     It will be appreciated that the second aluminium tube  208  of the second pole  198  remains located inside of the first aluminium tube  206  of the second pole  198  during the procedure of attaching and using the locking mechanism  200  on the first and second poles  198 . 
     Whilst the sheaf  670  described above completely surrounds the end of the first aluminium tube  206  of the second pole  198 , it will be appreciated that the sheaf  670  can partly surround the tube  206 , the sheaf  670  extending in a circumferential direction around the first aluminium tube  206  sufficiently to enable the sheaf  670  to slide on an off the end of the first aluminium tube  206  in an axial direction but prevent the sheaf  670  from being removed from the first aluminium tube  206  in another direction e.g. perpendicular to the axis  676  of the first aluminium tube  206 . 
     Whilst in the embodiment, the cross sectional shapes of the aluminium tube the first pole  196  and the cross-sectional shape of first aluminium tube  206   206  of the second pole  198  are oval, it will be appreciated that the shape of cross sections could be over shapes such as round, square, rectangular triangular etc. whilst the design of the first section  602  could still function in the same manner. 
     The pivot mechanism  110  will not be described with reference to  FIGS. 4, 15 and 16 . 
     Attached to the end of the first pole  196  in a fixed manner is an end housing  220  (see  FIGS. 1 and 2 ) comprising two clam shells  222  attached to each other using screws (only one clam shell is shown in  FIG. 4 ). The pivot mechanism  110  connects the sanding head  100  to the first pole  196  via the end housing  220 . 
     The pivot mechanism  110  comprises a fork  224  having two arms  226 , a central interconnecting section  228  and a pole support section  230 . The two arms  226  extend in parallel in a forward direction from the ends of the central interconnecting section  228  in a symmetrical manner. The pole support section  230  connects to the centre of the interconnection section  228  on the opposite side of the two arms  226  and projects in a rearward direction opposite but parallel to that of the two arms  226 . 
     Formed in each side of the gear housing  122  in a symmetrical manner are threaded apertures. The axis  232  of the of the apertures are aligned with each other and are horizontal. Formed in the ends of the two arms  226  are apertures. When the fork  224  is attached to the sanding head  100 , the ends of the two arms  226  align with the apertures formed in the gear housing. A bolt  234  is passed through each aperture in the end of each arm  226  and screw into the threaded aperture in the side of the gear housing  122  to attach the fork  224  in a pivotal manner. The fork  224  can pivot around the bolts  234  about a horizontal sideways axis  232 . 
     Rigidly mounted in a recess formed in the end of the pole support section  228  is the rear half of an axle  234 . The axle  234  projects rearwardly. Formed in the end housing  220  is an elongate recess  236 . The recess  236  extends in a direction parallel to the longitudinal axis of the first pole  196 . The forward half of the axle  234  is mounted inside of the recess  236  via two bearings  240  supported by the end housing in the side walls of the recess. The bearings  240  allow the axle to rotate within the recess. The axle can rotate about an axis which is parallel to the longitudinal axis of the first pole  196  and which passes through the length of the second smaller passage  148  of the elongate body  102 . This allows the fork  224 , together with sanding head  100 , to pivot about an axis which is parallel to the longitudinal axis of the first pole  196  and which passes through the length of the second smaller passage  148  of the elongate body  102 . The axis also crosses the output axis  126  of the drive spindle. 
     The sanding head  100  has a centre of gravity  242 . As best seen in  FIG. 15 , the axis of pivot  232  of the fork  224  on the sanding head  100  is located forward (distance D in  FIG. 15 ) of the centre of gravity  242 . Furthermore, the axis of pivot  232  of the fork  224  on the sanding head  100   100  is located forward of the drive axis  126  of the output spindle  118 . This allows the sanding head  100 , which can freely rotate about the bolts  234 , to automatically pivot to an angular position where it is parallel to a wall when the sanding head  100  is raised by an operator. 
     When the plane of the platen  116  is parallel to the longitudinal axis of the elongate body  102  as shown in  FIG. 16 , the axis of rotation of the axle is located below the centre of gravity  242  of the of the sanding head  100 . 
     The design of the platen  116  will now be described with reference to  FIGS. 17 and 18 . 
     The platen  116  comprises a plastic disc  244  with a metal insert  246  located at the centre. Attached to the bottom of disk is layer made of a soft foam  248 . Attached on the opposite side of the soft foam layer is a sheet of Velcro  250 . The Velcro  250  is used to attach the sandpaper to the platen  116 . 
     The platen  116  is attached to the output spindle  118  using a bolt  252 . The platen  116  is circular and extends radially from the drive axis  126  in a direction perpendicular to the drive axis  126 . Two sets of air holes  254 ,  256  are formed through the platen  116  to allow air and debris to pass through the platen  116 . The first set  254  are located towards the outer edge of the platen and in a symmetrical manner around the axis  126 . The holes  254  of the first set are tear shaped with the narrower end pointing towards the centre. The straight sides of the holes  254  align with the centre of the platen  116 . The second set of holes  256  are located between the first set  254  and the centre of the platen  116  in a symmetrical manner. The holes  256  of the second set are smaller than those of the first set. The holes  256  of the second set are tear shaped with the narrower end pointing towards the centre. The straight sides of the holes  256  align with the centre of the plate  116 . 
     Referring to  FIG. 6A , a space  258  is formed between the top of the platen  116  and the underside of the hood  112 . In the present design, the size H of the space is kept to a minimum. This ensures that the air speed above the platen  116  is kept as high as possible. If the air speed slows, entrained dust and debris will deposit on the surface of the underside of the hood  112  and therefore will build up. By keeping the air speed high, the dust remains entrained and therefore can be drawn out the flexible pipe  128  due to the suction from a vacuum cleaner. 
     The air flow around the rotating platen  116  is improved due to the inner circular inner wall  162  which is adjacent the outer edge of the platen  116 . The inner wall  162  locates between the edge of the paten and the bristles  182  of the brush ring  132 . The inner wall  162  guides the moving air in a smooth manner and minimises the amount of contact between the moving air and the bristles  182  of the brush ring  132 . If the moving air were to come into contact with the bristles  182 , the air flow would become non-uniform as its passes through the bristles  182 . Furthermore, the use of the inner wall  162  to separate the bristles  182  from the edge of the platen  116  minimises the amount of dust and debris that collects within the bristles  182 . 
     The cross-sectional area of the gap  260  between the inner wall  162  and the edge of the platen  116  (shown by the hatchings  262  in  FIG. 6B ) is the same as that of the cross-sectional area of the flexible pipe  128  which in turn is the same as that of the first passageway  154  way in the two poles  196 ,  198 . 
     Referring to  FIG. 19 , the second pole  198  extends into the mount section  136  of the rear housing  104 . A part  270  of the side wall first aluminium tube  206  of the second pole  198  has been removed to expose the surface of the second aluminium tube  208 . The control electronics  144  are mounted in a control module. Where the part  270  of the first aluminium tube has been removed, the control module  144  is mounted inside of the first aluminium tube  206  adjacent the second aluminium tube  208 . This enables heat generated by the electronic module  144  to be transferred to the second aluminium tube  208  which is a good heat conductor and transfer the heat away from the control module  144 . Furthermore, during the operation of the pole sander, air is drawn through the second aluminium tube  208  by a vacuum cleaner. The air flow acts to cool the second aluminium tube  208  which in turn acts to cool the electronic module  144 . 
     The control electronics  144  are connected directly to the motor  114  using a single electrical cable  146  which carries the wires use to provide the electrical current to the windings of the brushless motor  114 . One end of the cable  146  connects directly to the control electronics  144  via a soldering tag  272  which connects to electric interface  274 . The other end connects directly to the motor  114 . The cable  146  is continuous with no plugs or connectors being used so as avoid interfering with the signals generated by the control electronics  144  which are sent down the cable  146  to operate the motor  114 . A central section  276  of the cable  146  located inside of the two poles  196 ,  198  is helical to enable the length of the cable  146  in a direction parallel to the longitudinal axis of the poles  196 ,  198  to extend or reduce depending on the relative telescopic positions of the two poles  196 ,  198 . When the cable  146  exit the first pole  196  and pass across the pivot mechanism  110 , it locates against the side of flexible pipe  128  as shown in  FIG. 21 . In order to maintain the position of the cable  146  relative to the flexible pipe  128 , a tubular sheaf  278  surrounds both the cable  146  and the flexible pipe  128  as shown in  FIGS. 26 and 27 . 
     An extension tube  280  connects to the end of the second aluminium tube  208  of the second pole  198  which extends the first passageway  154  of the second pole  198  through the rear handle section  138  of the rear housing  104  and projects rearwardly of the handle section  138 . The extension tube  280  is made from electrically conductive material and is electrically connected to the second aluminium tube  208 . A vacuum nozzle  152  is releasably attachable to the end of the extension tube  280  via a clip  282 . The vacuum nozzle  152  is made from electrically conductive material and is electrically connected to the extension tube  280 . The clip  282  comprises a first part formed on the vacuum nozzle  152  and a second part formed on the end of the extension tube  280 . The first part comprises two pins  284 , each pin  284  being mounted on the end of a resiliently deformable leg  286 . The second part comprise two holes  288  formed through the side wall of the end of the extension tube  280  in corresponding locations to the pins  284 . To attach the vacuum nozzle  152 , the legs  286  are bent inwardly so that the pins  284  can slide inside of the end of the extension tube  280  as the vacuum nozzle  152  is slid into the extension tube  280 . When the pins  284  align with the holes  288 , the pins  284  are biased into the holes  288  by the resilient legs  286  bending back to their original position. Whilst the pins  284  are located in the holes  288 , the vacuum nozzle  152  remains attached to the extension tube  280 . To detach the vacuum nozzle  152  the pins  284  are pushed back into the apertures to disengage them from the holes  288 . The nozzle  152  is slid out of the extension tube  280 . The vacuum nozzle  152  can be attached to the hose of a vacuum cleaner. As the nozzle  152  can be easily attached and detached, a suitable design of nozzle  152  can be chosen depending on the type of vacuum cleaner utilised. Furthermore, if the nozzle  152  breaks it can be easily replaced. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.