Patent Publication Number: US-7721377-B2

Title: Extendable handle for drywall tools

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to drywall tools for applying mastic and especially to extendable handles for use with drywall tools. 
     Drywall tools, such as flat finishing tools for applying mastic to drywall joints, are typically provided with extendable handles that permit the user to comfortably reach areas of the drywall near the floor or ceiling. Such handles comprise an inner tube that telescopes within an outer tube to change the length of the handle. The tubes may be reversibly locked together relative to each other to fix a variable length of the handle during use. In conventional drywall tools, the tubes are locked together by a pin located on the outer tube that alternately engages one of a series of holes along the length of the inner tube. The pin is positioned at one end of a rocking lever that is spring-biased to engage the pin in one of the holes of the inner tube and lock the inner and outer tubes together. To change the length of the handle, the user applies pressure to the other end of the rocking lever against the spring-bias with his thumb to disengage the pin from the hole and allow the tubes to telescope freely. Once the handle has been extended or shortened to its desired length, the user releases the switch, allowing the pin to engage the appropriate hole on the inner tube and fix the length of the handle. 
     Because the rocking lever must be operated by the user&#39;s thumb, such conventional locking mechanisms can be awkward and tiring to use. Furthermore, as the user actuates the rocking lever, his hand or fingers may inadvertently become caught in the locking mechanism. To prevent such injury, the rocking lever is typically enclosed by walls positioned on either side of the locking mechanism. However, these walls make it difficult to access the locking mechanism for cleaning and repair. Thus, there is a need for a flat finishing tool with an extendable handle that is simpler and safer to operate, and that has a locking mechanism whose parts are readily accessible for cleaning and repair. 
     SUMMARY OF THE INVENTION 
     In accordance with an embodiment of the present invention, an extendable handle for a drywall tool comprises first and second members slidably coupled to each other. A locking element is positioned on a first side of the handle, for reversibly locking the first and second members in place relative to each other. A lever is positioned on a second side of the handle for actuating the locking element. In a preferred embodiment, the first member has at least one opening. A locking assembly is positioned on the second member for reversibly locking the first and second members in place relative to each other. The locking assembly comprises a base, a lever pivotally connected to the base, a pin and a yoke. The lever and the pin are spaced apart circumferentially on the handle and are connected by the yoke. The first and second members are reversibly locked together when the pin engages the opening in the first member. 
     In a further embodiment, the extendable handle includes a plate for mounting a drywall tool on the handle. The plate is rotatably connected to the second member and a brake is provided for controlling the rotation of the plate relative to the handle. A grip is positioned on the handle and coupled to the brake by a rod, and the movement of the grip actuates the brake. The rod has first and second ends, the first end coupled to the grip and the second end coupled to the brake. The distance between the grip and the second end of the rod is adjustable. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an extendable handle for a dry wall tool. 
         FIG. 2  is a detail side elevation view of the locking assembly of the handle of  FIG. 1 . 
         FIG. 3  is a detail bottom plan view of the locking assembly of the handle of  FIG. 1 . 
         FIG. 4  is an exploded detail view of the locking assembly and brake grip of the handle of  FIG. 1 . 
         FIG. 5  is a detail perspective view of the drywall tool attachment plate of the handle of  FIG. 1 . 
         FIG. 6  is a partial cut away detail perspective view of the drywall tool attachment plate and brake assembly of the handle of  FIG. 1 . 
         FIG. 7  is an exploded detail view of the drywall tool mounting plate and brake assembly of the handle of  FIG. 1 . 
         FIG. 8  is a detail perspective view of the brake grip of the handle of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , extendable handle  10  for a drywall tool is shown, comprising an outer tube  14  that is slidably coupled to an inner tube  12 , such that the inner tube telescopes within the outer tube. As best shown in  FIGS. 2 and 3 , inner tube  12  has a D-shaped cross-section with a flat face  16 . A series of holes  18  are formed in flat face  16  and disposed along the length of inner tube  12 . 
     The D-shape provides inner tube  12  with increased strength and resistance to bending, and prevents the inner tube from inadvertently twisting or rotating within outer tube  14 . In a preferred embodiment, the plane of flat face  16  is oriented generally parallel to the direction of the bending forces experienced by handle  10  during use, such as the pressure applied to the handle by the user and the weight of the drywall tool. Where the drywall tool is a flat finishing tool that is used to apply mastic to a wall with a vertical motion, the plane of flat face  16  is oriented perpendicular to the floor. 
     The length of handle  10  is changed by telescoping inner tube  12  within outer tube  14  until the appropriate length is achieved and then reversibly locking the inner and outer tubes in place relative to each other to fix the length of the handle. As described in detail below, inner and outer tubes  12 ,  14  are locked together by a lever actuated lock. The lever and lock are spaced apart circumferentially on the handle, to reduce the chance that the user&#39;s hand or fingers may become caught in the mechanism of the lock or between the lever and a tube when the lever is operated. Although the locking mechanism described herein comprises a locking pin  28  that engages a corresponding opening  18 , other types of locks may be used. For example, inner and outer tubes  12 ,  14  may be reversibly locked together by a friction lock or ratcheting mechanism, as are well known in the art. 
     As shown in  FIGS. 2-4 , a locking assembly  20  is positioned at end  22  of outer tube  14 , that comprises a base  24 , a locking lever  26 , a locking pin  28  and yoke  30 . Base  24  encircles outer tube  14  and is attached to end  22  by screws  32 . Locking lever  26  has a generally elongated triangular shape with a narrow end  34  connected to base  24  by a pivot  36 , and a wide end  38  that provides a relatively broad surface for the user to manually operate the lever. Yoke  30  is connected to locking lever  26 , and extends at least partially around handle  10 . In a preferred embodiment, yoke  30  is generally U-shaped and extends around base  24 , such that ends  40   a ,  40   b  of yoke  28  are attached to either side of wide end  38  of locking lever  26 . In an alternative embodiment, locking lever  26  and locking pin  28  are connected at either end of yoke  30 . Locking pin  28  is connected to yoke  30 , and is spaced apart circumferentially from locking lever  26  on handle  10 . In a preferred embodiment, locking pin  28  is positioned on handle  10  diametrically opposite locking lever  26 . As best shown in  FIGS. 3 and 4 , the head  42  of locking pin  28  is provided with a groove  44  that is received in a slot  46  formed in the middle portion  48  of yoke  30 . 
     In the locked position, locking pin  28  is engaged in one of holes  18 , which prevents inner tube  12  from sliding relative to outer tube  14  and fixes the length of handle  10 . A portion  50  of base  24  extends longitudinally beyond end  22  of outer tube  12 , such that wide end  38  of locking lever  26 , locking pin  28  and yoke  30  overlap inner tube  12 . A spring  52  is positioned between base  24  and locking lever  26  to bias wide end  38  of the locking lever away from the base. The action of spring  52  causes wide end  38  to pull yoke  30  and bias locking pin  28  toward inner tube  12  and into engagement with one of holes  18 . To change the length of handle  10 , the user operates locking lever  26  by applying hand pressure to wide end  38  against the spring  52  bias, which causes yoke  30  to withdraw locking pin  28  from the locked position by disengaging the locking pin from hole  18 . The user then slides inner tube  12  relative to outer tube  14  until the desired length of handle  10  is achieved and locking pin  28  is aligned with the appropriate alternate hole  18 . Locking lever  28  is released to allow the bias of spring  52  to cause locking pin  28  to engage an alternate hole  18  and again reversibly lock inner tube  12  and outer tube  14  in position relative to each other. 
     To prevent the user&#39;s hand or fingers from being accidentally caught in the mechanism of locking assembly  20 , base  24  is provided with a slot  54  for receiving yoke  30 . Slot  54  is sized and shaped such that yoke  30  is recessed within the slot and does not extend radially beyond the outer surface  56  of base  24  during the operation of locking lever  26 . Because locking assembly  20  does not require any walls to protect the user from the locking mechanism, as in conventional extendable handles, locking assembly is readily accessible for cleaning and repair. In a preferred embodiment, locking pin  28  is positioned on handle  10  diametrically opposite from locking lever  26 , which further reduces the risk that the user&#39;s hand will become caught in the movement of locking pin  28  while operating locking lever  26 . In addition, the user may maintain his normal grip on handle  10  and apply pressure to locking lever  26  with his palm, which makes locking assembly  20  more comfortable to operate and permits the user to exert more force on the locking lever than conventional extendable handles that are thumb operated. 
     A plate  58  is provided for mounting a drywall tool, such as a head for dispensing mastic, to handle  10 . In the embodiment shown in  FIGS. 5-7 , plate  58  is adapted to connect to a flat finishing box (not shown), and is pivotally coupled to the end  60  of outer tube  14  by a pin  62 . As best shown in  FIG. 7 , end  60  of outer tube  14  has a U-shaped clamp  64  with sides  66 ,  68 . An opening  70  sized and shaped to receive pin  62 , is formed between sides  66 ,  68  at the inside top of the “U.” Clamp  64  fits between a pair of spaced apart flanges  72  extending outwardly from plate  58 . Flanges  72  have openings  74  that are sized and shaped to receive pin  62 . Plate  58  is coupled to clamp  64  by threading pin  62  through openings  74  in the plate and opening  70  in the clamp and then fixing pin  62  to plate  58  with screws  76 . Pin  62  rotates freely within opening  70  of clamp  64 , allowing plate  58  and the attached drywall tool to pivot relative to handle  10 . 
     A brake assembly is used to control the rotation and fix the angle of plate  58  relative to handle  10 . The brake assembly comprises a brake rod  102 , lever  104  and block  106 . Brake lever  104  has first and second ends  108 ,  110 . First end  108  is pivotally connected to brake rod  102  by a pin  111 . Second end  110  is inserted through an opening  78  in clamp  64 , and second end  110  has a foot  112  that fits within a notch  80  formed in side  68  of the clamp, as best shown in  FIG. 5 . Brake block  106  is attached to clamp  64 , and supports second end  110  of lever  104 . Retracting rod  102  causes lever  104  to pivot against block  106  such that foot  112  exerts pressure on side  68  of clamp  64  to squeeze side  68  toward side  66 . Squeezing sides  66 ,  68  of clamp  64  constricts opening  70  and causes the clamp to grip pin  62  and stop plate  58  from rotating relative to handle  10 . 
     Brake rod  102  is actuated by squeezing the brake grip  114  positioned at end  82  of inner tube  12 . As shown in  FIG. 1 , brake grip  114  and locking lever  26  are positioned 90° apart on the circumference of handle  10 . In a preferred embodiment, brake grip  114  is oriented on handle  10  such that the user does not have to rotate the position of his hand or release his hold on handle  10  to comfortably operate brake grip  114 . 
     Grip  114  is coupled to brake rod  102  by a connecting rod  116  that accommodates changes in the length of handle  10 . As best shown in  FIGS. 4 ,  6  and  7 , brake rod  102  and connecting rod  116  are held parallel to each other within inner and outer tubes  12 ,  14  by housings  118 ,  120  positioned at opposite ends  82 ,  84  of the inner tube. Brake rod  102  is threaded through openings  122 ,  124  in housing  120 . Connecting rod  116  is threaded through opening  126  in housing  120 , and is seated in slots  128 ,  130  in housings  118 ,  120 . Brake rod  102  and connecting rod  116  are free to slide relative to each other as inner tube  12  telescopes within outer tube  14 . 
     Connecting rod  116  has a first end  132  that is coupled to grip  114  ( FIG. 4 ) and a second end  134  that is coupled to brake rod  102  ( FIG. 7 ). First end  132  of connecting rod  116  terminates with a threaded link  144  that is pivotally connected to the main shaft  117  of connecting rod  16  by brackets  146 . As best shown in  FIGS. 4 and 8 , grip  114  is pivotally connected to end  82  of inner tube  12  by a pin  136 . Grip  114  includes a pivot  138  that is rotatably mounted in arms  140  that extend toward end  82 . Link  144  is received in an opening  142  in pivot  138 . An adjustment member, such as a nut  148  is mounted on threaded link  144  to retain link  144  in opening  142  and couple link  144  to pivot  138 , such that, when grip  114  is actuated by squeezing, arms  140  rotate away from end  82  of inner tube  12  and pull connecting rod  116  longitudinally toward end  82 . 
     The movement of connecting rod  116  causes brake rod  102  to retract and stop plate  58  from rotating relative to handle  10 , as described above. As shown in  FIGS. 6 and 7 , end  134  of connecting rod  116  is pivotally connected to the base  150  of a washer  152  by brackets  154 . Brake rod  102  is threaded through an opening  156  in washer  152 . When inner and outer tubes  12 ,  14  are telescoped, brake rod  102  slides freely within opening  156  of washer  152 . However, when connecting rod  116  is pulled by actuation of grip  114 , a spring  158  causes washer  152  to pivot at the end  134  of the connecting rod such that the edges of opening  156  contact brake rod  102 . The friction created by contact between washer  152  and brake rod  102  is sufficient to cause the brake rod to be pulled by the movement of connecting rod  116 , thereby actuating the brake assembly to hold plate  58 . 
     In a preferred embodiment, the distance between grip  114  and second end  134  of connecting rod  116  is adjustable, to ensure the proper operation of the brake assembly as the various parts of handle  10  loosen or become worn with use. Nut  148  may be rotated on threaded link  144  to pull connecting rod  116  longitudinally toward grip  114  ( FIG. 8 ) and reduce the distance between second end  134  of the connecting rod  116  and grip  114 . Nut  148  engages pivot  138  to prevent nut  148  from inadvertently rotating on link  144  and changing the distance between second end  134  of the connecting rod  116  and grip  114  during use. As best shown in  FIG. 4 , the inner end  160  of the nut  148  is scalloped to conform to the shape of pivot  138 , such that nut  148  cannot rotate freely on link  144  while the nut it is in contact with the pivot. A spring  162  biases nut  148  toward pivot  138  to ensure that end  160  remains in contact with the pivot during normal use. 
     In operation, the user mounts a drywall tool, such as a flat finishing tool for applying mastic to a wall, to plate  58  on extendable handle  10 . The user may then adjust the length of handle  10  to suit the task. For example, it may be useful to fully extend handle  10  to its greatest length to allow the user to reach the top and bottom of a wall in a single motion. The length of handle  10  is adjusted by applying hand pressure to locking lever  26  to disengage locking pin  28  from one of holes  18  along the length of inner tube  12 . Inner and outer tubes  12 ,  14  are then telescoped to the desired length and the user releases pressure on locking lever  26  to allow locking pin  28  to engage the appropriate hole  18  and lock the inner and outer tubes together. Locking pin  28  is biased to engage holes  18  by spring  52 . 
     As the user moves the drywall tool over the wall, plate  58  pivots on pin  62  to allow the tool to pivot at the end  60  of outer tube  14  and maintain contact with the surface of the wall. In some cases the user may wish to stop the drywall tool from pivoting and fix the angle of plate  58  relative to handle  10 , such as when the flat finishing tool is removed from the wall after applying mastic. The user stops the rotation of plate  58  at the end  60  of outer tube  14  by squeezing brake grip  114 . Pin  62  pivots within a clamp  64  that is coupled to grip  114  by brake rod  102  and connecting rod  116 . Squeezing brake grip  114  pulls connecting rod  116  longitudinally toward end  82  of inner tube  12  and toward grip  114 . Connecting rod  116  is coupled to brake  102  and causes the brake rod to retract and squeeze clamp  64  to hold pin  62  and prevent plate  58  from rotating. To compensate for wear or loosening of the parts from repeated use, the distance between second end  134  of connecting rod  116  and grip  114  is adjustable by turning nut  148  on link  144 . 
     It will be apparent to those of skill in the art that modifications may be made without departing from the spirit and scope of the invention. Accordingly, it is not intended that the invention be limited except in view of the appended claims.