Patent Application
20060230564
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'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.
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.
Referring to
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'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
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'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'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
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
Brake rod 102 is actuated by squeezing the brake grip 114 positioned at end 82 of inner tube 12. As shown in
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
Connecting rod 116 has a first end 132 that is coupled to grip 114 (
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
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 (
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.
