Abstract:
A work bench. The work bench includes a table top, a plurality of legs connected to the table top, and a leg length adjustment mechanism positioned on at least one of the plurality of legs. The leg length adjustment mechanism includes a threaded rod configured to rotate about a rod axis, and a leg adjustment member moveable between a first position where the leg adjustment member threadedly engages the threaded rod and a second position where the leg adjustment member is removed from the threaded rod. Rotation of the threaded rod about the rod axis results in axial movement of the threaded rod when the leg adjustment member is in the first position. The threaded rod is freely moveable along the rod axis when the leg adjustment member is in the second position.

Description:
FIELD 
       [0001]    This invention relates to work benches and particularly to height and level control mechanisms for work benches. 
       BACKGROUND  
       [0002]    Work benches are used for a variety of different applications, such as a platform to hold a power tool, e.g., a power saw. A work bench may be placed on an uneven or unlevel surface. For example, the work bench may be placed on a concrete floor that has a slight to moderate slope in addition to being uneven. Such a floor can cause a top surface of a standard work bench to be unlevel and may allow the work bench to rock on the uneven floor. Both rocking and unlevelness can result in poor quality on the job site in addition to substantial safety issues. For example, if a circular saw is mounted to the top surface of the work bench, and the work bench is placed on a sloped uneven surface, the sloped surface of the work bench can reduce cutting quality of the circular saw. 
         [0003]    While work benches are available with legs that offer small height adjustments, for example by way of leveling screws coupled to the bottom of the work bench legs, these work benches are not suitable for floor surfaces that are substantially uneven. In addition, these work benches are sometimes inconvenient to level. Furthermore, in situations where there are steps or severe slopes and the work bench spans over the steps or over the severe slope, a work bench equipped with small height adjustment capabilities is not suitable. 
       SUMMARY  
       [0004]    According to one embodiment of the present disclosure, there is provided a work bench. The work bench includes a table top, a plurality of legs connected to the table top, and a leg length adjustment mechanism positioned on at least one of the plurality of legs. The leg length adjustment mechanism includes a threaded rod configured to rotate about a rod axis. The leg adjustment member is moveable between a first position where the leg adjustment member threadedly engages the threaded rod and a second position where the leg adjustment member is removed from the threaded rod. Rotation of the threaded rod about the rod axis results in axial movement of the threaded rod when the leg adjustment member is in the first position. The threaded rod is freely moveable along the rod axis when the leg adjustment member is in the second position. 
         [0005]    According to another embodiment of the present disclosure, there is provided an adjustable table leg. The adjustable table leg includes a proximal leg portion defining a bore segment extending axially therewith, a threaded rod extending into the bore segment, a coarse adjustment mechanism, and a fine adjustment assembly. The coarse adjustment mechanism is connected to the proximal leg portion. The coarse adjustment mechanism includes a body with a passage through which the threaded rod extends, and a stop member moveable between a release position and a lock position. The stop member is spaced apart from the threaded rod in the release position and is in contact with the threaded rod in the lock position. The fine adjustment assembly includes a distal leg portion and a knob which is rotatable to selectively move the distal leg portion axially in relation to the proximal leg portion. 
         [0006]    According to yet another embodiment of the present disclosure, there is provided a height adjustment apparatus for a table leg. The height adjustment apparatus includes a housing defining a central bore therein and fixedly coupled to a leg portion, a rod extending through the central bore of the housing, and a lever pivotable about a pivot moveable from a first position to a second position. The lever is in an interlocked interface with the rod when the lever is in the first position. The lever is released from the rod when the lever is in the second position. When the lever is in the first position the lever is configured to provide an angular orientation relative to the rod that generates a torque about the pivot, the torque generates a force that is applied by the lever to the rod in the interlocked interface, the force has a magnitude that corresponds to the weight applied to the leg portion. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  depicts a work bench equipped with a height adjustment assembly coupled to a leg; 
           [0008]      FIG. 2  depicts a perspective view of the height adjustment assembly depicted in  FIG. 1  with a cut out to reveal a structure for interfacing with the leg of the work bench; 
           [0009]      FIG. 3  depicts a cross sectional view of a course height adjustment portion of the height adjustment assembly shown in  FIG. 2 , depicted in a lock position; 
           [0010]      FIG. 3A  depicts a fragmentary cross sectional view of the course height adjustment portion of  FIG. 3 , depicted in a release position; and 
           [0011]      FIG. 4  depicts a work bench equipped with two height adjustment assemblies coupled to two legs. 
       
    
    
     DESCRIPTION  
       [0012]    For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and described in the following written specification. It is understood that no limitation to the scope of the invention is thereby intended. It is further understood that the present invention includes any alterations and modifications to the illustrated embodiments and includes further applications of the principles of the invention as would normally occur to one of ordinary skill in the art to which this invention pertains. 
         [0013]      FIG. 1  depicts a perspective view of a work bench  10  equipped with a height adjustment assembly  100 . The work bench  10  includes a top surface  12 , a plurality of legs  14  which are not equipped with the height adjustment assembly  100 , and one leg  16  that is equipped with the height adjustment assembly  100 . The work bench is optionally equipped with cross braces  18 . The legs  14  and  16  are connected to the top surface by fasteners, not shown. 
         [0014]    The height adjustment assembly  100  is connected to the end of a leg portion  17  ( FIG. 2 ) or the leg  16  and provides an extension of the leg  16 . The height adjustment assembly  100  provides the capability to make coarse and fine height adjustments to the leg  16 . As further described below, the height adjustment assembly  100  provides the capability to quickly finding a low spot on a floor surface on which the work bench  10  is resting. Such a low spot can result in the rocking of the work bench  10 . With the height adjustment assembly  100  coupled to a leg portion  17  of one leg  16 , the work bench  10  can also be automatically leveled, as described below, by activating the height adjustment assembly  100 . Auto-leveling of the work bench  10  is possible if the remaining three legs  14  all have the same height and the floor surface under these legs  14  is level. Fine adjustment of the height adjustment assembly  100  is also possible in order to fine tune the levelness of the workbench  10 . 
         [0015]      FIG. 2  depicts a perspective view of the height adjustment assembly  100 . The height adjustment assembly  100  includes a base  102 , a swivel member  104 , a fine tune dial  106 , a height adjustment member  108 , and a coarse adjustment assembly  200 . The height adjustment assembly  100  is fixedly connected to the leg portion  17  of the leg  16 . The interface between the coarse adjustment assembly  200  and the leg portion  17  can be permanent, e.g., by spot welding, or the interface can be provided in a modular manner. A leg extension member (not shown) can be added between the leg portion  17  and the coarse adjustment assembly  200 . In other embodiments, the height adjustment assembly  100  may be integrally formed as part of the leg portion  17 . A central hole/bore segment  26  in the leg  16  reciprocatingly receives the height adjustment member  108 . Therefore, the height adjustment member  108  can move up and down through the central hole  26  within the leg portion  17 . 
         [0016]    The base member  102  includes a flat bottom surface configured to engage a floor. A cavity is provided in the upper portion of the base member  102  with the swivel member  104  positioned in the cavity. The interface between the base member  102  and the swivel member  104  is in a form of a ball and socket configured to allow free movement of the ball within the socket. Accordingly, the swivel member  104  is free to pivot relative to the base member  102 . 
         [0017]    The fine tune dial  106  is fixedly coupled to the swivel member  104 . In the disclosed embodiment, the fine tune dial  106  is a disc-shaped member with a textured perimeter surface to facilitate gripping of the dial. In one form, the swivel member  104  and the fine tune dial  106  are integrally formed as a single piece. In another form the fine tune dial  106  is connected to the swivel member  104 , e.g., by spot welding. 
         [0018]    The height adjustment member  108  is fixedly connected to the fine tune dial  106 . In the embodiments of  FIGS. 1-4 , the height adjustment member  108  is provided as a threaded rod. A distal end of the threaded rod is fixedly coupled to the fine tune dial  106 . A proximal end of the threaded rod rotatably engages the coarse adjustment assembly  200 . In one form, the height adjustment member  108  and the fine tune dial  106  are integrally formed as a single piece. In another form the height adjustment member  108  is connected to the fine tune dial  106 , e.g., by spot welding or by using a locking nut (not shown), known in the art. Therefore, in the disclosed embodiments turning the fine tune dial  106  causes rotation of the height adjustment member  108 . The height adjustment member  108  may be a hollow or solid rod. The threads on the height adjustment member  108  may extend over the entire length of the height adjustment member or over a smaller portion of the height adjustment member. 
         [0019]      FIG. 3  depicts a cross sectional view of the coarse adjustment assembly  200 . The course adjustment assembly  200  includes a body/housing  202 , a lever  204 , and a spring  206 . The housing  202  is fixedly coupled to the leg portion  17 . The housing defines a center bore that extends completely through the housing and leads to the central hole  26  in the leg portion  17 . The height adjustment member  108  extends through the bore in the housing  202  and into the central hole  26  in the leg portion  17 . 
         [0020]    A first cavity  210  is formed in the housing  202 . The first cavity  210  is designed and dimensioned to receive a first end of the spring  206  such that the spring  206  is retained within the cavity  210 . 
         [0021]    The lever  204  is pivotably connected to the housing at pivot  212 . The pivot  212  includes a hole  216  and a pin  218 . The pin  218  passes through the hole  216  and couples with the housing  202  to thereby allow the pivot  212  to pivot about the pin  218 , as depicted by a curved double arrow BB in  FIG. 3 . Therefore, the lever  204  is a stop member pivotable between a lock position, depicted in  FIG. 3 , and a release position, depicted in  FIG. 3A . 
         [0022]    A second cavity  208  is formed in the lever  204  near a first end of the lever  204 . The second cavity  210  is designed and dimensioned to receive a second end of the spring  206  such that the spring  206  is retained within the cavity  208 . The spring  206  biases an upper portion of the lever  204  away from the housing, thus creating a spacing between the housing  202  and the lever  204 , as depicted by a double arrow AA in  FIG. 3 . 
         [0023]    The lever  204  includes a toothed or threaded interface  214  at a second end of the lever  204  opposite the first end. The threaded interface  214  is designed and dimensioned to provide an interlocked interface, e.g., a threaded engagement, with the threads on the height adjustment member  108 . Several factors including the angular orientation between the lever  204  and the height adjustment member  108 , the location of the pivot  212 , and the threaded engagement between the threaded interface  214  of the lever  204  and the threads of the height adjustment member  108  create a clockwise torque, indicated in  FIG. 3  as M, about the pivot  212 . 
         [0024]    While the bias force of the spring  206  adds to the clockwise torque M, the main portion of the torque is created by the angular relationship between the lever  204  and the height adjustment member  108 . Weights of objects that are placed on the top surface  12  of the work bench  10  as well as the weight of the work bench  10  itself create a downward force which is depicted as F 1  in  FIG. 3 . The force F 1  is balanced by an upward force F 2  that is exerted to the height adjustment member by the floor. The downward force F 1  tends to force the threads of the threaded interface  214  of the lever  204  into closer engagement with the threads of the height adjustment member  108 . This downward force F 1  also urges the lever  204  to pivot in a clockwise direction, thereby adding to the clockwise torque M. Therefore, a larger force F 2 , corresponding to a larger force F 1 , i.e., a heavier weight, creates a larger clockwise torque M. 
         [0025]    The relationship between weights of objects placed on the work bench and the clockwise torque M, provides a robust engagement between the threaded interface  214  and the threads on the height adjustment member  108 . This relationship reduces the potential for the lever  204  to snap back, which may release the height adjustment member  108 . 
         [0026]    The work bench  10  is suitable for placing or mounting a power tool, e.g., a ripsaw, on to the top surface  12 . In operation, an operator of the work bench  10  can grip the coarse adjustment assembly  200  and while holding the leg/course adjustment assembly  16 / 200  to overcome the biasing force of the spring  206  in order to close the gap, depicted as the double arrows AA in  FIG. 3 . The lever  204  pivots about the pivot  212  to disengage the threaded interface  214  from threads of the height adjustment member  108  in an arcuate movement, as depicted in  FIG. 3  by the double arrow BB. Once the threaded interface  214  disengages the threads of the height adjustment member  108 , the height adjustment member  108  (which is connected to the fine tune dial  106 , the swivel member  104 , and the base  102 ) is free to fall by the force of gravity until the base  102  makes contact with the floor. The base  102  swivels relative to the contour and the slope of the floor. The swiveling action of the base  102  increases the contact area between the bottom of the base  102  and the floor. 
         [0027]    After the base  102  makes contact with the floor, the operator can then release the lever  204 . The lever  204  returns to its resting position by the force of spring  206  by allowing the threaded interface  214  to engage with the threads of the height adjustment member  108 . 
         [0028]    If the legs  14  are resting on an even and a level floor while the leg  16  is rocking due to an unlevel or uneven floor, the course adjustment assembly  200  can automatically stabilize and level the table when the operator presses the lever  204 . The operator can then make fine tune adjustments by rotating the fine tune dial  106 . As discussed above, the height adjustment member  108  is connected to the fine tune dial  106 . Therefore, rotating the fine tune dial  106  rotates the height adjustment member  108 . Also, since the threaded interface  214  of the coarse adjustment assembly  200  is engaged with the threads of the height adjustment member  108 , rotating the height adjustment member  108  causes the height adjustment member  108  to axially move with respect to the coarse adjustment assembly  200 , thereby raising or lowering the leg  16 . 
         [0029]    While the height adjustment member  108  is described as a threaded rod, and the interface between the lever  204  and the height adjustment member  108  is described as a threaded engagement, the reader should appreciate that the interface can also be another form of an interlocked interface, e.g., a toothed engagement. In this alternative embodiment, a corresponding height adjustment member is a rod with a toothed interface along an exterior surface of the rod, while a lever which is part of a corresponding coarse adjustment assembly defines a toothed interface at one end of the lever, similar to the lever  204 . In this embodiment, rotating the height member would not result in advancement of the height adjustment member inside the coarse adjustment assembly. A fine tune assembly may be provided by combining a corresponding fine tune dial with a corresponding swivel member and a base. The fine tune assembly may have a threaded interface with the height adjustment member at a distal end of the height adjustment member, where rotating the fine tune dial would result in axial movement of the fine tune assembly with respect to the height adjustment member. 
         [0030]    It will be recognized that more than one height adjustment assembly  100  can be connected to the legs of the work bench  10  of  FIG. 1 . For example,  FIG. 4  depicts a work bench  50  with two height adjustment assemblies  100   1  and  100   2 . Each height adjustment assembly  100   1  and  100   2  connects to a corresponding leg  56 , while two legs  54  are unequipped with a height adjustment assembly. By adjusting the height adjustment assemblies  100   1  and  100   2 , the work bench  50  can be configured to interface with steps or with a floor that has a substantial slope. 
         [0031]    Also, while  FIG. 4  depicts two height adjustment assemblies  100   1  and  100   2  connected to two legs  16  that are on the same side of the work bench  50 , it is appreciated that the height adjustment assemblies  100   1  and  100   2  can be connected to legs that are diagonally across from each other. This alternative embodiment may be more suitable for placement of the work bench  50  over a floor that is grossly uneven. 
         [0032]    While the invention has been illustrated and described in detail in the drawings and foregoing description, the same should be considered as illustrative and not restrictive in character. It is understood that only the preferred embodiments have been presented and that all changes, modifications and further applications that come within the spirit of the invention are desired to be protected.