Abstract:
A table saw including a horizontally disposed table surface with an elongated blade slot, mounted beneath the table surface is a traversing mechanism comprising a carriage coupled to linear guide rails and linear actuator to movably advance and retreat the carriage supporting the blade in a traversing path generally parallel to the blade slot. A tilt plate pivotally mounted to the carriage supports a blade drive assembly for providing a means to rotate the blade and adjust the blade height. The saw blade protrudes through the elongated slot to cut a work-piece on the table surface whereby stationary and moving work-piece operations may be executed. A tilting mechanism, also supported by the carriage, having a linear actuator in a translating engagement with the tilt plate rotate the tilt plate about its pivot axis relative to the carriage to set the blade to the angle desired by the user for beveled cuts. Blade height, angle and traversing speed are electronically controlled and set by the user through a user interface panel.

Description:
BACKGROUND 
     Prior Art 
       [0001]    The following is a tabulation of some prior art that presently appears relevant: 
       U.S. Patents 
       [0002]      
         [0000]    
       
         
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 Kind 
                   
                   
               
               
                   
                 Patent Number 
                 Code 
                 Issue Date 
                 Patentee 
               
               
                   
                   
               
             
             
               
                   
                 3,344,819 
                 A 
                 1967 Oct. 3 
                 Mitchell 
               
               
                   
                 7,721,633 
                 B2 
                 2010 May 25 
                 Gaw 
               
               
                   
                 4,209,045 
                 A 
                 1981 Oct. 6 
                 Walker 
               
               
                   
                   
               
             
          
         
       
     
       Foreign Patent Documents 
       [0003]      
         [0000]    
       
         
               
               
               
               
             
           
               
                   
               
               
                   
                 Kind 
                   
                   
               
               
                 Foreign Doc. Nr. 
                 Code 
                 Pub. Dt 
                 App or Patentee 
               
               
                   
               
             
             
               
                 1116539 
                 A3 
                 2003 Nov. 12 
                 Sberveglieri 
               
               
                   
               
             
          
         
       
     
         [0004]    A table saw is a power tool commonly used to facilitate forming a work-piece to a desired shape. To shape or cut the work-piece, a circular saw blade exposed above the table surface is rotated at a fixed point while the work-piece is slid on the table surface towards the blade. All table saws present a safety concern because saw blades are inherently sharp by design and rotate at a high rate of speed. Accordingly, injury such as severed digits and deep lacerations can occur almost instantaneously. In response to the dangers inherent with an exposed blade moving at high speed, a number of safety systems have been developed. One such safety system is a blade guard. Blade guards movably enclose the saw blade, thereby providing a physical barrier that must be moved before the rotating blade is exposed. While blade guards are effective in preventing injuries they can be removed for better convenience of use or removed because the blade guard is not compatible for use with a particular shaping device. For example, a blade guard is typically not compatible with a dado blade and must typically be removed when performing non-through cuts. 
         [0005]    Table saw safety systems have also been developed which are intended to stop the blade when a user&#39;s hand or fingers touches the blade. This type of safety feature is commonly employed thru braking devices that are physically inserted into the teeth of the blade. Upon actuation of this type of braking device, however, the blade and breaking member are typically ruined and for each time the safety device is actuated, significant resources must be expended to replace the blade and the braking member. Moreover, if spare blade and braking member are not on hand, a user must travel to a store to obtain replacements. Another shortcoming of this type of safety device is that, without having to damage the blade and braking member, the user has no means of testing whether the electronic controls responsible for stopping the blade are properly functioning. Defects in manufacturing and quality control failures are always a possibility and in the event the electronic controls are defective, the user will have no way of knowing whether the safety feature is functioning. This could lead to a fake sense of security that might perpetuate increased risk taking on part of the user and thus, increase the risk of injury. A further disadvantage of such a system is that the shaping device must be toothed and the safety system is prone to actuate when the material being cut is damp or wet. As such, wet or damp materials must be dried first before cutting, otherwise the user risks the chance of the safety system actuating and causing the needles expense of replacing the blade and the braking member. Thus, while effective, this type of safety system can be expensive, inconvenient and uncertain. 
         [0006]    Other devices commonly called jigs have also been developed in a variety of configurations to again reduce the possibility of having a hand or finger contact the blade. The various jig configurations generally enhance the operator&#39;s safety by increasing the distance of the user&#39;s hand away from the blade while making a cut. Although the risk to the user is reduced, the user must still assume a considerable amount of risk, such as the slip of the hand while holding and sliding the jig in relative close proximity to the blade. Another shortcoming of such systems is that they are typically designed for a specific cut. For example, a tenoning jig is only useful for making tenons. Since table saws are commonly used to cut various materials in a variety of ways, the user will have to expend resources for each kind of cut that can be more safely accomplished by use of a jig. 
         [0007]    Table saws are also currently configured with manual blade height and angle mechanisms, where the operator must turn a handle to adjust the blade height or angle, also called bevel. Although the height and angle of the blade can be set by slowly turning the handle and carefully aligning needle and tick mark height and angle indicators, setting the height and angle of the blade by this method is prone to inaccuracies because needle and tick mark indicators are susceptible to being thrown out of calibration and because accuracy depends on the user&#39;s ability to align the needle and tick mark using the naked eye. To achieve blade height and angle precision, manual measurement of the blade height and angle with a machinist&#39;s rule and protractor is typically required. This process often necessitates touching and manually rotating the sharp blade to make an accurate measurement. Although the blade is not rotating at a high rate of speed, the sharp blade can still be a safety concern for the user who will have to physically contact the blade to make the necessary blade height or angle measurements. Moreover, while manually adjusting the blade height and angle in this manner is effective, it is inconvenient because the user must crouch at an awkward position to align his or her eyes to the measuring device and blade while turning the blade height or angle adjustment handle. 
         [0008]    Other saw designs such as radial arm saws and slide miter saws have also been developed to provide stationary cutting from above the working platform. However, the rip cut (longitudinal cuts) widths are limited by the blades range of motion and they do not provide moving work-piece cutting capabilities. Furthermore, because the blade is mounted above the working platform, the height of the material that can be cut is limited by the space between the working platform and the blade&#39;s supporting mechanism. 
         [0009]    In view of the foregoing, it would be advantageous to enhance user safety and convenience by providing the user with a means of making a cut without having the user physically hold and slide the work-piece and without the height limitations inherent in radial arm saw and slide miter saw designs. It would be advantageous to simply clamp the work-piece onto the table surface and have the blade traverse towards the work-piece to make the cut by the simple press of a user interface button or screen. In addition to the stationary work-piece cutting capability just described above, it would be advantageous to be able to also provide the user with a moving work-piece cutting capability. This can be especially useful when conducting rip cuts. For example, a user conducting rip cuts can set the blade in a stationary mode and slide the work-piece towards the blade, but before the user&#39;s hand approaches the blade at an unsafe distance, the user can clamp the work-piece, move his/her hands away, adjust the table saw setting via a user interface panel and traverse the blade to complete the cut. It would also be advantageous to adjust the height and angle of the table saw blade by simply entering the desired height and or angle into the user interface panel to automatically and precisely adjust the blade to the desired height or angle via an electronic controls. 
       SUMMARY 
       [0010]    In order to overcome the deficiencies noted above, the present table saw with an automated traversing mechanism has been devised. The object of the embodiment is to improve upon known prior art by enhancing user safety, convenience, and work-piece cutting capability by providing the user with an automated means of traversing the blade via electronic controls for conducting stationary work-piece operations as well as moving work-piece operations without the work-piece height limitations of radial and slide miter saw designs. It is also the object of the embodiment to provide the user a convenient means of accurately adjusting the height, angle, and traversing speed of the blade through electronic controls via a user interface panel. As will be more fully described herein, the present saw comprises a horizontally disposed working platform with an elongated blade slot coupled to a main frame and a support frame, a traversing mechanism comprising a carriage coupled to linear guide rails and movable along a traversing path parallel to the blade slot. The carriage mounted beneath the working platform is coupled to a saw blade that protrudes through the slot to cut work-pieces on the platform. Linear actuators operatively coupled to the carriage advance and retreat the carriage along the guide rails at a plurality of positions. Pivotally mounted to the carriage is a tilt plate that supports a blade drive assembly where the blade is mounted and provides a means to rotate the blade wheel and adjust the height of the blade wheel relative to the table surface. The table saw further includes a tilting mechanism used to rotate the tilt plate and the mounted blade drive assembly at an angle desired by the user. Whereby the tilting mechanism supported by the carriage contains a linear actuator in a translating engagement with the tilt plate rotate the tilt plate about its pivot axis relative to the carriage. 
     
    
     
       DRAWINGS 
       Figures 
         [0011]    The foregoing aspects and many of the attendant advantages of this invention will become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
           [0012]      FIG. 1  is an isometric view of a table saw with a traversing blade constructed in accordance with one embodiment of the present disclosure; 
           [0013]      FIG. 2  is an isometric view of one suitable embodiment of the traversing mechanism, blade driving mechanism, and tilting mechanism of the table saw shown in  FIG. 1 ; 
           [0014]      FIG. 3  is a perspective view of one suitable embodiment of a traversing mechanism of the table saw shown in  FIG. 1 ; 
           [0015]      FIG. 4  is a partial isometric view of one embodiment of the blade drive assembly incorporated in the traversing mechanism of the table saw shown in  FIG. 1 ; 
           [0016]      FIG. 5  is a so-called exploded view of the blade arm and counter arm of the blade drive assembly shown in  FIG. 4 ; 
           [0017]      FIG. 6A  is a partial side view of one suitable embodiment of the blade arm and counter arm configuration, wherein the blade wheel is in the lowered position; 
           [0018]      FIG. 6B  is a partial side view of one suitable embodiment of the blade arm and counter arm configuration, wherein the blade wheel is raised to its maximum height; 
           [0019]      FIG. 7  is a so-called exploded view of the tilt frame and its attached elements that supports the mounting of the blade driving mechanism and tilting mechanism; 
           [0020]      FIG. 8A  is a partial perspective view of the tilting mechanism of the table saw shown in  FIG. 1 , wherein the tilt frame is in its nominal operating position; 
           [0021]      FIG. 8B  is a partial perspective view of the tilting mechanism of the table saw shown in  FIG. 1 , wherein the tilt frame is in an angled position; 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0022]      FIG. 1  illustrates one suitable embodiment of a table saw  100  constructed in accordance with aspects of the present disclosure. The table saw  100  has a work-piece support platform  110 , a main frame assembly  111  adapted to support the work-piece support platform  110 , a plurality of support legs  112  adapted to support the main frame  111 , and a blade wheel  113 . The blade wheel  113  is translatable to a plurality of raised positions in the vertical direction relative to the work-piece support platform  110  and traversable to a plurality of positions in the horizontal direction generally parallel to the work-piece support platform  110  along a slotted hole  114 . A control panel  115  enables an operator to control the vertical, horizontal, and angular translations of the blade wheel  113  relative to the work-piece support platform  110 . The control panel  115  is mounted on the main frame assembly  111  and can easily be attached and detached, so that the user can operated the blade movements anywhere around the table saw  100 . 
         [0023]    To site some of the advantages of the table saw  100  compared to a typical table saw that has a blade wheel rotating in a substantially stationary axis in the horizontal direction, as an example, when cutting generally small work-pieces where there is limited work-piece body to firmly hold and slide the work-piece safely by hand towards the rotating blade wheel  113 , the user of the table saw  100  can secure the work-piece on the work-piece support platform  110  by any suitable means or using accessories that are typically available for table saws such as hold down clamps  119 , which can be anchored and positioned along track  117 . Once the work-piece is positioned and secured as desired by the user, the user can traverse the blade wheel  113  using the control panel  115  to make the desired cut. In this manner, a user can perform cuts on generally small work-pieces without bringing their hands in close proximity to the rotating blade wheel  113 . Thus, the risk of injury is greatly reduced. Another example is when the user is nearing the end of a cut where the user is running out of sufficient work-piece body to firmly hold and continue feeding the work-piece safely, once the work-piece is within the traversing path of the blade wheel  113 , the user can once again secure the work-piece as described above and finish the cut by traversing the blade wheel  113  with the control panel  115 . 
         [0024]    The components of the table saw  100  that drives the blade wheel  113  to rotate and provide the means to translate the blade wheel  113  in the horizontal, vertical, and angular directions are disposed under the work-piece support platform  110 . To that end, please refer now to  FIG. 2  where the table saw  100  is shown with the work-piece support platform  110  and support legs  112  removed. The table saw  100  comprises a traversing mechanism  200  for translating the blade wheel in the lateral direction  150 , a blade driving mechanism  300  used to rotate the blade wheel  113 , a height adjusting device  350  (see  FIG. 4 ) for vertically translating the blade wheel  113  relative to the work-piece support platform  110 , a tilt frame  400  for supporting various parts of the blade driving mechanism  300  and height adjusting device  350 , and a tilting mechanism  500  for angularly positioning the blade wheel  113  relative to the work-piece support platform  110 . 
         [0025]    Referring now to  FIG. 3 , the figure illustrates the assembly of the traversing mechanism  200  (blade driving mechanism  300 , tilt frame  400 , and tilting mechanism  500  are not shown for the purpose of clarity). The main frame assembly  111  is composed of longitudinal members  111   a ,  111   b  that extend in the longitudinal direction  151  and lateral members  111   c ,  111   d  that extend in the lateral direction  150 . The longitudinal members  111   a  and  111   b  are spaced apart in the lateral direction  150  and the lateral members  111   c  and  111   d  are spaced apart in the longitudinal direction  151 . The lateral members  111   c  and  111   d  are fixedly attached by fasteners, welding or any other suitable means to the longitudinal members  111   a  and  111   b.    
         [0026]    The main frame lateral members  111   c  and  111   d  form the bases of the linear guide rails  210  and  211  for the traversing mechanism  200 . The linear guide rails  210  and  211  are rigidly attached to the main frame lateral members  111   c  and  111   d , respectively, and are configured generally parallel to the lateral direction  150 . 
         [0027]    The traversing mechanism  200  further includes a carriage assembly  212  slidably coupled to the linear guide rails  210  and  211  via a plurality of linear bearings  214 , a traversing motor  215  mounted to a traversing motor mounting frame  217  that is fixedly attached to the main frame longitudinal member  111   a , a traversing threaded rod  218  coupled to a traversing motor output shaft  216  on one of its ends and coupled to a traversing hand wheel  219  on its other end, shaft mount bearings  220  and  221  for supporting the traversing threaded rod  218 , a vertical support plate  222  attached to a carriage extended member  213 , and a traversing nut  223  fastened to the vertical support plate  222  and threadably engaged with the traversing threaded rod  218 . 
         [0028]    The carriage assembly  212  is composed of a longitudinal member  212   c  and extended member  213  that extend in the longitudinal direction  151  and lateral members  212   a  and  212   b  that extend in the lateral direction  150 . The main frame assembly  111  and the carriage assembly  212  are configured and sized to allow the tilt frame  400  (see  FIG. 4 ) and its attached assemblies to translate laterally and angularly without coming into contact with the main frame assembly  111  in its predetermined range of motion. 
         [0029]    Also, as shown best in  FIG. 3 , the ends of the guide rails  210  and  211  terminates to a point before it reaches the main frame longitudinal members  111   a  and  111   b  to provide enough spacein between the ends of the guide rails  210 ,  211  and the main frame longitudinal members  111   a ,  111   b  to facilitate installation or replacement of linear bearings  214 . 
         [0030]    In operation, the traversing motor  215  rotates the traversing threaded rod  218 , which in turn, moves the traversing nut  223 . The traversing motor  215  is selectively reversible so that the traversing threaded rod  218  can be rotated in either direction, thereby allowing the traversing nut  223  to transmit an actuating force on the vertical support plate  222 , that is attached to the carriage extended member  213 , to advance and retreat the carriage assembly  212  to a plurality of positions along the linear guide rails  210  and  211 . Alternatively, the traversing hand wheel  219  can be used to rotate the traversing threaded rod  218  to move the carriage assembly  212 , as the user desires. The traversing threaded rod  218  and traversing nut  223  acts like a jack screw, thereby, when the traversing motor  215  is in stop, it holds the carriage assembly  212  firmly in position. 
         [0031]    The linear actuator for traversing the carriage assembly  212  is shown as a threaded rod linear actuator and a nut. While the linear actuator is shown as threaded rod linear actuator, it may be any type of closed length linear actuator that can be attached to frame assembly  111  at both ends and can allow the carriage assembly  212  to translate linearly, including, for example, nut and screw, acme threaded rod, linear ball screw, linear track, rack and pinion, or linear slide. The traversing mechanism  200  may include two linear actuators of the same type, or each actuator may be of a different type. 
         [0032]    Referring now to  FIG. 4 , to show the reader how the traversing mechanism  200  is integrated in a table saw, a compactly arranged blade driving mechanism  300  mounted on the carriage assembly  212  is shown. The blade driving mechanism  300  is mounted to the tilt frame  400  as seen from another direction. The blade driving mechanism  300  includes a blade driving motor  310  mounted to the tilt frame  400  via a blade drive motor mounting base  311 , a drive pulley  312  mounted to the blade driving motor output shaft, a blade arm  313  supporting a blade pulley  314 , a counter arm  315  supporting a counter pulley  316 , and a drive belt  317  wound around the drive pulley  312 , the blade pulley  314 , and the counter pulley  316 . 
         [0033]    The blade height adjusting device  350  is used to translate the blade wheel  113  from a stowed position to a plurality of raised positions relative to the work-piece support platform  110  (see  FIG. 1 ). The blade height adjusting device  350  includes a height adjusting motor  351 , an intermediate shaft  353  coupled to the height adjusting motor output shaft  352 , a worm  354  operatively coupled to the height adjusting motor output shaft  352  via the intermediate shaft  353 , a shaft mount  355  for supporting the intermediate shaft  353 , a shaft mount  356  integrated to the bracket  410  for supporting one end of the worm shaft  357 , and a worm gear  358  fixedly attached to the blade arm  313  and engaged with the worm  354 . 
         [0034]    Accordingly, the reader will see that the carriage assembly  212  is the framework that supports the tilt frame  400 , which the blade driving mechanism  300  and the height adjusting device  350  are mounted to. The tilt plate  400  is pivotably mounted to the carriage via pivot blocks  224  and  225  and pivot about an axis generally parallel to the guide rails  210  and  211 . 
         [0035]    In accordance with the aspects of the present disclosure, the blade arm  313  and counter arm  315  are configured to ensure a sufficient wrap-around frictional engagement of the drive belt  317  to the pulleys when adjusting the height of the blade wheel  113  between a raised position and a stowed position. To that end, please refer to  FIG. 5  where the configuration of the blade arm  313  and counter arm  315  will be described in greater detail. As best shown in  FIG. 5 , the blade arm  313  includes a blade shaft  319  rotationally coupled to the blade arm  313 . The blade pulley  314  is coupled to the non-threaded end of the blade shaft  319 . The blade shaft  319  includes a collar  320  integrated to the blade shaft  319  to axially retain the blade wheel  113  from moving in the longitudinal direction  153  and has a threaded end 321 sized to threadably receive a blade wheel nut (not shown) to retain the blade wheel  113  from moving in the longitudinal direction  151 . When the worm gear  358  is attached to the blade arm  313 , the hole  323  of the worm gear  358  coaxially aligns with the hole  324  of the blade arm  313 . The blade arm  313  and worm gear  358  are coaxially mounted to the axle  318  and pivot about an axis generally perpendicular to the face of the tilt frame  400 . 
         [0036]    The counter arm  315  includes a counter pulley shaft  325  rotationally coupled thereto and a counter pulley  316  is fastened to the counter arm shaft  325 . The counter arm  315  has a hole  326  sized to axially fit the axle  318  and cooperatively pivot with the blade arm  313 . 
         [0037]    The blade arm  313  has a lip  327  that extends from a vertical face of the blade arm  313 . The lip  327  is oriented in a generally diagonal direction. Similar to the blade arm  313 , the counter arm  315  also has a lip  328  and oriented in the same manner. The lip  327  and lip  328  face each other and are sized and spaced to receive springs  329  to bias the blade arm  313  and counter arm  315 , in an opposing manner, causing the blade arm  313  to apply a compressive force against the counter arm  315 . Each spring  329  is fastened to lip  327  on one end and fastened to lip  328  on its other end, preferably by fasteners. As shown best in  FIG. 4 , the blade arm  313  and counter arm  315  forms a generally L-shaped member, where each leg has generally the same length. The springs  329  provides the belt drive system with enhanced stabilization and tensioning by compensating for misalignment and belt lengthening. The blade arm  313  and counter arm configuration also facilitates the installation and removal of the drive belt  317  (see  FIG. 4 ) during assembly or servicing, where the user can push the counter arm  315  towards the blade arm  313  to loosen the wrap-around engagement of the drive belt  317  and thereby allow for installation or replacement. 
         [0038]    In operation, as depicted in  FIGS. 4-5 , the user employing the tool energizes the blade driving motor  310  via the control panel  115  (see  FIG. 1 ). As the blade driving motor  310  rotates the drive pulley  312 , the drive belt  317  causes the blade pulley  314  to rotate and thereby rotate the blade wheel  113  via the blade shaft  319 . In adjusting the height of the blade wheel  113 , the user energizes the height adjusting motor  351  via the control panel  115  (see  FIG. 1 ), which in turn, rotates the worm  354  via the intermediate shaft  353 . As the worm  354  rotates, the threads of the worm  354  engaged with the teeth of the worm gear  358  will cause the worm gear  358  to rotate. The height adjusting motor  351  is selectively reversible so that the worm  354  can be rotated in either direction. Since the worm gear  358  is fixedly attached to the blade arm  313 , the blade arm  313  will rotate in unison with the worm gear  358  and thereby raise or lower the blade wheel  113 , depending on the direction of rotation of the height adjusting motor  351 . 
         [0039]    With the blade driving motor  310  remaining substantially stationary relative to the tilt frame  400 , the blade arm  313  and counter arm  315  are configured to turn in unison such that, as shown in  FIG. 6A , when the blade wheel  113  is initially in the stowed position, when the user energizes the height adjusting motor  351  to raise the blade wheel  113 , the blade arm  313  will rotate in the counter clockwise direction causing the blade wheel  113  to rise. The upward swing motion of the blade arm  313  causes the blade pulley  314  to takes up additional slack in the drive belt  317  extending from the drive pulley  312  towards the blade pulley  314 . The counter arm  315  rotates to simultaneously counteract the effects of the blade pulley  314  displacement on the drive belt  317  by giving up slack in the drive belt  317  extending from the drive pulley  312  towards the counter pulley  316 . 
         [0040]    As shown in  FIG. 6B , the blade wheel  113  is raised to its maximum height. In lowering the blade wheel  113 , the user energizes the height adjusting motor  351  to rotate the blade arm  313  in the clockwise direction. The downward swing motion of the blade arm  313  causes the blade pulley  314  to give up slack in the drive belt  317  extending from the drive pulley  312  towards the blade pulley  314 . The counter arm  315  rotates to simultaneously counteract the effects of the blade pulley  314  displacement on the drive belt  317  by taking up additional slack in the drive belt  317  extending from the drive pulley  312  towards the counter pulley  316 . 
         [0041]    Referring now to  FIG. 7 , the tilt frame  400  and its attached elements supporting the blade drive assembly  300 , height adjusting device  350 , and tilting mechanism  500  will be described in detail. As best shown in  FIG. 7 , the axle  318  that supports the blade arm  313  and counter arm  315  (see  FIG. 5 ) is fixedly attached to the vertical face of the tilt frame  400  and has a generally horizontal axis perpendicular to the vertical face of the tilt frame  400 . A cover plate  411  is fastened to the tilt frame  400  via mounting brackets  410 ,  417  and has a hole  412  sized to fit the end of the axle  318  to provide support for the free end of the axle  318 . The tilt frame  400  further includes a height adjusting motor mounting base  413  fixedly attached to the tilt frame  400  for supporting the height adjusting motor  315 . A drive motor mounting base  311  for the blade driving motor  310  is adjustably attached to the tilt frame  400  by fasteners extending horizontally through vertical slots  414  and through plate holes  415 . The tilt frame  400  has a curved slotted hole  416  oversized to allow the blade shaft  319  (see  FIG. 5 ) to move in its predetermined range of motion without contacting the tilt frame  400 . 
         [0042]    A tilting nut coupling plate  510  is pivotally joined to the tilt plate  400  via pivot frames  513  and  514 . The pivot frame  513  and  514  have pivot holes  511  and  515 , respectively, and are sized to fit pins  512  that are fixedly attached to the coupling base plate  510 . The coupling base plate  510  is retained by the pivot frame  513  to the tilt frame  400  by fasteners. 
         [0043]    Still referring to the embodiment of  FIG. 7 , the figure also illustrates the manner in which the tilt frame  400  is mounted on the carriage assembly  212 . The tilt frame  400  further includes pins  418  and  419  that are rigidly attached to the top corners of the tilt frame  400 . The tilt frame  400  is pivotably mounted on the lower part of the pivot blocks  214 L and  215 L and retained by the upper part of the pivot blocks  214 U and  215 U, respectively. 
         [0044]    Referring now to  FIGS. 8A and 8B , the tilting mechanism  500  is shown. The tilting mechanism  500  includes a tilting motor  516 , a tilting motor mounting plate  517  rigidly attached to the vertical support plate  222 , an intermediate shaft  518  coupled to a output shaft  519  of the tilting motor  516 , shaft support mounts  520  for supporting the intermediate shaft  518 , a universal joint  521  coupling the intermediate shaft  518  and a tilting threaded rod  522 , and a tilting nut  523  fastened to tilting nut coupling plate  510  and threadbly engaged with the tilting threaded rod  522 . The tilting mechanism  500  is used to tilt the tilt frame  400  between a nominal operating position, where the tilt plate is generally parallel to the vertical direction  154 , shown in  FIG. 8A , and at least a forty five degree position away from its nominal operating position, shown in  FIG. 8B . 
         [0045]    In operation, the tilting motor  516  rotates the tilting threaded rod  522 , which in turn, translates the tilting nut  523  along the axis of the tilting threaded rod  522 . The tilting motor  516  is selectively reversible so that the tilting threaded rod  522  can be rotated in either direction. The tilting nut  523  is coupled to the tilting nut coupling plate  510 , which is pivotally mounted to the tilt frame  400 . When the tilting threaded rod  522  rotates, the tilting nut  523  applies a push or a pull on the tilt frame  400  to rotate about its pivot axis, depending on the direction of rotation of the tilting motor  516 . 
         [0046]    The universal joint  521  and the tilting nut coupling plate  510  are configured to allow the tilting threaded rod  522  axis to gradually incline as the tilt frame  400  rotates away from it nominal operating position and to gradually recline as the tilt frame  400  rotates towards its nominal operating position. The tilting threaded rod  522  and tilting nut  523  acts like a jack screw; so when the tiling motor  516  is in stop, it holds the tilt frame  400  firmly in position. 
         [0047]    With respect to the above description, before explaining at least one preferred embodiment of the herein disclosed invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangement of the components in the following description or illustrated in the drawings. The invention herein described is capable of other embodiments and of being practiced and carried out in various ways which will be obvious to those skilled in the art. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. 
         [0048]    As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for designing of other structures, methods and systems for carrying out the several purposes of the present disclosed device. It is important, therefore, that the claims be regarded as including such equivalent construction and methodology insofar as they do not depart from the spirit and scope of the present invention. 
         [0049]    While all of the fundamental characteristics and features of the invention have been shown and described herein, with reference to particular embodiments thereof, a latitude of modification, various changes and substitutions are intended in the foregoing disclosure and it will be apparent that in some instances, some features of the invention may be employed without a corresponding use of other features without departing from the scope of the invention as set forth. It should also be understood that various substitutions, modifications, and variations may be made by those skilled in the art without departing from the spirit or scope of the invention.