Abstract:
A hand truck for carrying and lifting a load comprising spaced vertical columns each having a channel. Rollers are captured in each of said channels that are capable of vertical movement along its respective channel. A first toe plate is affixed to said columns and adapted to extend horizontally during use. A second toe plate is attached to the rollers and adapted to move vertically along said columns between upper and lower positions. The first and second toe plates are in nesting relationship when the second toe plate is in its lower position.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 61/507,389, entitled “Hand Truck” filed Jul. 13, 2011, the disclosure of which incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     This application relates to a hand truck and more particularly to a hand truck for transporting and lifting a load. 
     BACKGROUND 
     The handling of material in tight spaces required, in many instances, the use of simple hand carts that could not lift, or heavier lifting systems that were expensive and difficult to maneuver. As a result, there is a need for a light and efficient hand truck that can provide for both the moving and lifting of materials that is light in weight, cost efficient and ergonomic. 
     SUMMARY 
     According to one aspect of the disclosure there is provided a hand truck for carrying and lifting a load comprising spaced vertical columns each having a channel. Rollers are captured in each of said channels that are capable of vertical movement along its respective channel. A first toe plate is affixed to said columns and adapted to extend horizontally during use. A second toe plate is attached to the rollers and adapted to move vertically along the columns between upper and lower positions; the first and second toe plates are in nesting relationship when the second toe plate is in its lower position. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a perspective view of the hand truck with the inner toe plate in a raised position; 
         FIG. 2  is a perspective view showing the hand truck in a collapsed position; 
         FIG. 3  is a sectional view showing the relationship of the three columns, panels and trolley member; 
         FIG. 4  is a plan view and side view of the center toe plate; 
         FIG. 5  is a plan view and side view of the outer toe plate; 
         FIG. 6  is a side view showing the toe plates in the collapsed position; 
         FIG. 7  is a horizontal sectional view through one of the outside masts or column; 
         FIG. 8  is an isometric exploded view of the split nut assembly; 
         FIG. 9  is an isometric view of the split nut assembly showing it in assembled condition. 
         FIG. 10  is a view similar to  FIG. 8 , but showing an alternative configuration of the channels and rollers; 
         FIG. 11  is a perspective view of a second embodiment of a hand truck in a collapsed position; 
         FIG. 12  is a perspective view of the embodiment of  FIG. 11  showing the toe plates in the extended position and the handles raised. 
         FIG. 13  is an isometric exploded view showing how various components of the second embodiment fit together; 
         FIG. 14  and  FIG. 14A  are an isometric view and top view respectively of a lifting bracket; 
         FIG. 15  is an isometric view of the bottom toe plate of the second embodiment; 
         FIG. 16  is an isometric view of the upper toe plate of the second embodiment; 
         FIG. 17  is an isometric view of the toe plates attached to the hand truck and showing the upper toe plate in a raised position. 
         FIG. 17  A is an isometric view of the toe plates attached to the hand truck and showing the upper toe plate in its lower position nesting with the lower toe plate. 
         FIG. 18  is an isometric schematic view showing the electrical drive arrangement; and 
         FIG. 19  is a partial isometric view showing one of the wheels of the hand truck. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In general, the hand truck comprises three spaced vertical extending masts or columns  2 ,  4 ,  6  aligned in a row. The two outside columns  2  and  6  are mirror images of each other while the center column  4  is of a different structure. The panels  8  and  10  run the entire length of the columns  2 ,  4  and  6 . Two panels  8  and  10  are provided, one on each side of the center column  4  connected between the center column  4  and a respective outside column  2  or  6 . A top and bottom cross bracket  12  and  14  interconnects the three columns  2 ,  4  and  6 . Spaced wheels  16  are connected by suitable means to the bottom bracket  14  at the rear of the hand truck as shown. 
     The hand truck includes two toe plates, one nesting inside the other, providing an inner toe plate  18  and an outer toe plate  20 . When the plates are in the nested position with the inner toe plate  18  in its lower position, the upper surfaces of the two toe plates  18  and  20  are coplanar. The outside toe plate  20  is stationary during use to provide stability while lifting. The inner toe plate  18  provides a lifting platform and is moveable upwardly and downwardly in a vertical direction along the columns  2  and  6 . Both the inside  18  and outside  20  toe plates are pivotal upwardly into a collapsed position as shown in  FIG. 2  wherein they extend vertically parallel to the elongated columns  2 ,  4  and  6 . 
     A handle  22  is provided having two elongated vertical posts  24  that extend into the outer columns  2  and  6 . The handle  22  is vertically moveable between a raised position as shown In  FIG. 1  and a collapsed position as shown in  FIG. 2 . 
     More specifically, the outside columns  2  and  6  as shown in  FIG. 7  are elongated extrusions and are mirror images of each other. Each column  2  and  6  includes a general circular channel  26  at the rear for receiving the posts  24  of the handle  22 . A slot  28 , opening to the inside, is provided at the front portion of the columns  2  and  6  to receive the panels  8  or  10 . An open channel portion  30  positioned between the circular channel  26  and slot  28  is provided that opens to the inside to capture the rollers  32  of a trolley member  34  as shown in  FIG. 3 . This portion  30  has opposed convex walls  31  that mate with the concave surfaces  133  of the roller  32 . A channel  35  opening to the outside allows for rotation of the toe plates for storage. 
     An alternative arrangement for the channel portion  30  of the columns  2  and  6  containing the rollers  32  is shown in  FIG. 10 . In this case, each roller  32  has a concave surface  133  that has a greater diameter at its inside edge  134  than at its outside edge  136 . The opposed walls  131  of the channel portion  30  of each of the columns  2  and  6  are convex having a mating contour to mate with the outside surface of the roller  32 . 
     The top and bottom cross brackets  12  and  14  are drawn together and held against the ends of the columns  2  and  6  by tension rods  15  extending through bore  27  in each of the outside columns  2  and  6 . The rods  15  have threaded ends that extend through the top and bottom cross brackets  12  and  14  and are fastened in tension with suitable nuts. 
     As shown in  FIG. 3 , the center column  4  includes a center circular channel  36  having a forward facing slot  38  running the length thereof. Two projections  40  extend rearward toward the outside as shown and are provided with slots  42  to receive the edge portion of a respective panel  8  or  10 . As shown in  FIG. 3 , each panel  8  and  10  extends between the slot  42  in the center column  4  and the slot  28  in a respective outer column  2  or  6 . 
     A screw member  44 , driven by a suitable motor  145  is positioned for rotation in the center circular channel  26  in the center column  4 . A connector, shown in  FIGS. 8 and 9 , includes a split nut  46  positioned in the center circular channel  36  around the screw  44  Each half of the nut has a forward flange portion  47  that extends through the slot  38  and which is connected to the trolley member  34 . 
     Each half of the split nut  46  has a reduced diameter upper and lower portion  48 . A nut ring  50  is positioned around the reduced diameter portions  48  to hold the two halves of the split nut  46  together. A bolt  52  and nut  54  secure the two flange portions together as shown. The head of the bolt  52  and nut  54  are countersunk. The nut  46  has internal threads to mate with the threads on the screw shaft  44  so that rotation of the shaft  44  causes the nut  46  to ride up and down on the shaft  44 . 
     The trolley member  34  as shown in  FIG. 3  extends between the two outside columns  2  and  6  and includes a front portion  56  with a side flange  58  extending rearward from each end of the front portion  56  as shown in  FIG. 3 . Each flange  56 , has an upper roller  60  and lower roller  62  (as designated in  FIG. 6 ) attached thereto by a shaft  64 . The rollers  60  and  62  are contained within the inside open channel portion  30  of a respective one of the outside columns  2  and  6 . 
     The inner toe plate  18  includes a flat lifting platform  66  with spaced upstanding flanges  68  extending to the rear on either side thereof. The flanges  68  have a bore  70  there through adjacent their upper edge through which the shaft  64  of the upper rollers  60  of the trolley member  34  extend. With this arrangement, the inner toe plate  18  is attached to the trolley member  34  while being able to pivot upwardly around the roller shaft  64  into its collapsed position. Downward pivotal movement is limited by a notch  72  on the bottom of the flange  68  that engages the shaft  64  of the bottom rollers  62  of the trolley member  34  when the inner toe plate  18  is in its horizontal position. 
     The outer toe plate  70  as shown in  FIG. 6  is generally U-Shaped with a forward portion  74  and two legs  76  extending rearward from the sides of the forward portion  74 . The forward portion  74  has a planar upper surface that is coplanar with the upper surface of the inner toe plate  18  when the inner toe plate  18  is in its bottom position. The outer toe plate  70  surrounds the inner toe plate  18  on three sides when the inner toe plate  10  is in its bottom position so that the inner toe plate  18  is nested within the outer toe plate  70 . The forward edge  78  of the outer toe plate  70  is provided with an L-shaped cutout  80  as shown in  FIGS. 1 and 2 . This shape enables the outer toe plate  20  to grab the outside corner of a box to make it easier to scoop under the box. 
     Each leg  76  of the outer toe plate  20  has an upstanding flange  82  at its inner end which is pivotally attached to a respective outer column  2  or  6 . A suitable latch mechanism (not shown) latches the outer toe plate  20  in its horizontal position whereby the outer toe plate  20  serves to hold the columns in their upright vertical position and provides stability to the hand truck in the vertical position. Release of the latch mechanism allows the bottom toe plate to be folded upwardly into the vertical position as shown in  FIG. 2  for storage. 
     As shown in  FIG. 1 , the handle  22  includes a cross member  84  having legs  86  extending forwardly from each end thereof. Each leg  86  is connected to one of the posts  24  that extending vertically downwardly therefrom and which is received in the circular channel  26  in a respective outer column  2  and  6 . With this arrangement the handle  24  can be moved upward and downward between an upper position as shown in  FIG. 1  and a collapsed position as shown in  FIG. 2 . A suitable locking mechanism (not shown) may be provided to hold the handle  24  in its various positions. 
     The drive train includes the screw member  44  contained in the center column  4 . A cordless DC rechargeable 14.4 volt battery pack and a suitable motor  145  may be provided and can be mounted on the bottom cross bracket  14 . A suitable drive connection, including a gear box may be provided between the motor and screw member  44  to enable the motor to rotate the screw member  44  and move the two-piece nut  46  up and down along the screw member  44 . Various controls may also be included including an up/down button which, when depressed, will cause the screw to turn and raise or lower the inner toe plate  18  with the load. Upper and lower limit switches may be provided to shut off the motor when the extreme upper and lower positions of the inner toe plate  18  are contacted. 
     A suitable brake mechanism, such as shown in U.S. Pat. No. 7,712,682, issued May 11, 2010 to Burton et al., entitled Lifting Device and Method may be provided. The disclosure of this U.S. Pat. No. 7,712,682 is incorporated herein by reference in its entirety. 
     Preferably, the columns  2 ,  4  and  6  are each a unitary one-piece structure. The columns  2 ,  4  and  6  may be extrusions fabricated from aluminum. Other suitable material may be used such as glass, plastic or carbon fiber resin. The panels  8  and  10  may be sheet metal. The panels  8  and  10  may be provided with compartments or other structure to hold accessories such as screwdrivers or other tools. 
     A second embodiment of the hand truck is shown in  FIGS. 11 and 12 . In this embodiment an alternative handle arrangement is provided that comprises two independent handles  122  each having a post  124  mounted in a channel in one of the outside columns  102  or  106 . A handle portion  125  is attached to the distal end of each post  124  and extends perpendicular therefrom. Each handle  122  is vertically adjustable between a lower position as shown in  FIG. 11  and an upper position as shown in  FIG. 12 . Each handle  122  is rotatable about the axis of its post  124  as indicated in  FIG. 12 . Suitable locking mechanisms may be provided to lock each handle in its various positions. 
     With the alternative handle arrangement, the handles  122  can be set to multiple positions independently. The locking mechanism may include a detent button (not shown) that may be pushed and each handle may be adjusted vertically (up to 24 inches as an example) to a comfortable height for the operator. The adjustable vertical feature can be used when going up or down stairs or for transporting a tall load. Additionally, the handle portions  125  can be rotated and locked pointing away from each other for more torque and stability, or locked at 45 degrees back toward the operator for comfort when transporting loads long distances. The handle portions  125  may be locked pointing toward each other in the case only a single hand is available to grip the handle portions in the center of the hand truck to move the load by a single hand. 
     This embodiment may have three spaced columns  102 ,  104  and  106  similar to the previous embodiment. Top and bottom cross brackets  112  interconnect the three spaced columns  102 ,  104  and  106 . Spaced wheels  116  and  118  are connected to the bottom cross bracket to the rear of the hand truck. A suitable motor may be provided motorize the wheels  116  to provide a means for propelling the hand truck. Panels such as panels  8  and  10  shown in  FIGS. 1,2 and 3  may be provided in this embodiment, and the tension rods  15  may also be included. 
     As in the previous embodiment, the hand truck includes two toe plates, an upper toe plate  118  and a lower toe plate  120 . The lower toe plate  120  is stationary during use to provide stability while lifting. The upper toe plate  118  provides a lifting platform and is moveable upwardly and downwardly in a vertical direction along the columns  2  and  6 . Both the upper toe plate  118  and the lower toe plate  120  are pivotal upwardly into a collapsed position as shown in  FIG. 11  wherein they extend vertically parallel to the elongated columns  2 ,  4  and  6 . 
     As indicated in  FIG. 13 , the bottom toe plate  120  is attached to the bottom cross bracket  114  by pins and a lock mechanism so that it can be locked in an operational position extending from the columns as shown in  FIG. 12  or pivoted and locked in a storage position extending generally parallel to the columns as shown in  FIG. 11 . The upper toe plate  120  is attached to a lifting toe plate backplate  155  via a hinge with a pin and latch mechanism on the side to permit rotation and locking of the upper toe plate  120  in a storage position as shown in  FIG. 11or  in an operational position extending from the columns as shown in  FIG. 12 . 
     The lifting toe plate backplate  155  is rigidly attached to a yoke  156  to which the rollers  132  are secured. The rollers  132  are mounted in the outer columns  102  and  106  as shown in  FIG. 10 . The yoke  156  is attached to a lifting bracket  146  which in turn is attached to the lead screw nut  145 . 
     As shown in  FIGS. 14 and 14A , the lifting bracket  146  includes a plate portion  157  that is connected to the yoke  156  and two vertically spaced bosses  158  secured to the plate by a rearward extending flange  159 . Each boss  158  has a through bore  160  which slidably receives the lead screw  144 . The lead screw nut  145 , which is threaded on the lead screw  114 , is captured between the two bosses  158  so that rotation of the lead screw  144  causes the lead screw nut  145 , along with the lifting bracket  146 , yoke  156  and upper toe plate  118  to move vertically up and down along the columns  102  and  106 . 
     As shown in  FIG. 15  the bottom toe plate  120  is generally U-shaped with a forward portion  174  and two legs  176  extending rearward from the sides of the forward portion  174 . The forward edge  178  of the bottom toe plate  120  is provided with an L-shaped cutout  180 . 
     As shown in  FIG. 16 , the upper toe plate  118  includes a planar portion  182  having a front edge with an L-shaped cutout  184  to match the L-shaped cutout  180  of the bottom toe plate  120 . The forward end of the top surface of the planar portion is tapered downwardly and forwardly as indicated at  186 . Forwardly and downward tapering sides  188  extend upwardly at both sides of the planar portion  182 . 
     As shown particularly in  FIGS. 17, 17A , a side skirt  189  extends downward from the bottom of the planar portion at either side of the upper toe plate  118 . The side skirts  189  are spaced apart a distance such that when the upper toe plate  118  is in its lower position, the bottom toe plate  120  is nested between the side skirts  189  with the side skirts  189  overlapping the side edges of the bottom toe plate  120 . The forward end  186  of the upper toe plate  118  may extend forwardly beyond the forward edge of the bottom toe plate  120 . 
     The upper surface of the planar portion of the upper toe plate may be provided with downwardly and forwardly tapering wedges  190  as shown in  FIGS. 16 and 17, 17A  to assist in the scooping of a load. 
     The drive arrangement may include a motor  145  as shown in  FIG. 18  mounted on the lower cross bracket  114  by a motor mount  147 . The motor  145  is attached to a suitable gearbox  149  that is attached to a clutch  150 . The clutch  150  has a shaft protruding through the lower cross bracket  114  that is attached to a gear that is attached to another gear on the lead screw  144 . 
     A removable battery holder  151  is mounted on the upper cross bracket  112  and has mounted therein a rechargeable battery  153  adapted to be recharged by a plug-in battery charging station  155 . The battery  153  is wired to a potentiometer trigger  157 , an up/down toggle switch  159  and the motor  145 , with the wiring, where convenient, passing through the center column  104 . The battery  145  may be a rechargeable lithium 18v battery. 
     In operation, the operator would take the hand truck folded for storage and unlatch the bottom toe plate  120  and upper toe plate  118  from their folded position and rotate them outward until they are locked in their operable position, general perpendicular to the columns  102  and  106 . The removable battery  153  would be placed in its holder  151  and, while the up/down toggle switch  159  is set to down, would depress the trigger  157  to start the motor  145  and move the upper toe plate  118  down to its lowest position nesting over the bottom toe plate  120 . The operator would then move the hand truck into position using the wheels  116  and ram the tapered front edge of the upper toe plate  118  underneath the load. To lift the load, the operator would lock the wheels  116  in the “parked” mode and change the up/down toggle switch  159  to up. The operator would press the trigger  157  to raise the load until the desired height is reached or until the upper limit is reached and the clutch  150  makes a clicking sound and there is no more vertical movement. 
     As shown in  FIG. 19 , the wheels  116  may have tires provided with cogs  165  around their periphery. The cogs will grip the stair tread to assist the hand truck in climbing stairs. 
     An inertia brake (not shown) may be provided for catastrophic failure of the nut and lead screw connection. A three axis accelerometer may also be provided with appropriate circuitry to prevent lifting if tipping. 
     With the above described arrangement, a hand truck is provided that is easy to operate, relatively light in weight, cost efficient and ergonomic.