Patent Publication Number: US-2016236699-A1

Title: Three-in-one convertible hand truck

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a hand truck, and more particularly to a convertible hand truck that is convertible to a two-wheeled hand-truck, a reclined load-assist cart and a four-wheeled platform cart. 
     2. Description of the Related Art 
     Hand trucks have been developed over the years to aid people in the movement and transportation of items that otherwise would be too heavy or unwieldy to move. The ease of use of hand trucks makes the hand truck an ideal tool for transporting heavy objects. The wide utilization of hand trucks has caused many manufacturers to research improvements in the design of the modem hand truck. Today, industrial quality hand trucks are produced that have frames made of sturdier, tougher materials to simplify transporting appliances that are too large for smaller sized hand trucks. Additionally, hand trucks have been developed that are convertible into a cart or into an inclined cart to simplify the carrying of some objects. Examples of such hand truck may be found in U.S. Pat. No. 8,100,430 or in U.S. Pat. No. 6,364,328, in which a multi-mode hand truck is convertible to assume a hand-truck mode, a reclined load-assist mode, and a push-cart mode. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a new style of convertible hand truck that can be easily converted from a two-wheeled hand truck to either a reclined load-assist cart or a four-wheeled platform cart in a quick manner. 
     Briefly described, the hand truck of this invention includes a primary frame, a secondary frame and a linkage member. The primary frame has a hook member on a top end thereof and a pair of wheels rotatably mounted on a lower end thereof. The secondary frame has at least one caster rotatably mounted thereon. The linkage member has one end pivotally joined to the primary frame, and the other end pivotally joined to a lower end of the secondary frame. In particular, the primary frame is movable into (a) a hand-truck position, generally parallel to the secondary frame, (b) a reclined-cart-position, generally positioned at a predetermined angle with respect to the secondary frame, and (c) a platform-cart position, generally perpendicular to the secondary frame. While the primary frame is in either one of the reclined-cart-position and the platform-cart position, the hook member of the primary frame secures the primary frame to the secondary frame, and the pair of wheels of the primary frame cooperates with the caster of the secondary frame to support the primary frame. 
     Preferably, the secondary frame may include an elongated frame body having a pair of spaced, longitudinally extending rails and a cross bar extending between the pair of rails. When the primary frame is in the reclined-cart-position, the hook member of the primary frame is engaged with the cross bar of the secondary frame, thereby securing the primary frame to the secondary frame in the reclined-cart-position. 
     The secondary frame may further include a pair of brackets arranged on inner, opposed sides of the pair of the rails and arranged in a line generally parallel to the cross bar such that when the primary frame is in the platform-cart-position, the hook member of the primary frame is held in position by the pair of brackets, thereby securing the primary frame to the secondary frame in the platform-cart-position. 
     The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a front perspective view of a convertible hand truck in accordance with the preferred embodiment of the present invention; 
         FIG. 1B  is a rear perspective view of the hand truck shown in  FIG. 1A ; 
         FIG. 2A  is a front perspective view of the hand truck shown in  FIG. 1A  in a reclined-cart position; 
         FIG. 2B  is a rear view of the hand truck shown in  FIG. 2A ; 
         FIG. 3A  is a perspective view of the hand truck shown in  FIG. 1A  in a platform-cart position; 
         FIG. 3B  is another perspective view of the hand truck shown in  FIG. 3A ; 
         FIG. 3C  is a partially perspective view of another hand truck with a pair of modified brackets for supporting a primary frame; 
         FIG. 3D  is a view similar to  FIG. 3C , illustrating that the primary frame is engaged with the modified brackets; 
         FIG. 4A  is a partial enlarged view of the hand truck shown in  FIG. 2A ; 
         FIG. 4B  is a cross section taken along the line IV-IV in  FIG. 4A ; 
         FIG. 5A  is a partial enlarged view of the hand truck shown in  FIG. 1B , taken from another angle, showing a frame locking mechanism of the hand truck in a locked position; 
         FIG. 5B  is a view similar to  FIG. 5A , showing the frame locking mechanism in an unlocking position; 
         FIG. 6A  is a partial enlarged view of the hand truck shown in  FIG. 1A , showing a toe locking mechanism of the hand truck in a locked position; 
         FIG. 6B  is a cross section taken along the line VI-VI in  FIG. 6A ; 
         FIG. 7A  is partial enlarged view of the hand truck shown in  FIG. 1A , taken from another angle, showing that a linkage locking mechanism of the hand truck is in a locking position. 
         FIG. 7B  is a view similar to  FIG. 7A , showing that the linkage locking mechanism is in a released position. 
         FIG. 8  is a side elevational view of the hand truck shown in  FIG. 1A  in an upright hand-truck position; 
         FIG. 9  is a side elevational view of the hand truck shown in  FIG. 1A  being in transition to a four-wheeled cart; 
         FIG. 10  is a side elevational view of the hand truck shown in  FIG. 1A , in a reclined cart position; 
         FIG. 11  is a side elevational view of the hand truck shown in  FIG. 1A  in a platform cart position; and 
         FIG. 12  is a view similar to  FIG. 11 , except that a toe plate extension of the hand truck is in a raised, extended position. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Referring to the drawings in detail, there is shown in  FIGS. 1-12  a preferred embodiment of a hand truck, generally designated  100  in accordance with a preferred embodiment of the invention. Generally speaking, the hand truck  100  is convertible from a two-wheeled hand truck (shown in  FIGS. 1A and 8 ) into either one of a reclined cart (shown in  FIGS. 2A and 10 ) and a platform cart (shown in  FIGS. 3A and 11 ). To this end, the hand truck  100  generally includes a primary frame  1 , a secondary frame  2  and a linkage member  3  between the primary frame  1  and the secondary frame  2 , as shown in  FIG. 1B or 2A . 
     Referring in  FIG. 1 , the primary frame  1  includes an elongated frame body  10 , a generally U-shaped head portion  11  extending from an upper end of the frame body  10 , a hook member  12  is provided on the head portion  11 , a pair of wheels  13 ,  14  rotatably mounted on a lower end of the frame body  10 , a toe plate shelf  15  secured onto the lower end of the frame body  10  opposite the pair of wheels  12 ,  13 , and a generally U-shaped toe plate extension  16  generally located proximate to the toe plate shelf  15 . As best seen in  FIG. 2A , the frame body  10  of the primary frame  1  has a pair of spaced, longitudinally extending rails  101 ,  102 , three cross bars  103 ,  104 ,  105  extending between the pair of rails  101 ,  102  and spaced from one another. The toe plate extension  16  is pivotable between a retracted position (as shown in  FIG. 2A or 11 ), generally parallel to the rails  101 ,  102 , and an extended position (as shown in  FIG. 12 ), generally perpendicular to the rails  101 ,  102 . 
     As best seen in  FIG. 1B or 2B , the secondary frame  2  includes an elongated frame body  20  having a pair of spaced, longitudinally extending rails  201 ,  202 . The secondary frame  2  further includes a pair of hand grips  21 ,  22  extending from an upper end of the pair of rails  201 ,  202 , a cross bar  23  extending between the pair of rails  201 ,  202 , a pair of casters  24 ,  25  rotatably mounted a lower end of the pair of rails  201 ,  202 , and a pair of fork-shaped brackets  26 ,  27  formed on inner, opposed sides of the pair of the rails  201 ,  202  and arranged in a line generally parallel to the cross bar  23 . 
     As shown in  FIG. 2A , the linkage member  3  has one end pivotally joined to the middle cross bar  104  of the frame body  10  of the primary frame  1 , and the other end pivotally joined to a lower end of the secondary frame  2 . 
     The primary frame  1  is capable of moving into (a). a first, hand-truck position, generally parallel to the secondary frame (as depicted in  FIGS. 1A, 1B and 8 ); (b). a second, reclined-cart-position, generally positioned at a predetermined angle with respect to the secondary frame  2  (as depicted in  FIGS. 2A, 2B and 10 ); and (c). a third, platform-cart position, generally perpendicular to the secondary frame  2  (as depicted in  FIGS. 3A, 3B, 11 and 12 ). While the primary frame  1  is in either one of the reclined-cart-position or the platform-cart-position, the pair of wheels  13 ,  14  of the primary frame  1  cooperates with the casters  24 ,  25  of the secondary frame  2  to support the primary frame  1 , as illustrated in  FIG. 2A or 3A . 
     Furthermore, while the primary frame  1  is in the reclined-cart-position, as shown in  FIG. 2A , the hook member  12  of the primary frame  1  is engaged with the cross bar  23  of the secondary frame  2 , thereby securing the primary frame  1  to the secondary frame  2  in the reclined-cart-position. Similarly, while the primary frame  1  is in the platform-cart position, as best seen in  FIG. 3B , the hook member  12  of the primary frame  1  is held in position by the pair of brackets  26 ,  27  of the secondary frame  2 , thereby securing the primary frame  1  to the secondary frame  2  in the platform-cart-position. 
     In the illustrated embodiment, the pair of brackets  26 ,  27  are shown mounted at the opposed sides of the pair of the rails  201 ,  202 . However, it will be appreciated that other pair of bracket configurations could be utilized. For example, the brackets  26   a,    27   a,  as shown in  FIGS. 3C and 3D , may be utilized to support not only the hook member  12  with their fork-shaped portions  261 ,  271  but also a modified head portion  11   a  of a primary frame  1   a  with their hook portions  262 ,  272  extending from the fork-shaped portions  261 ,  271  respectively. 
     Referring back to  FIGS. 2B and 3B , the hook member  12  of the primary frame  1  has a curved tongue portion  120  and a pair of enlarged shoulders  121 ,  122  extending from opposite sides of the tongue portion  120 . When the primary frame  1  is in the reclined-cart-position, as shown in  FIGS. 2A and 2B , the tongue portion  120  of the hook member  12  of the primary frame  1  is engaged with the cross bar  23  of the secondary frame  2 . When the primary frame  1  is in the platform-cart position, as shown in  FIGS. 3A and 3B , the pair of shoulders  121 ,  122  of the hook member  12  of the primary frame  1  is supported and positioned by the pair of brackets  26 ,  27  of the secondary frame  2 . 
     Referring back to  FIG. 1A , the hand truck  100  further includes from top to bottom a hook locking mechanism  4 , a frame locking mechanism  5 , a toe locking mechanism  6  and a linkage locking mechanism  7 . Briefly, the hook locking mechanism  4  is provided to lock the primary frame  1  in the reclined-cart-position, as depicted in  FIGS. 2A and 4A . The frame locking mechanism  5  and the linkage locking mechanism  7  together are provided to ensure that the secondary frame  2  will not undesirably departs from the primary frame  1  while the hand truck  100  serves as the upright two-wheeled hand truck, as shown in  FIG. 1B . As for the toe locking mechanism  6 , it is provided to lock the toe plate extension  16  in the retracted position, as best seen in FIGS. lA and  6 A. 
     As shown in  FIG. 4A , the hook locking mechanism  4  is disposed on the head portion  11  of the primary frame  1  and is operable to allow or disallow the hook member  12  to be disengaged from the cross bar  23  of the secondary frame  2 , thereby locking or unlocking the primary frame  1  in the reclined-cart-position. More specifically, the hook locking mechanism  4  includes a casing  40  and a spring-loaded bolt  41  extending through the casing  40  from front to rear. The spring-loaded bolt  41  is normally inserted in a positioning hole  230  defined in the cross bar  23  of the secondary frame  2  for locking the primary frame  1  in the reclined-cart-position. To release the primary frame  1  from the reclined-cart-position, the spring-loaded bolt  41  be pulled out with respect to the casing  40  to be withdrawn from the positioning hole  230  of the cross bar  23  of the secondary frame  2 . 
     Referring to  FIG. 1B , the frame locking mechanism  5  is disposed on the upper cross bar  103  of the frame body  10  of the primary frame  1  for locking the primary frame  1  and the secondary frame  2  together. More specifically, as shown in  FIG. 5A , the frame locking mechanism  5  includes a pivot bracket  50  and a latch arm  51  pivotably mounted on the pivot bracket  50 . While the primary frame  1  is in the hand-truck position, the cross bar  23  may be hooked on the latch arm  51  with the positioning hole  230 , as shown in  FIG. 5A . To release the cross bar  23 , the latch arm  51  may be pivoted down, as indicated by the arrow in  FIG. 5B , so that the upper portion of the secondary frame  2  may be detached from the primary frame  1 . 
     Referring to  FIG. 6A , the toe locking mechanism  6  disposed on the middle cross bar  104  of the frame body  10  of the primary frame  1  and is operable to lock or unlock the toe plate extension  16  in the retracted position. As shown in  FIG. 6B , the toe locking mechanism  6  includes a spring-loaded bolt  61  extending through the middle cross bar  104  of the frame body  10  of the primary frame  1  from top to bottom and is operable to either be inserted in or withdrawn from a positioning hole  160  defined in the toe plate extension  16  for locking or unlocking the toe plate extension  16  in the retracted position. 
     Referring to  FIG. 7A , the linkage locking mechanism  7  is at least partly disposed on the lower cross bar  105  of the frame body  10  of the primary frame  1  for locking primary frame  1  and the linkage member  3  together. More specifically, as best seen in  FIG. 7B , the linkage locking mechanism  7  includes a male snap member  71  disposed on the lower cross bar  105  of the primary frame  1 , and a female snap member  70  disposed on the linkage member  3  to be engaged with the male snap member  71 . 
       FIGS. 8-12  illustrates a process of converting the hand truck  100  (as shown in  FIG. 8 ) into a reclined cart (as shown in  FIG. 10 ), and to a platform cart (as shown in  FIG. 11 ), and finally to the platform cart with the toe plate extension  16  stand upright for shielding articles (not shown) to be carried thereon (as shown in  FIG. 12 ). 
     As shown in  FIG. 8 , the hand truck  100  serves as a two-wheeled hand truck. At this time, it is noted that the frame locking mechanism  5  and the linkage locking mechanism  7  are preferable to both be in a locking state in order to ensure that the secondary frame  2  is not movable with respect to the primary frame  1 . Thus, as shown in  FIG. 9 , the secondary frame  2  is firstly detached from the primary frame  1  by unlocking the frame locking mechanism  5  as well as the linkage locking mechanism  7 . Then, the head portion  11  of the primary frame  1  may be rested on the cross bar  23  of the secondary frame  2  by the hook member  12 , as shown in  FIG. 10 . Preferably, the spring-loaded bolt  41  of the hook locking mechanism  4  is operated to be inserted in the positioning hole  230  of the cross bar  23  to ensure that the head portion  11  of the primary frame  1  is locked onto the cross bar  23  of the secondary frame  2 , as illustrated in  FIG. 4B . Afterwards, the spring-loaded bolt  41  may be withdrawn from the positioning hole  230  of the cross bar  23  to release the primary frame  1  from the secondary frame  1 . Next, the head portion  11  of the primary frame  1  may be pivoted downward and finally rested on the pair of brackets  26 ,  27  of the secondary frame  2 , as shown in  FIGS. 11 and 3B . If necessary, the toe plate extension  16  may also be pivoted up, as shown in  FIG. 12 , to provide extra protection.