Abstract:
A hand truck includes a frame, a telescopic handle pivotally connected with the frame, and a joint structure assembled between the frame and the handle. The frame is disposed with a collapsible wheel unit adjustable in position, and the handle and the frame can be bent and extended to a proper length and then fixed in position so that a user can push the hand truck with convenience. Further, the hand truck can be shaped alternately into a two-wheel vertical truck or a four-wheel platform hand truck.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to a hand truck, particularly to one having multi-function and able to be converted into a two-wheel hand truck or a four-wheel hand truck, able to be collapsed and convenient in use. 
   2. Description of the Prior Art 
   Hand trucks frequently used at present include two-wheel hand trucks and four-wheel hand trucks to be optionally chosen for use, but these two kinds of conventional hand trucks can be used for carrying and transporting goods only under a single form. Substantially, different kinds of goods have to be carried and transported by different kinds of hand trucks. For instance, some goods can be carried and transported comparatively conveniently and quickly, while others can be carried and transported by a conventional platform hand truck comparatively steadily. However, the conventional vertical or platform hand trucks is used to carry goods only in a single form, but cannot be changed in forms; therefore, if a user has to use the two conventional hand trucks alternately, he has to purchase two different kinds of hand trucks, thus increasing expense and taking too much space. A hand truck disclosed in a U.S. Pat. No. 6,938,905, which is designed by the inventor of this invention, can solve such a problem; nevertheless, this hand truck has something necessary to be improved, inclusive of disassembling and collapsing of its handle and wheels. 
   SUMMARY OF THE INVENTION 
   The objective of this invention is to offer a hand truck able to be collapsed and shaped alternately into a two-wheel or a four-wheel hand truck according to a user&#39;s needs, convenient in use. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
     This invention will be better understood by referring to the accompanying drawings, wherein: 
       FIG. 1  is an exploded perspective view of a hand truck in the present invention; 
       FIG. 2  is a perspective view of the hand truck in the present invention; 
       FIG. 3  is a perspective view of the hand truck in a using condition in the present invention; 
       FIG. 4  is a perspective view of the hand truck in another using condition in the present invention; 
       FIG. 5  is a cross-sectional view of a wheel unit fixed in position in the present invention; 
       FIG. 6  is another cross-sectional view of the wheel unit fixed in position in the present invention; 
       FIG. 7  is a perspective view of a handle in a stretched condition in the present invention; and 
       FIG. 8  is a perspective view of the hand truck in a collapsed condition in the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   A preferred embodiment of a hand truck in the present invention, as shown in  FIGS. 1 to 8 , includes a frame  1 , a handle  2 , a joint structure  3  and positioning members (N) as components combined together. 
   The frame  1  has its opposite frame rods  10  respectively assembled thereon with a wheel unit  11  able to be collapsed and respectively provided with a fitting member  12  and positioning holes  13 . Each wheel unit  11  is composed of a wheelbase  110 , a wheel  111  and an angle-adjusting device  112 , which consists of a pull member  1120 , a positioning member  1121 , a positioning plate  1122 , an elastic member  1123  and a cover  1124 . The positioning member  1121 , the positioning plate  1122  and the pull member  1120  are pressed by the elastic member  1123 , letting the positioning member  1121  inserted in the positioning hole  13  of the frame rod  10 , and the positioning plate  1122  and the positioning member  1121  are controlled by the pull member  1120 . When the pull member  1120  is pulled upward, the positioning plate  1122  and the positioning member  1121  will be actuated to move up, and the positioning member  1121  will be moved away from the positioning hole  13  of the frame rod  10 . At this time, the wheel unit  11  can be collapsed or stretched out easily. 
   The handle  2  assembled with the frame rods  10  of the frame  1  has its lower sides provided with two positioning slide slots  20  opposite to each other, two elastic members  21 , two slide-engage members  22 , a lateral positioning rod  23  and a lateral pull rod  24 . The two elastic members  21  are respectively fitted in the tube holes of the handle  2 , having one end resisting against the lateral positioning rod  23 . The two slide engage members  22  are respectively inserted in the inner diameters of the handle  2 , letting the outer end of the elastic member  21  push against one end of the slide-engage member  22 . Afterward, the slide-engage members  22  are pressed to have their insert holes  220  respectively aligned to the two positioning slide slots  20 , and then the lateral pull rod  24  has its opposite ends respectively inserted in both the position-slide slot  20  and the insert hole  220  and firmly positioned therein by a positioning member (N), letting the slide-engage members  22  controlled by the lateral pull rod  24  to slide in the inner diameters of the handle  2 . Further, the two slide-engage members  22  have their lower ends respectively secured with a positioning stud  221 , and the handle  2  has its upper end provided with a control member  25  and fitted therein with a telescopic U-shaped grip  26  bored with a plurality of positioning holes  260 , with the control member  25  adjusting the telescopic grip  26  in height and fixing it in position. The handle  2  further has its opposite lower ends respectively formed with a fitting portion  27 . 
   The joint structure  3  fitted between the frame rods  10  and the handle  2  is provided with two pivotal blocks  30  and two pivotal bases  31 . After pivotally combined together, the pivotal block  30  and the pivotal base  31  can be bent if necessary. The two pivotal blocks  30  respectively have one end fixed with a fitting member  32  to be fitted with the fitting member  12  of the two frame rods  10 , and the two pivotal bases  31  respectively have one end fixed with a fitting member  33  to be fitted with the fitting portion  27  of the handle  2 . Further, each pivotal block  30  has its circumferential surface bored with positioning holes  300 ,  301  and  302  at different angles for the positioning stud  221  of the slide-engage member  22  of the handle  2  to be inserted and positioned therein, thus enabling the handle  2  to be firmly positioned at different angles. The two wheel units  11  are respectively secured on the opposite frame rods  10  by means of positioning members (N). 
   In using, to shape the hand truck into a two-wheel hand truck, firstly, pull out a cargo fender from the frame  1  and position it at an angle of 90 degrees and then pull the pull members  1120  of the angle-adjusting devices  112  of the wheel unit  11  under the frame  1  to let the positioning members  1121  moved away from the positioning holes  13  of the frame rods  10 . Next, collapse inward the wheels  111  and release the pull member  1120  and at this time, the positioning member  1121  will be pressed by the elastic member  1123  to be inserted into the positioning hole  13  at another angle, thus finishing assembly of a two wheel hand truck, as shown in  FIG. 3 . 
   To shape the hand truck into a four-wheel hand truck, simply pull the pull members  1120  of the angle-adjusting devices  112  to let the positioning members  1121  moved away from the positioning holes  13  of the frame rods  10 , and after stretching out the wheels  111  and fixing them in position, release the pull member  1120 . At this time, the positioning members  1121  will be pressed by the elastic member  1123  to be inserted into the positioning hole  13  at another angle. Next, pull upward the pull rod  24  of the handle  2  to actuate the positioning studs  221  of the slide-engage members  22  to move away from the positioning holes  302  of the pivotal blocks  30  and, after bending the handle  2  upward for 90 degrees and positioning it perpendicular to the frame  1 , release the pull rod  24 . At this time, the slide-engage members  22  will be pressed downward by the elastic members  21  to have their positioning studs  221  respectively fitted in the positioning holes  301  of the pivotal blocks  30  to finish assembly of a four wheel hand truck, as shown in  FIG. 4 . 
   To collapse the hand truck, firstly, the wheel units  11  are collapsed inward to be positioned under the frame  1  by means of the angle-adjusting devices  112  and then the pull rod  24  of the handle  2  is pulled upward to force the positioning studs  221  of the slide-engage members  22  to move away from the positioning holes  301  of the pivotal block  30 . Next, the handle  2  is collapsed inward to be laid on the frame  1  and at this time, the slide-engage members  22  will be pressed down by the elastic members  21  to have their front positioning studs  221  respectively engaged in the positioning holes  300  of the pivotal blocks  30 , as shown in  FIG. 8 . Thus, the hand truck is collapsed not to take much space, and the frame  1  and the handle  2  can be stably positioned on the frame  1  by means of the joint structure  3 , convenient in operation. 
   As can be understood from the above description, this invention has the following advantages. 
   1. After the hand truck is collapsed, the handle  2  can be stably positioned on the frame  1  by mutual engagement of the positioning studs  221  of the slide-engage members  22  and the positioning holes  300  of the joint structure  3 . 
   2. The frame  1  and the handle  2  controlled by the joint structure  3  can be stably and conveniently adjusted in position as well as in angle. 
   3. The hand truck of this invention can be shaped alternately into a two-wheel vertical hand truck or a four-wheel platform hand truck for use according to a user&#39;s practical needs. 
   4. Both the wheels  111  and the handle  2  of the hand truck of this invention can be collapsed, facilitating transport and saving space. 
   5. The telescopic U-shaped grip  26  of the handle  2  can be adjusted in height according to a user&#39;s needs, conforming to ergonomics. 
   While the preferred embodiment of the invention has been described above, it will be recognized and understood that various modifications may be made therein and the appended claims are intended to cover all such modifications that may fall within the spirit and scope of the invention.