Slide-folding handcart with back door

A slide-folding handcart with a back door, comprising:

• a frame assembly, wherein the frame assembly comprises a front bracket, a rear bracket, a chassis and two side brackets;
• the rear bracket comprises two rear vertical tubes, two rear fixing bases, a rear horizontal tube, a fence frame and two connecting belts;
• wherein two ends of the rear horizontal tube are fixed to lower ends of the two rear vertical tubes respectively, two sides of a lower end of the fence frame are riveted to the two ends of the rear horizontal tube respectively, and two sides of an upper end of the fence frame are rotatably connected with upper ends of the rear vertical tubes through the connecting belts respectively;
• wherein a wheel is arranged at a bottom of each said rear vertical tube;
• wherein the front bracket comprises a rectangular frame consisting of two front vertical tubes, an upper horizontal tube and a lower horizontal tube, and two front fixing bases, each said front fixing base is mounted at a top of the corresponding front vertical tube, and wheels are arranged on two sides of the rectangular frame;
• wherein each said side bracket comprises at least one X-shaped cross tube and two sliders, and the two sliders are respectively disposed around the corresponding front vertical tube and the corresponding rear vertical tube;
• wherein upper and lower sides of a front end of each said side bracket are riveted to the corresponding front fixing base and the slider disposed around the corresponding front vertical tube respectively, and upper and lower sides of a rear end of each said side bracket are riveted to the corresponding rear fixing base and the slider disposed around the corresponding rear vertical tube respectively;
• and
• wherein the chassis comprises two symmetrically hinged underframes, and front and rear sides of the chassis are riveted to the lower horizontal tube and the rear horizontal tube respectively.