Patent ID: 7044249

Claim:
A connecting structure of front and rear parts of a frame of a cart, comprising a first transverse rod at a rear end of a front frame part, which has one front wheel fitted thereto; a first upright rod projecting upwards from a rear portion of the front frame part; the upright rod having an engaging hole on a top; a second transverse rod at a front end of a rear frame part, which has two rear wheels fitted thereto; a second upright rod projecting upwards from a front portion of the rear frame part; a plurality of trench-formed fitting portions formed in front of the second transverse rod of the rear frame part; a pivotal portion fixed on the rear frame part; the pivotal portion having a stopping section facing rearwards at a lower end thereof; a support rod pivoted to the pivotal portion; the support rod being capable of being moved to a substantially upright position where it touches the rearwards-facing stopping section of the pivotal portion; the rear frame part being capable of being held steady with the front end thereof being slightly higher than a rear end with help of the rear wheels and the support rod when the support rod is in the substantially upright position; a spring joined to the support rod and the pivotal portion at two ends thereof for biasing the support rod to a substantially laid-down position; a second fitting portion projecting from a front side of the second upright rod; and a locking unit disposed on a top of the second fitting portion; the locking unit including: (1) a sleeve secured on the top of the second fitting portion; (2) an engaging rod passed through the sleeve with an upper end thereof projecting up from an upper opening of the sleeve; the engaging rod having a lower end, and an annular protrusion near to the lower end; (3) a spring positioned on an upper side of the annular protrusion of the engaging rod for biasing the engaging rod downwards such that the lower end of the engaging rod projects down from the second fitting portion; thus allowing the front and the rear frame parts to be joined together with the first transverse rod being fitted in the trench-formed fitting portions, the upper end of the first upright rod being fitted in the second fitting portion of the rear frame part plus with the engaging rod of the locking unit being inserted in the engaging hole on the front frame part.