Gravity tricycle

Claim 1

A gravity tricycle, comprising: a front frame including a front wheel, a handle, a brake and a speed change controller, a rear frame connected to a rear end of said front frame and including a rotary shaft, two rear wheels disposed at two ends of said rotary shaft and a speed change toothed disk, shifting of which is controlled by said speed change controller of said front frame; and a transmission chain driven by a power-saving drive device which is wound around said speed change toothed disk to drive said rotary shaft to rotate said two rear wheels for advancement; wherein said drive device includes first and second pedals, which have drive rods respectively connected to bottom edges thereof, each of said drive rods including a longitudinally extended first member having a front end thereof pivotally disposed on a pivot shaft at a bottom edge of a front end of said rear frame, each said drive rod including a second member having a first end coupled to a rear end of said first member and extending upwardly therefrom, said second member having a second end coupled to a respective one of said two pedals such that said two pedals move upward and downward with said pivot shaft as a fulcrum; a transmission shaft on said rear frame and having an intermediate section provided with two unidirectional flywheels corresponding to said first and second pedals such that said two flywheels rotatably drive said transmission shaft in only one direction, said transmission shaft being provided with a toothed disk on one side of one of said flywheels to drive said transmission chain; and first and second reciprocating chains having front ends respectively connected to said rear end of said first members of said drive rods and being wound past upper ends of said flywheels to extend rearwardly, said first and second reciprocating chains having respective rear portions coupled together with a connecting element that is wound around a rotary wheel to thereby establish a linked-up relationship between said pedals.