Patent ID: 8444173

Claim:
A foldable frame structure for baby trailer comprising: a bottom frame comprising two side bars horizontally arranged in parallel at two sides, a front bar and a rear bar connected between respective front and rear ends of said side bars, a channel-like lug affixed to a bottom side of one said side bar near a front end thereof and securing a trailer bar, said channel-like lug comprising a pair of pivot holes pivotally coupled to said trailer bar, a pair of front locating holes and a pair of rear locating holes, said trailer bar being pivotally coupled to said pivot holes and selectively lockable to said front locating holes or said rear locating holes between an extended position and a received position by a lock pin; first and second vertical side frames having a substantially U-shaped profile and two bottom ends respectively pivoted to said side bars of said bottom frame, said first vertical side frame comprising a lug disposed at a top side thereof and defining a locating groove, said second vertical side frame comprising a pivot holder disposed at a top side thereof, said first and second vertical side frames each being comprised of an arched top frame bar and two bottom frame bars, said arched top frame bar having two distal ends thereof respectively pivotally connected to respective top ends of said bottom frame bars with a respective pivot, each said bottom frame bar having a stop plate fixedly provided at the respective a top end thereof for stopping the associating arched top frame bar to limit the turning angle of the associating arched frame bar relative to said bottom frame bars; and a transverse top bar having one end thereof provided with a springy hook detachably fastened to the locating groove of the lug at said first vertical side frame and an opposite end thereof pivotally connected to the pivot holder at said second vertical side frame; wherein said front bar and said rear bar of said bottom frame are retractable, each comprising an outer tube having a locating hole near one end thereof, an inner tube having a locating hole near one end thereof and being axially slidably inserted into said outer tube, and lock means insertable through the locating hole of said inner tube and the locating hole of said outer tube to lock said inner tube and said outer tube in an extended position; the inner tube and outer tube of said rear bar each have one end thereof respectively axially slidably coupled to each other and an opposite end thereof terminating in a respective angled end piece, the angled end pieces of the inner tube and outer tube of said rear bar being respectively affixed to said side bars of said bottom frame to reinforce the structural strength of said side bars; said side bars of said bottom frame each have a pivot hole disposed above the angled end pieces of said rear bar of said bottom frame for receiving a respective pivot member to secure one respective wheel.