US Patent 10457308 Cart

A cart includes a bottom frame having a first transverse frame member and a longitudinal frame member, first and second back wheels, a first front wheel, a carrier frame, a collapsing mechanism, and a folding mechanism. First and second back wheel holders pivotably connect the first and second back wheels to opposite ends of the first transverse frame member, respectively. A first slide block slides along the longitudinal frame member. First and second guide units connect the first slide block to the first and second back wheel holder. A connecting member connects the carrier frame to the first slide block. A first front wheel holder pivotably connects the first front wheel to the bottom frame. A third guide unit guides the first front wheel holder. A longitudinal connecting arm connects the first slide block to the third guide unit for the first front wheel holder.