Middle spine type bus chassis frame

The utility model relates to a car frame of a car, which is composed of front end car frame, a back end car frame and a middle ridge beam supporting frame. The front end car frame and the back end car frame are side beam type. The middle ridge beam supporting frame comprises one-two longitudinal middle beams and at least four transverse branch beams, and the longitudinal middle beams and the transverse branch beams are fixedly connected. The longitudinal middle is supported and arranged on each transverse branch beam. At least two transverse branch beams are respectively transversely supported and arranged on two longitudinal beams of the front end and the back end car frames and the transverse branch beams are fixedly connected with the longitudinal beams. When the longitudinal middle beams of the middle ridge beam supporting frame are provided with two, the longitudinal middle beams are mutually parallel between the two longitudinal middle beams and are fixedly connected a transverse beam. The outside width of the two longitudinal middle beams is smaller than the outside width of the longitudinal beams of the front end and the back end car frames. The utility model has the advantages of simple structure and easy fabrication, and sufficient space under a floor of a passenger car carriage can be obtained for placing larger luggages.