Retractable shed frame of freight car

A retractable shed frame of a freight car comprises a shed frame, a transverse frame, a longitudinal frame, a main rod, a front door and two side doors. The retractable shed frame is characterized in that the transverse frame and the longitudinal frame are provided with sliding grooves matched with the pulleys of the shed frame, and positioning pieces are arranged at the top ends of the sliding grooves; a branch rod is arranged on the main rod and is provided with a plurality of lug holes; each of the front door and the two side doors is provided with a handle, a bolt block and a spring; the top end of the main rod is provided with through holes in positions connected with the transverse frame and the longitudinal frame, respectively; bearing pieces are arranged at both ends of the transverse frame and the longitudinal frame, and threaded holes are formed at the upper and lower ends of the bearing pieces in positions corresponding to the through holes and fixed by using screws. The three doors of the retracta