Jacking span-changing device of vehicle-mounted rail layer

The utility model relates to the field of track layer jacking span changing, in particular to an efficient low-cost vehicle-mounted track layer jacking span changing device which comprises a track flat car, a supporting frame and a hydraulic jacking device, and the track flat car comprises a car bottom plate and idler wheels arranged at the bottom of the car bottom plate; the bottom of the support frame is connected with the vehicle bottom plate; the hydraulic jacking device comprises a lifting oil cylinder, a lifting rod and a lifting bracket, the lifting oil cylinder is arranged in the middle of the supporting frame, the upper end and the lower end of the lifting oil cylinder are connected with the supporting frame through an upper fixing plate and a lower fixing plate respectively, the lifting rod is arranged in the lifting oil cylinder, and the top of the lifting rod is provided with the lifting bracket. Compared with the prior art, the rail laying machine has the advantages that the working efficiency of