Rail head side flaw detection undercarriage for welded joint weld joint of welded rail base steel rail

The invention discloses a rail head side flaw detection undercarriage for a welded joint weld joint of a welded rail base steel rail. The undercarriage comprises a D mounting bracket, a D cylinder arranged on the D mounting bracket and provided with a downward piston rod, a D movable bracket in transmission connection with the piston rod of the D cylinder, and three groups of D detection structures arranged on the D movable bracket, each group of D detection structure comprises two D probe installation supports which are located on the two sides of the steel rail and symmetrically arranged, and the three groups of D detection structures are internally provided with D probe installation supports with different heights. The undercarriage has the advantages that according to the scheme, flawdetection can be conducted on the rail head of the steel rail, it can be guaranteed that the relative positions of the probes and the rail head are kept stable through a mechanical structure, the flawdetection efficiency and