To automatically brake a track working truck when uncoupling cars.

This car coupler 44 is vertically install in either side in a back- and-forth directions of a track working truck 40 so as to freely swing and gang with a brake device 41. The car coupler 44 is coupled to an operation rod 43 swingably attached to either side in the back-and-forth direction of the track working truck 40 so as to in integrally move. The brake device 41 is provided so as to gang with the operation rod 43. The operation rod 43 brakes a wheel 3 while the operation rod 43 is not operated, and releases braking of the wheel 3 when the operation rod 43 is operated. The car coupler 44 adds energizing force on the brake device 41 to brake the wheel 3 when swinging toward a lower position than a generally horizontal position, and loses the energizing force on the brake device 41 to release braking of the wheel 3 at the generally horizontal position.