Moment limiting structure of folding arm type lorry-mounted crane

The invention relates to the technical field of cranes, in particular to a moment limiting structure of a folding arm type lorry-mounted crane, which comprises a rotary support device, a first hydraulic cylinder, a rotary support arm, a support arm, a protective device and a first angle sensor, the bottom end of the rotary supporting arm is rotationally connected into the upper end of the supporting arm, the first angle sensors are fixedly connected to the two sides of the upper end of the supporting arm, and the middles of the first angle sensors are connected with a driving clamping shaft at the bottom end of the rotary supporting arm. When the first hydraulic cylinder controls the rotating supporting arm to rotate in the supporting arm and the first angle sensor detects that the rotating supporting arm rotates to a large angle, the protection device operates at the moment, and real-time dynamic synchronous adaptive supporting protection can be conducted on the rotating supporting arm through the first angl