Derailing detection device for sampling machine

The embodiment of the invention provides a sampling machine derailment detection device, and relates to the field of pavement flatness detection. According to the sampling machine derailment detection device, a hub frame is arranged below a traveling crane, hubs are arranged at the two ends of the front face of the hub frame respectively, a first support is arranged on one side of the upper end of the hub frame in the advancing direction of the hubs in an extending mode, a proximity switch is arranged at the tail end of the first support, and a sliding cover capable of cleaning the surface of a steel rail is arranged above the steel rail. According to the derailment detection device for the sampling machine, the sliding cover can move along the surface of a steel rail while the sliding rod moves, impurities on the surface of the steel rail can be cleaned after the sliding cover moves, and the detection influence of the impurities on the proximity switch is prevented; at the moment, the gas in the pressurizing