Braking distance overrun testing device on escalator or moving walk

The invention discloses a braking distance overrun testing device on an escalator or a moving walk. When a driving motor drives the escalator or the moving walk to run, a metal disc rotates along with a driving sprocket, teeth and tooth slots on the metal disc can be inducted by a proximity sensor, and the proximity sensor outputs a square waveform pulse when inducting one tooth and one adjacent tooth slot. A control module is communicated with the proximity sensor, once the escalator or the moving walk stops, the control module detects a stop signal, at the moment, the pulses output by the proximity sensor are counted, and as the quantity of the pulses of the sensor is proportional to the braking distance of the escalator or the moving walk, the braking distance can be indicated by means of counting the quantity of the pulses. The quantity of the pulses corresponding to the braking distance 1.2 times larger than a standard maximum specified value is used as a set value, if the quantity of the pulses counted by the control module is larger than the set value, the braking distance is 1.2 times larger than the standard maximum specified value, then the control module can prohibit next running of the escalator or the moving walk, overrun protection to the braking distance is realized, and life safety of passengers and maintenance personnel is ensured.