Impact detection device for a system for locking the kingpin of a semitrailer on a railway unit

A railway unit on which a semi-trailer is intended to be loaded, which includes a system for locking a kingpin of said semi-trailer comprising a receiving structure provided to receive said kingpin, and which includes a general pipe for supplying fluid supplying and commanding in particular brakes of the railway unit, the railway unit further including an impact detection device comprising the following:

• a rigid connecting piece connected to the receiving structure, impacts experienced by the receiving structure being transmitted to said rigid connecting piece;
• at least one connecting shaft by which the rigid connecting piece is connected to the railway unit, this connecting shaft being mounted on the railway unit, pivotally received in an oblong provided in the rigid connecting piece and able to move in the oblong over a limited travel D provided on each side in the oblong;
• at least one shear pin inserted through the connecting shaft and the oblong that prevents the connecting shaft from moving in the oblong, this shear pin being provided to break in case of impact exceeding a certain threshold and then allowing the connecting shaft to move in the oblong;
• at least one bypass pipe mounted as a bypass on the general pipe of the railway unit, this bypass pipe being secured to the rigid connecting piece;
• at least one cutoff tool secured to the railway unit, which cuts off a part of the bypass pipe when the shear pin is broken and the connecting shaft is moving in the oblong associated with the connecting shaft.