The original locking device of Bast can efficiently prevent all kinds of vehicles from unexpected separation; its particular revolving and hook-type design can efficiently prevent vehicle from early departure and vehicle and goods space from unexpected separation; additionally, it can avoid the vehicle from overturn caused by the damage of fixed gear wheel or the inclination of rear box of vehicle. Flexible and reliable operation: the hook-type design allows to stretch 152mm or above, used for retaining the fixation at the place lower than the terminal end of vehicle. Even the gasbag-type vehicle, the powerful extension spring can move upwards and downwards along with the crash bar of vehicle, and then guarantee vehicle to be locked safely. Automatic positioning: it can be adjusted automatically according to the height of the crashworthy bar of vehicle and upon the backing force of vehicle; therefore it does not need to use external dynamic force.