Children's physics small production power bridge elementary school science class lever fulcrum arm principle assembly toy

Bailey bridge, engineer Tang of Sheffield University, UK In order to solve the problem of army crossing the river during the Second World War, Donald Bailey quickly assembled the artificial temporary bridge with the pre-designed steel truss. The bridge is characterized by simple and stable structure, and the bridge dye can bear several times the pressure of the bridge material. The production of this paragraph is to connect the beam to the longitudinal beam, and then use four side dyes to lock