The utility model discloses an air cushion car is high in mechanical strength, including base, box and top cap, wherein, the box passes through bolt fixed mounting on the base, the top cap passes through the connection piece to be fixed in the box upper end, the box is including stand, curb plate and the crossbeam of concatenation each other, the top cap is including top beam, curb girder, herringbone eaves and the apron of concatenation each other. The air cushion car is high in mechanical strength of above -mentioned structure can be with including the installation of large -scale switchgear, is adapted to that transformer substation (power plant) is newly -built, enlargement and improvement project, installs in open air and operation at the 12kV prepackage type switch box of frequency for 50Hz, 12kV electric pressure. The switch box adopts base, box and the split type modularized design of top cap, has compact structure, area is little, alternative is big, on -the -spot installation volume is little, the installation and debugging cycle lacks to and along with advantages such as load center removals.