底门是J11型敝车的重要部件之一(图1)。它在车底架中梁两旁,每台车共有十四个。底门板用5公厘厚CT—3号钢板压制而成,工作表面尺寸为1590×1380公厘,其上压有六根横凸起的筋,下面焊有两根了5××75×10公厘的加强角钢——端梁,有一根前梁和两根纵梁,它们都用5公厘厚之CT—3号钢板压制成“U”型与底门板焊接在一起,还有两个焊在底门板和前梁的用 Bottom door is one of the important parts of the J11-type car (Figure 1). It is in the car chassis on both sides of the beam, a total of 14 cars per car. The bottom door with 5 mm thick CT-3 steel pressed from the work surface size of 1590 × 1380 mm, the pressure on the six transverse raised ribs, the following welded two 5 × × 75 × 10 male PCT reinforcement angle - end beam, there is a front beam and two stringers, they are 5 cm thick CT-3 steel pressed into a “U” type and the bottom door welding together, there are two welding Use at the bottom door and front beam