concave mounting bolt

• 凹板固定螺栓

concave mounting bolt的用法和样例：

例句

1. If table index shafts are loose, tighten mounting bolts.
   如果台面索引轴松动，拧紧固定螺栓。
2. One fixation bolt of undercarriage support in aircraft fractured after servicing a long time.
   某飞机起落架缓冲支柱固定螺栓长期使用后断裂。