external splines

例句：

1. 1. The machine has a mechanism that allows it to operate with external splines.
   这台机器有一个机制，允许它使用外部花键操作。
2. 2. The design of the gearbox incorporates external splines for improved efficiency.
   齿轮箱的设计包括外部花键，以提高效率。
3. 3. In this project, we need to ensure that all external splines are properly aligned and secured.
   在这个项目中，我们需要确保所有外部花键都正确对齐并固定好。