free-piston machinery

例句：

1. 1.The free-piston machinery is a crucial component of the engine.
   自由活塞机械是发动机的关键部件。
2. 2. Free-piston machinery has been widely used in various industries.
   自由活塞机械在各个行业都有广泛应用。
3. 3.The engineers are working on developing new models of free-piston machinery.
   工程师们正在开发新型的自由活塞机械。