reciprocating weight

例句：

1. 1. The machine is designed to perform reciprocating motions.
   这台机器设计用来执行往复运动。
2. 2.The weight of the object is determined by its reciprocating movement.
   物体的重量由其往复运动决定。
3. 3. The balance of the system is maintained by the reciprocating weights.
   系统的平衡通过往复式重量来维持。