friction rounds

例句：

1. 1. The machine has a friction round that helps it run smoothly.
   这台机器有一个摩擦圈，帮助它运行顺畅。
2. 2. The friction round on the car's brake system is designed to minimize wear and tear.
   汽车刹车系统中的摩擦圈设计成最小化磨损。
3. 3.The engineer used a friction round to reduce the noise from the machinery.
   工程师使用了一个摩擦圈来减少机械的噪音。