gravity-feed lubrication

例句：

1. 1.The engine requires a constant supply of oil to maintain its efficiency.
   发动机需要持续供应的油来保持其效率。
2. 2.The machine is designed to operate smoothly with minimal friction due to its gravity-feed lubrication system.
   这台机器设计得可以平稳运行，几乎没有摩擦，因为它的重力供油润滑系统。
3. 3. The hydraulic pump uses gravity-feed lubrication to prevent wear and tear on moving parts.
   液压泵使用重力供油润滑来防止移动部件的磨损。