let-off gear

例句：

1. 1.The engineer had to let off some pressure before the machine could start.
   工程师在机器启动前必须释放一些压力。
2. 2.The car's brake system is designed with a let-off gear that can be easily adjusted.
   汽车的刹车系统设计有易于调整的释放装置。
3. 3. During the test run, the pilot had to let off the full amount of fuel in the tank to ensure smooth operation.
   在试运行期间，飞行员必须将油箱中的所有燃料完全释放以确保平稳运行。