engine crankcast

例句：

1. 1.The engine was crankcast from a single piece of metal.
   发动机是由一块金属锻造而成的。
2. 2. The crankcase is where the pistons move up and down.
   曲柄箱是活塞上下移动的地方。
3. 3.The crankshaft is responsible for turning the engine's wheels.
   曲柄轴负责转动发动机的轮子。