spur-gear speed reducer

例句：

1. 1. The engine needsa new spark plug and a new speedreducer to keep it running smoothly.
   发动机需要更换新的火花塞和减速器，以保持其平稳运行。
2. 2. The car's performance was greatly improved with the installationof the new speed reducer.
   安装新的减速器后，汽车的性能得到了极大的提升。
3. 3.The engineer replaced the old gear reducerwith a more efficient one to save fueland improve efficiency.
   工程师用一个更高效的齿轮减速器替换了旧的，以节省燃料并提高效率。