speed change gear

• 变速器

speed change gear的用法和样例：

例句

1. Planetary gear systems are also used in many automatic transmissions.
   行星齿轮组也同样用于许多汽车变速器中。
2. This means that in emergency situations or sudden deceleration, the transmission can quickly step down to LOW gear.
   这意味着在紧急情况或突然减速时变速器能够快速的降到低齿轮。