speed-up gears

例句：

1. 1. The new car has a speed-up gears system that can increase its top speed by 20%.
   这款新车配备了一个可以将其最高速度提高20%的加速齿轮系统。
2. 2. The engineer designed the gears to be more efficient and reduce wear.
   工程师设计齿轮以提高效率并减少磨损。
3. 3.The old model had worn out gears that needed to be replaced.
   旧型号的齿轮磨损严重，需要更换。