复数： gearboxes

No. granddad didn 't do the gearbox .

我爷爷不是做变速箱的。

They have more oomph , and no need of a gearbox to deliver it .

它们动力更加强劲，而且不需要变速器来传动。

The wings are driven by a crankshaft that is connected to a gearbox .

机翼由连接着齿轮箱的机轴驱动。

Motor-driven thresher , marine gearbox , combine harvester .

机动脱粒机、船用齿轮箱、联合收割机。

This engine uses a gearbox to allow the fan at the front and the turbine at the back to run at different , but optimal speeds .

该引擎利用齿轮箱，令前端风扇和后端涡轮机能以各自不同但却最优的速度运行。