1. 低速挡：常啮合 constant mesh | 低速挡 low gear | 高速挡 high gear

2. 加力挡：变速驱动桥 transaxle | 加力挡 low gear | 液力偶合器 hydraulic coupling

3. 低速档：low friction bearing 低摩擦轴承 | low gear 低速档 | low heat value 低发热值

4. 低束齿轮：low gear torque 低速传动扭矩 | low gear 低束齿轮 | low grade material 低级别材料

noun

1. the lowest forward gear ratio in the gear box of a motor vehicle
    used to start a car moving

    Synonym: first gearfirstlow