change gear case meaning in Chinese

变速齿轮箱
变速箱

The combine harvester is overall 3 packets of period of efficacy are 1 year ; 3 packets of period of efficacy are main part 2 years , main part is to point to internal - combustion engine airframe , cylinder housing of casing of lid , flywheel , frame , gear - box , clutch , change gear case of machine , final drive to body
联合收割机整机三包有效期为1年；主要部件三包有效期为2年，主要部件是指内燃机机体、汽缸盖、飞轮、机架、变速箱箱体、离合器壳体、转向机、最终传动齿轮箱体。