1)steering differential and brake group,转向差速器和制动器组件2)steering differential group,转向差速器组件3)differential steering brake,差速转向制动器4)steering brake group,转向制动器组件5)brake and differential drive group,制动器和差速器传动组件6)steering clutch and brake control group,转向离合器和制动器控制组件