spare unit meaning in English

备份部件
备用部件
备用构件
备用设备

Compared with primal test stand , it spares units composed of large discrete components , lessens welded points . it greatly improves work reliability , test automation degree , test precision and efficiency . it is convenient for use , maintenance and repair
与原试验台比较，省去由大量分立元件组成的单元环节，减少焊接点，大大提高工作可靠性、检测自动化程度、检测精度和效率，使用、维护和修理方便。