ineffective part meaning in English

失效器件

This device takes rubber ( plastic cement ) as substitute for metal bumper , inside it an inflated tyre is set , ineffective part joining front of supporting frame and bumper is removed , and replaced by metal connecting bar , bar front is fixed unto bumper , and bar ' s rear connected with spring , spring ' s rear is fixed to a steel bowl firmly hugging closely an inflated rubber ball ( two ) , rear ball is closely hugged by another steel bowl at front of another spring , and another rubber ball placed at spring ' s rear
该装置由橡胶（塑胶）代替金属保险杠，内置充气胎，去掉前端大梁与保险杠连接的无效部分，以金属连杠代替，连杠前端固定于保险杠上，后端连接弹簧，弹簧的后端固定一钢碗紧贴充气皮球（两个），后皮球与另一弹簧的前端钢碗紧贴，另一弹簧的后端再放置一充气皮球。