20、试述自阀运转位，单阀制动区的综合作用？
["\u7b54\uff1a\u5355\u9600\u8c03\u6574\u4f9b\u6c14\u9600\u53e3\u5f00\u542f\uff0c\u6392\u6c14\u9600\u53e3\u5173\u9600\uff0c\u603b\u98ce\u7f38\u5411\u5355\u72ec\u4f5c\u7528\u7ba1\u5145\u6c14\uff0c\u4f7f\u4f5c\u7528\u9600\u5448\u5236\u52a8\u4f4d\uff0c\u603b\u98ce\u7f38\u538b\u529b\u7a7a\u6c14\u7ecf\u4f5c\u7528\u9600\u5411\u5236\u52a8\u7f38\u5145\u6c14\uff0c\u673a\u8f66\u5355\u72ec\u5236\u52a8\uff0c\u5355\u9600\u7684\u8c03\u6574\u9600\u63a7\u5236\u5236\u52a8\u7f38\u538b\u529b\u6700\u9ad8\u4e0d\u8d85\u8fc7300kPa\u3002"]