韦氏P4a空气分配阀是根据三种压力原理,即制动缸和列车管压力与工作风缸压力相平衡的作用设计的,英国韦司汀豪斯制动机工厂早在1960年就已开始制造了这种分配阀。其平膜板及各阀体间的垫是用尼龙增强橡胶制成的,坚实而不怕高的局部应力。阀体顶上的夹心或平面式结构作为其他重要性 Webster P4a air distribution valve is based on three principles of pressure, that is, the brake cylinder and train pressure and the work of the cylinder pressure balance of the role of design, the British Weiting Ting House brake plant as early as 1960 has begun This distribution valve is made. The flat diaphragm and the pad between the body is made of nylon reinforced rubber, solid and not afraid of high local stress. Of other importance is the sandwich or planar structure on top of the valve body