
344 LIGHT AND HEAVY VEHICLE TECHNOLOGY
Core This is a complete assembly comprising a screw-
in hollow plug with a plastics seal making an air-tight
contact with a seating in the valve body, and a spring-
loaded plunger with a synthetic rubber seal making an
air-tight contact against the underside of the hollow
plug (Figure 21.11). The spring-loaded plunger acts as
a check valve in that it is closed and held on to its
seating not only by its spring load but also by the
pressure of air it is retaining. It can thus admit air at a
higher pressure during inflation, and release air only
when one is either pressure checking or purposely
deflating th ...