| 摘要 |
A valve cap adapted to be screwed onto the valve of a pneumatic tire gives a pressure drop indication. To this end the valve cap comprises a deflectable diaphragm which separates the housing interior into a first chamber adjacent a transparent section of the closed housing end portion and a second chamber which is in communication with the tire interior through a port formed in a transverse housing wall and through the open tire valve. When the valve cap has been tightly screwed onto the tire valve and the tire valve has been opened, the desired tire pressure will be built up in both chambers. Upon closing of the second chamber a reference pressure corresponding to the desired tire pressure will prevail therein. Any reduction of the tire pressure relative to the reference pressure will cause the diaphragm to converge towards the transparent housing portion, thus serving as an indication. |
