Pressure reduction indicator esp. for valve caps of vehicle tyres - has housing divided by membrane providing desired and actual pressure chambers with signal mask visible through window if pressure drops

摘要

The housing (1) is divided into two chambers (3,4) by a membrane (2). One chamber is exposed to a desired pressure and the other to the actual pressure being monitored. An opaque signal mask (7) has central sectors which spread to form a light path when the mask deforms as the membrane approaches a window (5) in the housing under reduced actual pressure. The membrane is preformed with a concave curvature towards the mask. A signal body (12) between and in contact with the membrane and mask translates membrane displacements into mask deformations and appears in the mask apertures. ADVANTAGE - Sensitivity of indicator is considerably increased and danger of irreversible overstressing of membrane eliminated.