PURPOSE: To monitor a minimum wall thickness that is functional and effective by installing a sensor having at least one heat resistant electricity transmission wire in a recess in surface of structure subject, and constituting the length of the sensor projective from the recess corresponding to a predetermined minimum wall thickness of the structure subject.
CONSTITUTION: As far as the thickness of skid material 1 is not smaller than the minimum wall thickness L, the sensor 4 does not make any response. The sensor 4 has a heat resistance because of its special structure to resist high temperature during the whole brake course that is relatively high temperature. When the skid 1 is scraped to the minimum wall thickness L, it goes worse in the continuous processes. At this time, at first, the outer conductor 18 of the transmission wire 5 is scraped, and the capacity of the transmission wire 5 is therewith changed, the capacity changing of the wire is evaluated by an arrangement 6, and at last the skid 1 is exchanged. When loss of the skid 1 goes on to such a state that the transmission wire 5 and insulation of the inner conductor 15 are nearly breakdown, a short circuit occurring at this time, insulation of the conductor 15 are also indicated in an apparatus 6.
FURIIDORITSUHI SHIYUAUERU
KURUTO KURAAMERU
THYSSEN INDUSTRIE