Tunnel furnace ceiling height monitor.

摘要

A tunnel furnace height detector for detecting ceiling heights of a tunnel furnace comprises a plurality of detecting units (8) arranged on a trolley travelling in the tunnel furnace with their heights progressively lower by predetermined distances. Each of the detecting units comprises a support base (8) and a solid member pivotally connected to the support base automatically retunable from a pivotally moved position caused by an external force to an original position. The member has one end which contacts a lowered ceiling portion and its other end closes and opens a measuring circuit system.