A method and apparatus for preventing the unexpected loss of heavy mining equipment by detecting the separation of heavy metal parts at an early stage in the separation process, and providing a warning signal in response to which the particular machine that is having the difficulty may then be shut down in a timely manner. The housing supports the hinge plates for pivoting motion relative to the housing to open and close ring members mounted thereon. Information related to printing of image data is transmitted to the destination detected from the image data. Alternatively, the main body is a flat tube. A measuring means serves to determine the time-dependent change in the most minute amount of liquid.