| 摘要 |
PROBLEM TO BE SOLVED: To provide a detection device which allows simple maintenance and installation, is inexpensive and enables an operator at a site to check residue of concrete by watching directly.SOLUTION: A detection device comprises: a tabular body 20 arranged within a concrete hopper 10; a mark member 22 arranged outside the concrete hopper 10; a connection member 23 connecting the tabular body 20 with the mark member 22 through an opening formed in the concrete hopper 10; and a masking member 24 arranged outside the concrete hopper 10 to mask the mark member 22. When concrete is present on the tabular body 20, concrete serves as a weight and pushes down the tabular body 20, and, at the same time, the mark member 22 is lifted and masked by the masking member 24. When concrete is removed from the tabular body 20, the mark member 22 moves downward and is exposed from the masking member 24. |
