DETECTION STRUCTURE FOR ABNORMALITY OF TENSIONING APPARATUS FOR OVERHEAD WIRE

PROBLEM TO BE SOLVED: To obtain a detection structure by which whether the tension of an overhead wire is proper or not is always monitored, by which an abnormality can be detected at an early stage so as to take measures and which prevents the disconnection of the overhead wire by a method wherein a gas for a spring or a pressure is monitored and a change in the tension of the overhead wire is monitored. SOLUTION: When a moving cylinder 2 is pulled to the right side by an overhead wire L via a moving rod 3, a fixed rod 4 is going to rush further into a liquid chamber 2b, a gas chamber 2a is pressurized via a liquid, and proper tension is generated by a springy action due to a gas pressure against it. At this time, the tension of the overhead wire L has a constant relationship with the pressure of a gas sealed in the gas chamber 2a and of a liquid sealed in the liquid chamber 2b. P.V/T=constant. That is to say, since a pressure P and/or a volume V are changed according to a change in a temperature, the tension of the overhead wire can act in a direction in which the change portion of the volume of the gas chamber due to the change in the temperature and an amount at which the overhead wire is expanded and contracted due to the change in the temperature are offset.