| 摘要 |
PROBLEM TO BE SOLVED: To provide a dirt-state diagnostic device for a hydraulic fluid, which continuously detects a solid body mixed in the hydraulic fluid for a hydraulic circuit used for construction machinery such as a hydraulic backhoe and is compact and costless. SOLUTION: The dirt-state diagnostic device is composed of a motor 2, a rotating shaft 3 driven by the motor 2, a bush 5, an electric circuit controlling the motor 2 and having a current detector 31 detecting a current flowing through the motor 2 and a controller 32, to which a current signal from the current detector 31 is input and which decides the dirt state of the hydraulic fluid on the basis of the input signal. The rotating shaft is turned, making the hydraulic fluid flow into a clearance section 11 between the rotating shaft 3 and the bush 5, and torque fluctuation loaded to the rotating shaft 3 is detected by the current flowing through the motor.
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