To provide a device for diagnosing failure of a hydraulic cylinder capable of easily diagnosing a failure of plural hydraulic cylinders connected in parallel with each other through a hydraulic circuit.
A pair of hydraulic cylinders 7, 8 are connected in parallel with each other through hydraulic circuits 11, 12, and a direction indicating flow meter 17 for detecting the flowing direction of the hydraulic oil is provided in the hydraulic circuit 11 of the dead load holding side of the hydraulic cylinder 7. With this structure, when an internal leak is generated in the hydraulic cylinder 7, for example, since the operating liquid flows from the hydraulic circuit 11 of the dead load holding side to the hydraulic circuit 12 through the inside of the hydraulic cylinder 7 when a control valve 13 is positioned at a neutral position, flowing direction of the hydraulic oil is detected by a direction indicating flow meter 17 so as to confirm the generation of the internal leak of the hydraulic cylinder 7. Since the hydraulic oil flows out of the hydraulic cylinder 7 to the hydraulic circuit 11 of the head load holding side when the internal leak is generated in the hydraulic cylinder 8, flowing direction of the hydraulic oil is detected by the direction indicating flow meter 17 so as to confirm the generation of the internal leak of the hydraulic cylinder 8.
UNO KEIICHIRO
NAMATAME TETSUO
