To provide a fault diagnostic device for a hydraulic cylinder capable of easily carrying out a fault diagnosis for a plurality of hydraulic cylinders connected in parallel through a hydraulic circuit.
A pair of hydraulic cylinders 7 and 8 are connected in parallel thorough hydraulic circuits 11 and 12, hydraulic fluid filters 17 and 18, and differential pressure gages 19 and 20 for detecting the differential pressure between the inlet and the outlet of each hydraulic fluid filters 17 and 18 are provided in the hydraulic circuit 11, hydraulic fluid filters 23 and 24, and differential pressure gages 25 and 26 are provided in the other hydraulic circuit 12 as well, and a buzzer 29 operated when the differential pressure is detected in these differential pressure gages. Thereby, when a fragment of a seal member is captured in the hydraulic fluid filter 17 and excessive differential pressure is detected in the differential pressure gage 19, for example, internal leak caused in any of the hydraulic cylinder 7 or 8 is reported to an operator in a cab 2a.
UNO KEIICHIRO
NAMATAME TETSUO
