(1) The hydraulic oil in the transmission is increasing, and the hydraulic oil in the hydraulic tank is continuously reduced. This situation is generally caused by damage to the skeleton oil seal of the working gear pump or the steering pump, causing hydraulic oil to enter the transmission. If there is still this fault after changing the oil seal, the sealed copper sleeve of the working gear pump should be checked; because the copper sleeve is damaged, the high pressure oil will break the skeleton oil seal. The matching clearance between the driving gear shaft of the working gear pump and the copper sleeve is controlled between 0.025 and 0.045 mm, and geometric deviation is not allowed.

(2) The amount of hydraulic oil in the transmission is decreasing, and the amount of hydraulic oil in the hydraulic tank is increasing. This situation is generally caused by damage to the skeleton oil seal (PG45 & times; 62 & times; 12) in the variable speed gear pump, and the hydraulic oil is sucked by the working gear pump.

Another aspect of the working fluid contamination of the piston rod is the contamination of the external environment by the medium. Try to use high-viscosity working oil to reduce leakage; realize the greening of working medium of engineering machinery transmission device as soon as possible, adopt non-sugar hydraulic oil; develop recycling technology of hydraulic oil; develop working medium green additive.