Engineering mechanical hydraulic system fault diagnosis method of some commonly used in the construction of the project mechanical hydraulic system failure diagnosis, often be the site conditions the limit, and in failure as soon as possible after requirements excluded, so as not to affect the construction progress. This paper introduces several common scene of engineering machinery hydraulic system fault diagnosis methods, for reference.

1. The visual inspection

For some of the more simple fault, can pass soon, the fingerprint, ears to hear and smell of the parts were means of inspection.

For example, through the visual inspection can find the rupture, oil leakage, such as loose and deformation and failure imagination, thus, can in time to repair or replacement parts; Use hand holding tubing (especially hose), when there is pressure will have commercial outdated vibration to feel, and no oil through or pressure is too low, it is not the phenomenon. In addition, the hand can also be used to judge the mechanical transmission parts with hydraulic components to whether it lubricates very well, with the hand to feel the way components to shell temperature change, if components shell overheating, show bad lubrication; Ear listens to judge mechanical parts can be the result of a damaged fault point and damage degree, such as hydraulic pump suction empty, overflow valve opens, components, such as issuing fault can make water impact sound or "water ChuiSheng" abnormal sound; Some components will be due to overheating, bad lubrication and corrosion, so the reason and emits an odor, through the smell can judge the fault point.

2. The diagnosis method exchange

The service field in lack of diagnosis instrument or be checked more precision components should not be apart when, should use this law. First will doubt failure to components to be removed, change into new thing or other machines normal, the components of the experiment, see failure can rule out the diagnosis can be. As a E200B carter type hydraulic system working device excavator working pressure, according to experience the relief valve is suspected broke down, and then I put the same model on the site of the relief valve and the excavator swapped the relief valve, ma chine normal work, confirmed that doubt correct. Check the fault diagnosis method with exchange, despite being under the structure, the components reserves, or remove the inconvenience of the factors such as limit, operate up may also more troublesome, but for such as balance valve and relief valve, check valve, small volume, easy to assemble components, use this law or more convenient. Diagnosis method can avoid exchange due to blind to remove the hydraulic element has decreased. On the above fault if not exchange method inspection, and direct the Lord removed suspicious relief valve and the dissembling, if the elements have no problem, refitted might affect their performance after.

The hydraulic system's fault, but according to the working principle of the hydraulic system, according to the power components-the control elements-execution element in the order on the drawing system forward reasoning analyse the reason of failures. If a mining mobile arm to work, from the analysis on the principle that work is due to general decline or flow caused by hydraulic decrease. From the picture it looks system, cause pressure drops or flow decrease the possible factors are:

One is the fuel tank, such as lack of oil absorption, oil tube jam and the vent air not clear;

2 it is hydraulic pump leakage, such as hydraulic pump piston pair of fitting clearance increases;

Three is the manoeuvring valve on the relief valve pressure to adjust too low or leakage is serious;

Four is moving arm hydraulic cylinder overload the adjustment for low pressure or leakage is serious;

Five is not free to oil etc. Consider these factors, then according to the existing examination results, ruled out some factors, narrowing the scope of the fault, until the fault point and to find out.

The hydraulic system failure diagnosis, according to the system working principle, to master some rules or common sense; One is the failure analysis process is gradual change or mutations, if be gradual, general is due to the original size and cooperate with wear the change of the original function loss; If a mutation, is often caused by sudden damaged parts, if spring break, seal damage, sports a card to die or contamination jams, etc. 2 it is to distinguish is wearing parts or not wearing parts, and a high frequency motion a heavy, or for easy to the failure of the hydraulic components, such as hydraulic pump piston vice, assignment vice, variable servo and offer the hydraulic cylinder, etc. And be in low frequency and light load or basic relatively stationary components, failure is not easy, such as reversing valves, order valve, not easy and rotary piston failure. Master these rules, the rapid judge fault parts which play a positive role.