Manifold block

Method of fault diagnosis of Manifold Block hydraulic system


The fault diagnosis method of hydraulic system includes precision diagnosis method with special instrument and simple diagnosis method. Simple diagnosis is also called sensory diagnosis. It is the maintenance personnel using simple diagnostic instruments and human feeling, combined with personal practical experience of the hydraulic system fault diagnosis method. This method is simple and easy to use and is still widely used. Now I will introduce sensory diagnosis.


(1) Visual diagnosis is to observe the working condition of the hydraulic system with the eyes.

Observe whether the moving parts such as the piston rod of the hydraulic cylinder or the working table work, the speed is fast or slow, and whether the jumping crawl; Observe the process, magnitude and fluctuation of pressure value at each oil pressure point; Observe the temperature of the oil, whether the oil is clean, whether the color change, the amount of oil indicated by the oil standard, the consistency of the oil viscosity, whether there is foam on the surface of the oil; Observe whether there is leakage, dripping and oil scale at the joints of the hydraulic pipeline, the joint of the valve plate, the end cover of the hydraulic cylinder and the transmission shaft of the hydraulic pump; Observe the products processed from the equipment, indirectly judge the working state of the motion mechanism, system pressure and flow stability; Observe the indicator light and indicator block of the electromagnet to judge the working state and position of the electromagnet. To judge the connection between the oil ports of the hydraulic components, the oil filling method, blowing or blowing method can be used. The oil outlet of oil and flue gas is interlinked, and the oil outlet of oil and flue gas is not through.


(2) Auditory diagnostic method is to judge whether the hydraulic system or hydraulic components work normally by ear.

Hear the noise. Listen to whether the hydraulic pump or hydraulic system noise is too large, whether the frequency is normal, whether the relief valve and other components have noise; Listen to whether there is a fine and continuous sound inside the oil circuit board. Two cans of liquid flow. Listen to the hydraulic components and pipe whether there is liquid flow sound or other sound; The “boom” sound is heard in the pipe, which is the flow sound of the pressure oil in the pipe with high pressure and fast flow rate; There is a “buzzing” sound in the pipe, which is the resonance sound when there is no oil in the pipe and the hydraulic pump is running; The sound of “splashing” is heard in the pipe, which is the flow sound of general pressure oil in the pipe; If you listen to the inspection while knocking the oil pipe, you hear the clear sound, there is no oil in the oil pipe, and you hear the muffled sound, there is oil in the pipe. Three percussions. Listen to whether the impact sound is too large when the workbench reversing, whether the hydraulic cylinder piston has the sound of hitting the bottom of the cylinder; Listen to the working state of the electromagnetic directional valve, the ac electromagnet emits a “buzzing” sound is normal, if the impact sound, it is due to the spool action too fast or the electromagnet iron core contact is bad or the pressure difference is too big and the sound.


To judge the flow of hydraulic oil in the oil pipe, a screwdriver can be used, one end is attached to the ear, and the other end is in contact with the part to be inspected.


(3) Tactile diagnosis is to use hand touch parts to sense the movement and temperature rise of parts.

Touch the temperature rise. The temperature of the hydraulic pump shell, the outer wall of the oil tank and the valve body shell, the electromagnet coil, if the finger feels cool, about 20℃ below; If the finger feels warm but not hot, about 30 ~ 40℃; If the finger feels hot and hot but can tolerate, about 40℃ ~ 50℃; If the finger feels hot and can only endure 2 ~ 3s, about 50 ~ 60℃; If the finger feel hot and acute retraction, about 70℃ above. The general temperature above 60℃ is not normal, you should check the cause. Second touch vibration. Touch the moving parts and tubing by hand, you can feel whether the vibration is strong or weak. By touching the oil pipe, you can judge whether there is oil flow in the pipe. If the finger does not have any vibration, it is an empty oil pipe without oil; If the finger has uninterrupted continuous micro vibration sense, it is the oil pipe with pressure oil; If the finger has no regular flutter, it is the oil pipe with a small amount of pressure fluctuation. Three steps to climb. Touch the table with your hand, you can judge the low speed when there is no crawling. Four touch tight. The degree of tightness can be felt by hand swinging the baffle, travel switch, nut, joint, etc.


(4) Olfactory diagnostic method is to smell all kinds of odors with the nose.

The local “coking” smell of hydraulic oil indicates that there is local heating of hydraulic components, so that the surrounding hydraulic oil is burnt, and the heating part can be judged accordingly. Smell whether there is a bad smell or pungent smell of hydraulic oil, if there is, it means that the hydraulic oil has been seriously polluted, can not continue to use; Smell the electrical part of the component whether there is a special electric coke smell, can determine whether the electrical component burned out.


The most critical and difficult part of sensory judgment is the subtle distinction between sound and vibration when they are normal and when they are not, which is difficult to describe in words. This requires the diagnoster to often listen to, touch the sound and vibration of various devices in different states, so as to sharpen the sense and accumulate memory materials of sound and vibration.

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Troubleshooting steps of Manifold Block hydraulic system