Disassembly, disassembly and diagnosis of hydraulic components

The hydraulic fault analysis is a process of deepening, from the outside to the inside of the field after the experiment will make further observation on the dismantling and fault of hydraulic parts.

The disassembly and disassembly of hydraulic components should pay attention to the following items: first, release the system pressure, and then observe and disassemble the hydraulic components related to the sealing pressure chamber. Prepare oil collection equipment to collect liquid oil. Disassembly and disassembly of hydraulic components shall be carried out on a clean site, in case the dust is mixed during the assembly and mainly prevents dust from entering the system from the opening of the open pipe. Disassembly, disassembly and assembly of hydraulic components can not force too much, so as not to damage the hydraulic components. Attention should be paid to the assembly relationship of the parts in the hydraulic components to avoid assembly and installation errors. Some matching parts (such as axial piston pump plunger and cylinder bore) is optional, and must ensure that the re assembly with the original matching relationship.

The disassembly, decomposition and observation of various hydraulic components are introduced respectively.

1. dismantling of pump components

(1) disassembly and disassembly of gear pump and observation test: the structure of still gear pump is shown in Figure 5, one and 5. Disassemble the gear pump to check the following aspects of the pump:

The wear and tear of the front and back cover of the pump is related to the leakage and temperature rise in the pump, the wear of the gear end face and the wear between the top of the gear and the pump case. These mills are also related to pressure and flow rates.

The fracture of the pump shaft is related to the non oil supply; the wear of the bearing is related to the fluctuation of pressure and the increase of noise; the damage of the seal is related to the external leakage.

(2) disassembly and disassembly of vane pump and observe the structure of side test type YBI vane pump, as shown in figure 5-6. Open the vane pump, the pump can be checked: wear stator curve, valve plate wear, the wear and output flow, pressure drop, leakage increases, the heating element, is also concerned with the increase of pressure fluctuation. Whether the rotor is in correct installation direction is related to noise increase. The wear of rotor end surface and the wear of rotor blade slot are related to the increase of internal leakage. Whether the rotor is broken is related to the decrease of flow rate and pulsation, as well as to the increase of noise. Whether the blade is stuck in the blade slot is related to the decrease of flow rate and pulsation. The wear of blade is related to noise increase. The wear of bearings is related to the increase of noise. The wear of the seal is related to the external leakage. Whether the shaft is broken, whether the deposition of debris or other dirt in the pump.

(3) axial piston pump Demolition and decomposition and observation, test SCY axial piston pump structure, as shown in figure 5-7. Disassemble the axial piston pump, the pump can check whether the valve plate: wear, trenching, clearance between the plunger and the cylinder hole is too large, the wear and the pressure and flow rate decreased, the leak leakage increased symptoms. Whether the center spring is weak or broken is related to the decrease of pressure and flow rate. When the plunger damping hole is blocked and the friction between the sliding boots is dry, the pump is screaming during operation. Whether the slipper and plunger head is loose is related to noise increase. The wear between slipper and swashplate is related to the decrease of pump efficiency, heating and noise. Whether the internal components due to cavitation damage surface, whether the deposition of debris and dirt in the pump, etc..

2. dismantling of valve components

(1) disassembling and disassembling the overflow valve and observing the side pilot relief valve structure as shown in figure 5-8. Disassemble the relief valve to check the following aspects: whether the main valve core is stuck and the pressure adjustment is invalid. The main valve and valve seat between the seal is normal, whether there is foreign matter, and the system is no pressure related. The main valve core hole is blocked and the damping system without pressure. The wear of the mating surfaces between the upper part of the main valve and the valve cover is not related to the pressure adjustment. The main valve and the valve hole with the surface is a rough, clamping phenomenon and pressure fluctuation, pressure rise lag symptoms, but also related to internal leakage. Whether the main spring is weak or broken is related to the vibration, noise and pressure of the valve. Pilot weeks and valve seat wear, and valve rubbing, noise and pressure adjustment is not high. Whether the pressure regulating spring is weak or not is related to the rubbing and noise of the valve.

(2) the valve removed but decomposition and observation of electromagnetic valve test Liuhe structure as shown in figure 5-9. Disassemble and disassemble electromagnetic (electro hydraulic) reversing valve, which can check the following aspects of the valve: whether the valve core is stuck in the valve hole or not. Whether the clearance between the valve core and the valve hole is too large is related to the leakage in the valve and the hydraulic cylinder going. Whether the reset spring is weak or damaged is not related to the problem of non resetting or resetting. Whether the push rod is bent is not sensitive to the commutation. Whether the seal is damaged is related to the external leakage.

   (3) the demolition of the speed control valve is broken down and the structure of the current M.J test speed control valve is shown in figure 5-10. Disassemble the speed regulating valve to check the following aspects of the valve: whether the pressure valve is stuck, and the failure of pressure compensation. The valve end of the hole is blocked (figure 5-10 a) associated with the failure of pressure compensation. Whether the throttle valve is stuck is related to the invalid adjustment. Whether there is dirt on the throttle valve is related to the instability of the actuator at low speed.

3. dismantling of hydraulic cylinder and hydraulic motor

(1) disassembly and disassembly of hydraulic cylinder and observation test, double acting single piston rod hydraulic cylinder, as shown in figure 5-11. Dismantling the hydraulic cylinder can check the following aspects of the hydraulic cylinder: the gap between the cylinder bore and the piston is too large, and the leakage, thrust and speed decline. Whether the seal on the piston is worn or aged is related to internal leakage, thrust and speed drop. Whether the hole is partly worn is related to the hydraulic cylinder creeping. The sealing of the piston rod seal on the end cap is correct and related to external leakage. Whether the piston rod is bent or not is related to the crawl. The piston rod and the cylinder head seal bad, whether napping leakage increased. The connection between the piston and the piston rod is reliable and related to the reversing impact. Whether the buffer is worn is related to the impact of the pressure.

(2) remove the life of axial piston hydraulic motor test and observation of the decomposition of axial piston hydraulic motor structure as shown in Figure 5-12: disassemble the hydraulic motor, it can check the following: wear between the cylinder and the valve plate and the inner leakage of rotary and slow and weak related. The wear between the plunger and the cylinder bore is related to internal leakage and slow rotation. Whether the tight spring is weak or not is related to internal leakage and slow rotation. Bearing wear is related to abnormal noise. Whether the accumulation of debris in the housing and dirt and so on?.

  (3) the disassembling and observing of the piston type low speed and big torque hydraulic motor, the structure of the radial piston type low speed and big torque hydraulic motor is shown in figure 5-13. Disassemble and disassemble the hydraulic motor. Check the following aspects: the wear of the valve spindle is related to the slow rotation, weakness and internal leakage. The clearance between the plunger and the cylinder bore is too large, which is related to the slow rotation, weakness and internal leakage. Whether the plunger stuck is related to the speed of rotation. The wear of the collecting shaft is related to the slow rotation, weakness and internal leakage. Whether the bearing is damaged is related to abnormal vibration.

Numerical standard for 4. component wear discrimination

A quantitative numerical standard is required to determine the wear of hydraulic components. Table 5-5 lists the error margin of the grinding head of the Shao sub compression element. Other components can also be referenced to the data in the table to determine wear. In addition, the wear limit of the components can be determined according to the hydraulic component manufacturing standards.