Core tips: what are the common faults of excavator gas control valves? In the brake gas system of W4-60C excavator, the gas control valve is installed between the air pump and the gas reservoir. The main function is to separate the oil and water in the compressed air, filter the red dust and impurities in the compressed air, prevent the compressed air from the air pump to flow back to the air pump, and ensure the pressure of the gas to be steady in the range of 0.490-0.637MPa and the most high pressure No more than 0.784MPa
In the brake gas system of W4-60C excavator, the gas control valve is installed between the air pump and the gas reservoir. The main function is to separate the oil and water in the compressed air, filter the red dust and impurities in the compressed air, prevent the compressed air from the air pump to flow back to the air pump, and ensure the pressure of the gas to be steady in the range of 0.490-0.637MPa and the most high pressure The force is not more than 0.784MPa. The following faults often occur in use:
Leakage of pressure valve due to damage of the diaphragm
The pressure regulating film 6 is a rubber product. Because of its frequent pressing of air pressure, repeated arch and reset action, corrosion of gas and water, it often causes the diaphragm to be damaged, which is the most likely failure of the control valve. After the diaphragm is damaged, the compressed gas coming from the air pump enters the upper part of the pressure regulating valve through the diaphragm, and does not enter the storage tank, causing the pressure of the gas cylinder to rise. At this time, the temperature of the regulating valve is easy to rise. The barometer of the brake system shows that the air pressure is insufficient, and the air leakage sound can be heard at the pressure regulating valve.
Control valve shell rupture
The valve shell is composed of three parts: upper, middle and lower parts, which are respectively connected by screws. As the shell is made of aluminum material, when disassembly or combination, improper removal and installation of screws will easily break the shell. When the fault is dismantled or installed, the screw should be tightened or loosened on several times, so that the shell is consistent with the force on the face to prevent damage due to unequal force.
Filter damage
The filter is mainly used to remove dust and impurities in compressed air and prevent such substances from entering the brake system of the excavator. The utility model is composed of a filter net 30, a dust suction pad 32 and a fixed screw plug 33. If the service is not used for a long time, it is easy to damage the filter copper wire and the dust cushion. Therefore, it should be carefully maintained during maintenance. If damaged, it should be repaired or changed in time.
The adjustment pressure of the pressure regulating valve is too high or too low
When working normally, if the gas pressure in the cylinder reaches 0.637MPa, the lower part of the pressure regulating valve will release pressure, so that the air pressure in the storage tank will no longer rise. When the air pressure in the cylinder is less than 0.49MPa, it should not be released again. The adjustment of the air pressure can be achieved by adjusting the screw 1 of the large spring 19 (tightening, rising of gas, loosening, and lowering the pressure). If the pressure is still not normal after the adjustment, there are two kinds of conditions: one is that the pressure has exceeded the standard but can not exhaust the pressure and pressure. At this time, the exhaust piston should be considered to be blocked when the piston is 12. For example, because the O ring 34 of the piston circle is too tight, the lower spring 10 of the exhaust piston is excellent, and when the normal pressure gas is unable to push the piston to run, the outer ring of the seal ring should be evenly grind or the spring is changed. If the pressure valve internal small spring 18 compression is too tight, the thimble 8 is hard to push, the plug is blocked by 9 axial holes and so on, the pressure can not be unloaded; two is the pressure when the pressure has not reached the requirement. This reason is the leakage of the pressure regulating film, two is that the small spring in the pressure regulating valve is loose (or even broken), or the thimble can be pushed under the lower pressure, so that the small holes on the pressure regulating valve shell are constantly leaking, causing the system pressure to rise. In this case, the adjusting screw 1 on the valve should be unloaded first, the small spring should be adjusted or replaced, then the large spring should be adjusted.
The adjustment pressure of the safety valve is abnormal
The function of the safety valve is to ensure that the air pressure in the cylinder is not more than 0.78MPa. If the pressure exceeds 0.78MPa, the relief valve will not release pressure, which will increase the pressure in the cylinder. This may be caused by the 25 leakage of the safety valve diaphragm and the spring 16 of the safety valve; the pressure is unloaded if the pressure is not reached. The reason is that the spring is weak, the pretightening force is not enough, and the valve 26 is not sealed with the seat 27. The damaged parts should be adjusted or replaced at this time.
Reflow of gas in the reservoir after shutdown
In order to prevent the backflow of gas in the storage cylinder after shutdown, there is a one-way valve 29 in the control valve. If the gas in the storage cylinder is back flow back to the air pump after the shutdown, the fault is mostly because the spring 28 of the valve spring is too weak or broken and should be adjusted or replaced.
The working pressure of the excavator is kept in the range of 0.490-0.637MPa, and the maximum pressure should not exceed 0.784MPa. When the pressure is abnormal, the pressure regulating valve and the safety valve should be adjusted. In order to make mechanical adjustment, the sequence of safety valve should be adjusted first.
1. Unscrew the retaining nut on the adjusting screw, then screw the adjusting screw to the end, so that the lower exhaust valve can not be opened.
Observe whether the pressure of the relief valve can vent from the exhaust port at 0.784MPa. If the pressure is abnormal, the cushion can be adjusted by adding or reducing the gasket 23; when the pressure is low, the gasket is added, and the gasket is reduced, and the pressure 0.036MPa can be adjusted for every 1mm gasket.
3. Adjust the adjusting valve of the regulating valve and withdraw slowly until the exhaust valve is opened for exhausting. If the pressure is just 0.637MPa, then it is the best.
4. Repeatedly rubbing the brake pedal of the excavator or letting the gas reservoir deflate. At this time, it is necessary to observe whether the rebound pressure (the exhaust piston closes) is between 0.490-0.539MPa, if the recovery pressure is less than 0.490MPa, and the upper exhaust hole is at the same time exhaust, and the pressure of the small spring should be adjusted at this time.
(5) adjusting and testing repeatedly until the requirements are met.
