What are the common faults of excavator gas control valve?
W4-60C type excavator pneumatic braking system, a gas control valve between the pump and the air reservoir, its main function is the separation of compressed air oil and water, filtered compressed air in the red dust and impurities, to prevent back to pump compressed air in the air cylinder, to ensure the stability of the gas pressure in the range of 0.490-0.637MPa, the highest pressure no more than 0.784MPa. The following troubles often occur in use:
A pressure regulating valve for pressure diaphragm damage and leakage.
Transfer film 6 for the rubber bear because of its frequently repeated punching pressure, repeated hog, reset action, by the gas, water erosion, so often damage the diaphragm, which is the most vulnerable to the control valve malfunction. After the diaphragm is damaged, the compressed gas from the air pump enters the upper part of the regulating valve through the diaphragm, but does not enter the air storage tank, so that the air pressure of the air storage tank can not rise. At this point, the temperature of the regulating valve is easy to rise, the brake system barometer shows insufficient air pressure, and the pressure regulating valve can hear the sound of leakage.
Two, the control valve shell rupture
The valve housing by the upper, middle and lower three parts, which are connected by screws. Because the shell is made of aluminum, it is easy to break the shell if it is disassembled or loaded improperly when disassembling or combining. Failure in the demolition, installation screws, should be diagonal and repeatedly tightened or loosened, the shell according to the force on the surface of the alloy ring is consistent, to prevent damage due to uneven stress.
Three. Filter damage
The filter is mainly used to filter the dust and impurities in the compressed air to prevent such substances from entering the brake system of the excavator. It consists of 30 filters, vacuum pads 32 and 33 composed of a fixed plug, if used for a long time, without timely maintenance, easy to make the filter wire breakage, cleaning pad damage. Therefore, caution should be maintained in the maintenance, if damage should be repaired or changed.
Four, the pressure regulating valve to adjust the pressure is too high or too low
At normal operation, if the gas pressure in the storage tank reaches 0.637MPa, the lower part of the regulating valve is pressure relief, so that the air pressure in the air storage tank is no longer rising. When the gas cylinder pressure is lower than 0.49MPa, it should not be a relief. This pressure can be adjusted by pressing force adjusting screw 1 change in spring 19 (tight gas rises; loosen the pressure reduction) to achieve, such as the air pressure is still not properly adjusted, you can have two conditions: one is the pressure already exceed the standard but failed to exhaust pressure relief. At this point you should consider whether to run the exhaust piston 12 is blocked, as a result of O ring piston round 34 tight, the lower part of the exhaust piston spring 10 is excellent, and the normal pressure gas to push the piston operation, should be uniform grinding ring or outer ring, replace the spring adjustment. If the pressure regulating valve inside the small spring 18 compression tight, thimble 8 difficult to push, plug 9 axial hole plug, etc., can make the pressure can not be unloaded; two is the pressure has not met the requirements began to exhaust pressure relief. This causes a regulator diaphragm leak, two is due to the small spring inside the regulator too loose (or broken), or the thimble can be promoted under low pressure, the pressure regulating valve shell holes continue to leak, causing the system pressure does not rise up. In this case, the adjusting screw 1 on the valve should be removed first, the small spring should be adjusted or replaced, and then the big spring will be adjusted.
Five, the safety valve adjustment pressure is not normal
The safety valve is to ensure the gas cylinder pressure is less than 0.78MPa. If the pressure exceeds 0.78MPa when the pressure relief valve remains, gas cylinder pressure will continue to rise. This may be the safety valve diaphragm 25 leakage, safety valve spring 16 perfect caused; if the pressure does not meet the requirements on the pressure relief, the reason is the weak weak spring, pre tightening force is not enough, valve 26 and valve seat 27 is not sealed. At this time should be adjusted or replacement of defective parts.
Six. The gas in the storage tank flows backwards after stopping
In order to prevent the gas cylinder back after the shutdown, the control valve is provided with a one-way valve 29, if down to pump gas after the gas cylinder back, this failure is because one-way valve spring 28 elastic is too weak or broken and useless, should adjust or replace the spring.
Excavator working pressure to maintain in the range of 0.490-0.637MPa, the maximum pressure shall not exceed 0.784MPa, when the pressure is abnormal, should adjust the pressure valve and the safety valve. When the mechanical adjustment is made, the order of the safety valve should be adjusted first, and the adjustment method is as follows:
Adjust the screw on the regulating screw to loosen the nut, and then adjust the screw to the end, so that the lower exhaust valve can not be opened.
To observe whether the pressure of the safety valve can be discharged from the vent hole at 0.784MPa. If the air pressure is abnormal, the gasket can be adjusted by increasing and decreasing the adjusting shim 23; when the air pressure is low, the gasket is increased; on the contrary, the gasket is reduced; the pressure 0.036MPa can be adjusted by increasing the 1mm gasket.
Adjust the pressure valve adjustment screw slowly withdraw, until the exhaust valve opens until the exhaust, if the pressure is 0.637MPa at this time, is the best.
The repeatedly rub down the brake pedal or the excavator cylinder gas pressure recovery should be observed at this time (exhaust piston off) is between 0.490-0.539MPa, if the rebound pressure is less than 0.490MPa, while the upper vent and exhaust, you should adjust the small spring pressure.
Adjusting and testing repeatedly until it meets the requirements.
