In the excavator brake air circuit system, a gas control valve is installed between the air pump and the air reservoir. Its main function is to separate oil and water from compressed air. Filter the dust and impurities in the compressed air. Prevent the compressed air in the air reservoir from flowing back to the air pump. During the use of the excavator, the gas in the air reservoir may backflow after shutdown. In order to prevent the gas in the gas reservoir from backflow after shutdown, a one-way valve is set in the control valve. If the gas in the air reservoir flows back to the air pump after shutdown, this fault is mostly caused by the weak elasticity or broken check valve spring. The spring shall be adjusted or replaced.
The working air pressure of the excavator shall be kept within 0.490-0.637MPa, and the maximum pressure shall not exceed 0.784MPa. In case of abnormal pressure, the pressure regulating valve and safety valve shall be adjusted. When making mechanical adjustment, the safety valve shall be adjusted first. The adjustment method is as follows.
1. Loosen the fixing nut on the adjusting screw of the pressure regulating valve. Then screw the adjusting screw to the end so that the lower exhaust valve cannot be opened.
2. Observe whether the safety valve can exhaust from the vent when the pressure is 0.784MPa. If the air pressure is abnormal, it can be adjusted by increasing or decreasing the adjusting shim. When the air pressure is low, add shims, otherwise, reduce shims. The air pressure can be adjusted by 0.036MPa for every 1mm gasket.
3. Slowly withdraw the adjusting screw of the pressure regulating valve until the exhaust valve is opened for exhaust. It is best if the air pressure is just 0.637MPa.
4. Rub the brake pedal of the excavator for several times or deflate the air reservoir. At this time, observe whether the rising air pressure is between 0.490-0.539MPa when the exhaust piston is closed. If the rebound pressure is less than 0.490MPa, and the upper vent vents at the same time. At this time, adjust the pressure of the small spring.
5. Adjust and test repeatedly until it meets the requirements.
