Excavator control valve spool repair

Repair of excavator control rake Dragged Liuyang users of Luoyang Engineering Machinery Factory purchased my Taiwanese stomach type 32 hydraulic excavator. During the construction process, the arm cylinder was weak and accompanied by natural drooping phenomenon. At first, it was suspected to be hydraulic pressure. Cylinder leak, after replacing the piston combination seal, the phenomenon still exists. After the stress test, we think it may be due to the leakage of the spool of the combined valve group. In order to verify the above judgments, the valve group was removed and cleaned, and each control valve port was placed facing up. Then, kerosene was injected at each control port. After about 20,1, it was found that the liquid level at the port was significantly decreased. . The valve group is reset by a spring and the control ports should be in the closed state when in the neutral position, which can confirm that the valve group has internal leakage. Remove the screw from the user's disassembled part to remove the spool end cap, remove the parts in order and pay attention to protect the sealing ring on the valve core from damage, and clean the serial number.

The micrometer was used to measure the actual size of the outer diameter of the valve core, 027.86, and the actual size of the valve hole was measured using the inner diameter of 1000 mm. The naked eye had a local picking phenomenon.

Grinding repair According to the measured size of the valve hole, the root grinding rod is finished with cast iron. The dimensions are ¢28.03mm and 8.0028.04, and the groove width and groove depth are both l5mm in the forward and reverse direction of the rod. The diameter of the root rod ¢ 28.05 +0.02, +0.04, the light rod for the final test. The kerosene is immersed in the valve hole to be ground for about 1 h. Then, the abrasive groove of the 28.03 mm process grinding rod is coated with alumina abrasive, inserted into the valve hole to reciprocate and rotate, and stops after about 1.5. Grinding rod, cleaning and testing the size of the rod and hole; with a diameter of 28.04mm grinding rod grinding again according to the above method about lh. After cleaning the valve hole, the size of the test valve hole does not appear to increase the size of the phenomenon of the last 28.05 1 less The test rod is supplemented by kerosene lubrication and is plunged into the hole of the insert valve. If the hand feels suction and the phenomenon of blockage occurs, the fit surface of the valve core with the outer diameter of the valve core must be 27.86 mm, and the fit surface of the valve hole is ground on the cylindrical grinder. Prepare the electroplating solution according to the fixed ratio, use the brush plating method on the valve core, as a benchmark, finely grind the valve core, make the final size control in 28.06 test leak installation, clean the parts and assemble them in order, use the above The method of injecting kerosene was leak tested. After about two years, no significant drop was observed in the fluid level at the port. After the valve group was reloaded, the pressure indicators returned to normal and the failure disappeared.

Repair process should pay attention to the following matters when grinding the valve hole, should pay attention to even when not in touch with the stick body temperature and observing the color change of the grinding stick surface to prevent the valve hole diameter increase or out of round; should be based on the material of the valve core And the thickness of the plating, the preparation of a suitable plating solution to ensure the quality of the plating layer; in the brush plating process should make the valve core surface clean and purify, and enable it to rotate at a uniform speed, so that the coating is uniform, strong adhesion.

The original diesel engine smoke emission limits are unreasonable, and the effect of the free-accelerating smoke degree is overestimated and the use of a filter paper smoke meter to measure the free acceleration smoke is inaccurate. The standard was changed by the 838471999 standard. Therefore, the emission of diesel engines for construction machinery should not be formulated with a conflicting emission standard, such as the discharge limit of the exhaust gas of small and medium-duty diesel engines in the category of 89999.

Since China cannot currently manufacture opaque smoke meters, the new standard is still difficult to implement. In addition, the standard itself is not perfect. After being verified by domestic manufacturers, the use of full-flow opacimeters to measure the free acceleration smoke has great errors, and it does not apply to the 0838471999 standard. It is suggested that the implementation period of the new standard be postponed, so that China's construction machinery diesel engine will strive to quickly increase its ability to compete fairly with developed country companies in a limited transitional period.

In addition, it should actively participate in the work of the 18,170 International Standardization Organization, promote the international standards for smoke emission tests, and standardize the smoke measurement instruments and smoke units, so that the Chinese diesel smoke emission standards will gradually adapt to the international discharge regulations. the trend of.

Received date 20003 adjacent 5 construction machinery, 20006

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