Hydraulic Pilot Pressure Relief Valve

On Monday afternoon, I received an email from Tony. Tony is a purchasing manager of CASAPPA in Italian, mainly responsible for the purchasing of hydraulic pump components, and the work has been very smooth. Last month, they received a complaint from the largest customer that the pressure at the outlet of the hydraulic pump sometimes rises by itself, resulting in unstable operation of the equipment. The customer's site engineer couldn't solve it and turned to CASAPPA for after-sales service. Although the warranty period has expired, they still need to help customer solve the problem. Their engineers tested various parameters of the hydraulic pump. After comprehensive analysis, they were still uncertain about the root cause, but they suspected that the hydraulic pressure relief valve in the pump is faulty. The engineer asked Tony to contact the original supplier of the hydraulic pressure relief valve and ask him to send a sample of the hydraulic pressure relief valve for replacement and test. It is a local hydraulic valve manufacturer and they still have samples in stock. After receiving samples and commissioning, the engineer's suspicion was proved to be correct. After replacing the hydraulic pressure relief valve, the hydraulic pump worked normally. Tony asked the original hydraulic valve manufacturer to urgently replenish 30 hydraulic pressure relief valves to solve this complaint. The manufacturer said that the shipment has passed the two-year warranty period. At present, there are only 3 samples in stock. The remaining quantity needs to wait in production schedule for production, and can only be delivered after 3 months. If offering this plan to the big customer, Tony would be scolded by the boss. He thought of AAK, because the hydraulic valve failed last year, which was also solved by AAK. Tony established a business relationship with us last October. Now we are also friends besides business. We often discuss the knowledge related to hydraulic valves. His email on Monday is just to ask for help on this hydraulic pressure relief valve. After knowing these conditions, I asked him to send us samples of those faulty hydraulic pressure relief valves, and provide us the drawings of this hydraulic pressure relief valve, noting those special requirements. After receiving and disassembling the samples from Tony, we found that the main valve spool of the hydraulic pressure relief valve was too loose and had increased leakage, then the pressure at the oil outlet increased. The problem should be caused by high-frequency wear or insufficient accuracy of the original shipped hydraulic pressure relief valve. The engineer of CASAPPA asked us to reply why it was determined that it was the problem of the valve spool?

Richard is a purchaser of ATOS company in Italy. Last September, ATOS received a complaint from a South African customer that the starting pressure of the hydraulic pump was often insufficient recently. The field engineer analyzed that the valve spool spring of the pilot hydraulic relief valve of the hydraulic pump was deformed, resulting in the unstable pressure of the hydraulic system. He tried to replace the pilot hydraulic relief valve to solve the problem. The customer questioned the stability of their equipment because it had been used for less than 1 year. After learning about it, the owner asked Richard to solve the customer complaint as soon as possible and replace this batch of pilot hydraulic relief valves. Richard wondered about the problem with the pilot hydraulic relief valve. This pilot hydraulic relief valve was produced by an American company and was re purchased this time. The original manufacturer replied that this pilot hydraulic relief valve has been produced according to the standard. The strength limit and elastic limit of the piano steel wire used meet the requirements. The problem should be caused by improper use by the user. Of course, he can not tell the owner of such results. The original manufacturer was unwilling to take responsibility. Richard contacted nearly 20 hydraulic valve manufacturers, including AAK hydraulic valve. After several rounds of communication, Richard eliminated half of the hydraulic valve manufacturers, and then asked the shortlisted hydraulic valve manufacturers to send their own ready-made pilot hydraulic relief valves. Their company conducted spring elasticity test. Finally, 5 manufacturers were selected to send samples for the second round according to the drawing size of his pilot hydraulic relief valve and improve the spring elasticity. After communicating with Richard, we learned that the service limit pressure of the hydraulic pump is above 350bar and the service frequency is very high. Although the piano wire spring used by Sun, the original American manufacturer, is advanced, special materials must be used for this special working condition. We started to test the special spring first. Richard has received samples of pilot hydraulic relief valves from other 4 factories, but AAK hasn't sent them yet. Richard pushed us several times and we advised that we are still in testing. Richard may think AAK should not be able to do it. AAK engineers spent 3 weeks, 6 times replacing materials and 9 times proofing, determined the special alloy steel spring as a trial, and sent the pilot hydraulic relief valve 30 days later. We specially asked Richard about the test of the pilot hydraulic relief valves from the other 4 manufacturers. Richard advised that if AAK pilot hydraulic relief valve could not pass the test, he would need a new round of looking for suppliers.

In this year, , an customer, visited 5 hydraulic valve factories before and after, and made samples of hydraulic relief valve with 1m inner hole for 3 times, but none of them reached the accuracy requirements. sent samples and met the standard for the 1st time, finally chose to cooperate with . The inner hole accuracy is not enough, which is mainly caused by the different built in equipment of honing machines equipped by many hydraulic valve manufacturers. Conventional honing machines use diamond reamers., Because the main cutting part of the diamond reamer is at the tool head, the tool head wears quickly. After the head is worn, it is very easy to cause the size of the hole bottom to be small, resulting in the poor cylindricity of the whole hole and affecting the accuracy. This is the key to the 5% accuracy error. Many hydraulic valve manufacturers are not aware of this key point. , a purchaser from a hydraulic valve in , has an inquiry for a special hydraulic relief valve, and the inner hole accuracy must be controlled within 1m. checked with the original hydraulic valve supplier, and got reply that only the hydraulic valve manufacturer equipped with high precision honing machine is able to make the hydraulic relief valve with 1m inner hole accuracy. According to the equipment configuration, has contacted with more than 10 hydraulic valve manufacturers, determined to visit 5 hydraulic valve manufacturers, and asked 3 powerful factories to sample the hydraulic relief valve. After testing and comparing the samples received from these 3 hydraulic valve factories, all failed to meet the standard. asked the manufacturer with the highest accuracy to continue to improve the proofing, and there is still 0.1m gap. The factory gave up and introduced HYDRAULIC VALVE to him, maybe can do the hydraulic relief valve with 0.1m inner hole accuracy. According to his hydraulic relief valve drawing, we advised that we can send 1pc hydraulic relief valve quality sample after 10 days. 5 days after successfully sent the hydraulic relief valve sample, Bowen informed that the accuracy met the standard. He wanted to know why so many hydraulic valve manufacturers could not achieve 1m inner hole hydraulic relief valve, even if the hydraulic valve manufacturers promised to do so and they also have high precision honing machines, but several proofing did not meet the standard. How did hydraulic valve achieve it Honing machine is really helpful for the machining of high precision inner hole. Due to different equipment configuration, not every hydraulic valve manufacturer can produce the hydraulic relief valve with 1m inner hole accuracy.

James is the purchasing director of one of our American Hydraulic customers. They are the top 3 in the construction machinery industry in the United States, and their market share is increasing year by year. James is also doing well. In May last year, the MP550-HDD-18 cement delivery pump supplied by their company to a local construction company often failed to reach the rated value for the system pressure during use, and the oil pressure of the hydraulic system can only reach 12MPa. After disassembling the hydraulic system, the engineer found that the joint surface between the conical pilot valve body and the valve seat of the hydraulic relief valve was grinded out with a circle of uneven groove line with a depth of about 1mm for unknown reason. The hydraulic oil flowed back to the oil tank from this groove, and the hydraulic relief valve had no sealing function. The customer wanted Jamesâ??s company to replace the hydraulic relief valve of the same model within 2-3 weeks. If they miss the time, the project progress will be affected. When James purchased this hydraulic relief valve from the original German hydraulic valve supplier again, he was told that they produce this hydraulic relief valve no longer. If he wanted to re-produce it, it would take 35 days and modify the production process and auxiliary equipment, which would require an additional cost of more than 30,000 US dollars. This style of hydraulic relief valve was just purchased by James 2 years ago. When he reported this situation to the president, the president didn't understand why he didn't have an alternative hydraulic valve manufacturer. James realized that the president was unhappy. When he sent the anatomical drawing of this hydraulic relief valve to more than 20 hydraulic valve manufacturers, almost all said that they have no hydraulic relief valve with such structure, James was a little flustered. In March this year, James just purchased a batch of high-precision hydraulic relief valves from AAK. He wanted to see if AAK had a way to solve this thorny problem. When he sent us the pictures of this hydraulic relief valve made in Germany, we asked him to send us the whole complete technical drawings, as well as the use environment and working conditions. The pressure of this hydraulic relief valve is 31.5Mpa and the flow is 200L / min, which is basically consistent with the parameters of the hydraulic relief valve we supplied to them before. However, there is a fatal problem that the internal structure, appearance, shape and size are inconsistent with those of the hydraulic relief valve they purchased in Germany, so it is difficult to install on the transmission line. After learning that the only way is to meet the requirements of the transmission line at the construction site in the United States, AAK engineers designed a new hydraulic system with two pipe joints and an oil plug according