The hydraulic pressure relief valve that the Italian manufacturer was not willing to do, was delivered in 15 days and guaranteed for 3 years by AAK

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? Because in the pressure reducing control circuit, after the directional valve works, the flow at the valve outlet becomes zero, but the pressure still maintains the originally set pressure. In this case, the flow through the pressure reducing port is only pilot flow. Due to the small pilot flow, which is generally within 2L / min, the pressure reducing port of the hydraulic pressure relief valve is basically close to the fully closed position and the opening is very small. According to the flow continuity theorem, this part of leakage must also flow from the damping hole of the main valve spool, that is, the flow through the damping hole is composed of pilot flow and leakage. The area of the damping hole and the oil pressure in the spring chamber of the main valve remain unchanged (the oil pressure in the spring chamber is determined by the pre compression shrinkage of the pressure regulating spring that has been adjusted). In order to increase the flow through the damping hole, the oil pressure in the lower chamber of the main valve will inevitably increase. Finally, it is determined that the main valve spool of the hydraulic pressure relief valve is too loose or the accuracy is not enough. The engineer was convinced by our whole demonstration and suggested Tony to take AAK as their main hydraulic valve supplier.

AAK produced 30 hydraulic pressure relief valves in 15 days and guaranteed the quality for 3 years. Half a month later, Tony sent an email saying that everything was normal with the hydraulic pump after using AAK hydraulic pressure relief valve. The customer fed back his appreciation to his boss, who was particularly satisfied with his ability to deal with the crisis decisively and paid more and more attention to him.

AAK has been doing what peers are unwilling to do. If you have any problem about hydraulic pressure relief valve, or about hydraulic pressure control valve, you can also contact us to have a small try.

AAK HYDRAULIC VALVE (125) 2021-12-24