AAK hydraulic pressure relief valve, CASAPPA in use

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.

https://www.aakindustry.com/info-detai , l/hydraulic-relief-valve-aak125

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