Unloading Valves (Full Lecture)

In this lesson we'll examine another member of the pressure control valve family known as the unloading valve. Unloading valves are commonly used to divert pump flow at low pressure. Additionally, we'll examine a differential unloading relief valve used exclusively for accumulator circuits and unloading schemes making use of pressure switches and solenoid operated valves. (Full Lecture)

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[helicopterpeace]

Hello Jim, thank you for your video lectures. They have very valuable. Anastasia

[augustyn]

Very good video. helped me touch up on a few issues. I was looking for a cost affective way to use a gas operated positive displacement pump with closed center valves.

[michaelcostello]

Unloading valve is also called accumulator charging valve. I searched this first on your channel but could not find this video. Perhaps give it both names so one can find it. Thanks for great video. mike

[johnevan]

Hi Jim, again thanks for these lecture.These Differential Unloading Relief Valve is the same as Unloading Relief Valve?Also the difference in pressure is constant bet the pump side and accumulator side?Some hyd manufaturer dont carry these item.Ive encounter an Unloading Relief Valve w/ the check valve incorporated wit in.Really learns a lot from your lectures.More power!!

[commenter]

Hey!!! There’s damn good restaurant at Petro truck stop. Called Iron Skillet! 😁

[arslanahmad]

I read in a pump data sheet that starting pressure should not be more than 20 bar for that pump. Is this restraint induced by the pump mechanical design or the prime mover motor's electrical characteristics?

Will this restraint prohibit the use of the third unloading method?

[danalex]

In both scenarios, the pilot operated UV and the differential area UV there are pressure cycles that the accumulator goes through .
The only difference i can see that is in the differential area UV you can control the pressure range and if possible minimize it but in the pilot operated UV you do not have that level of control . Is there any other advantage ?

[heavyjay]

Wouldn't it be more efficient to just have pump A turn off at 500 psi?

[commenter]

Turning pump on and off - will kill the motor very quickly. And will be even more annoying than listening to system load and unload.

Just get a darn Pressure Compensated pump, and get rid of the whole shebang all together.