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"Saving the World - One Customer at a Time..." ™


Educational Series - Volume 4 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - May 20, 2026


Hydraulic Myth #2


The System Relief Valve

Determines Operating Pressure

TRUTH:

The System Relief Valve sets the maximum allowable system pressure, keeping the system from exceeding safe limits.



The resistance to flow is what actually determines the system pressure, and it varies depending on what your system is doing at that moment.


Note: The Relief Valve must be capable of unloading

the full flow from the pump.

Simple Cylinder Application

Cylinder Extending


System pressure will equal the resistance to the work being done, and in this case 2,300 PSI to move the load.


2,300 PSI is lower than the setting of the Pressure Relief Valve.



Blue = Low PSI


Red = High PSI

Cylinder Reaches End of Stroke


Pressure in the system above reaches a maximum level because the cylinder reaches the end of its stroke.


The hydraulic fluid has no where to go, so the pressure increases to the level set on the System Relief Valve, at which point it unloads all flow to tank.


System Pressure is unable to exceed a pressure greater that what you set at the Relief Valve.

Fundamentals of Hydraulics Classes

Our week-long sessions include two major components of training:


Academic Training (above)

Hands-On Training (right)


(click on images for more information)

Our "Hands-On" training

helps students understand fluid power functionality with actual system components.

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