Summary Comprehensive mindmap to Hydraulic Valves: Types, Functions & Symbols

Limits the pressure to a specified maximum value as Flow Controller by
by diverting pump flow back to the tank. changing the the orifice area
Function
Cracking pressure (the pressure at which the valve
begins to open) can be adjusted by adjusting the as Flow Meter by measuring the
external screw, which varies the spring force. Simple Pressure Relief Valve (PRV) pressure drop across the orifice
[Normally closed valve]

Function

Graphical symbol




Compound Pressure Relief Valve Orifice Nee
Function
[Normally closed valve]




Maintains reduced pressures in specified
Function
locations of hydraulic systems


It closes when the downstream pressure Pressure-Reducing Valve
How it works
reaches the valve settings [Normally opened valve]



Graphical symbol




Permits a pump to build pressure to an adjustable
Pressure Control Valves (PCV)
pressure setting and then allow it to discharge oil to
the tank at essentially zero pressure as long as pilot Function
pressure is maintained on the valve from a remote
source.
Unloading Valve



Graphical symbol




Causes the hydraulic system to operate
Function
in a pressure sequence


Sequence Valve