BOOK 2, CHAPTER 21: Servovalve circuits | Power & Motion
Valve Symbols in Process and Instrumentation Diagrams | Tameson.com
Servo and proportional valve symbols
Animation | How schematic symbols for control valves is derived | How 3 position 4 port valve works. - YouTube
Hydraulic symbology 302 – high response valves
Directional Valve Symbols
servo-valves
BOOK 2, CHAPTER 14: Proportional control valves | Power & Motion
Modelling and experimental studies on a proportional valve using an innovative dynamic flow-rate measurement in fluid power systems - Alessandro Ferrari, Pietro Pizzo, Massimo Rundo, 2018
ISO 14617-8 - X2175, Directional servo-control valve with positive overlapping in mid-position, operated by double-acting solenoid, spring return to mid-position
BOOK 2, CHAPTER 14: Proportional control valves | Power & Motion