TERM-SERVO-VALVE
Servo Valve
Hydraulic Systems
Also: electrohydraulic servo valve · EHSV · proportional valve
Abbrev: EHSV · SV
Canonical Definition
A high-precision hydraulic control valve that modulates hydraulic flow proportionally to an electrical input signal. Servo valves operate with internal clearances of 1–5 µm between spool and bore. Particle contamination above 3–5 µm in hydraulic fluid causes stiction, scoring of spool surfaces, and flow control degradation. ISO 16/14/11 or tighter cleanliness codes are required to protect servo valve performance and lifespan. Servo valves are used in precision motion control applications including aircraft hydraulics, CNC machine tools, and high-performance industrial systems.
Engineering Context
Servo valves are the most contamination-sensitive components in any hydraulic circuit. A single particle larger than the spool-bore clearance can cause jamming. Hydraulic systems incorporating servo valves require offline kidney-loop filtration to maintain cleanliness codes continuously, not only during operation but during shutdown periods when thermal convection can redistribute settled particles.
Applicable Standards
Related Technologies
Protection Systems
Knowledge Center Articles
KC-00 Governance Metadata
| Permanent ID | TERM-SERVO-VALVE |
| Category | Hydraulic Systems |
| Status | Published |
| Version | 1.0 |
| Last Reviewed | 2026-07-05 |