MS Series

Spring-Return Hydraulic Actuator


Compact. Simple. Versatile.
Delivering thrust up to 72,000 lbs and SIL-3 Capable. Our Spring-Return Hydraulic Valve Actuator is designed to suit a wide range of valve automation applications; from commodity to severe-service extremes.

electro hydraulic actuator linear valve automation

Taking Spring-Return Actuation to the Next Level:
Hydraulic Version Now Available


  • Bore Size: 1 1/2″ – 14″
  • Rod Size: 1″ – 7″
  • Configuration: Single-Stage
  • Stroke Range: Up to 24″
  • Pressure Rating: 3000 psi


  • Preloads up to 72,000 lbs
  • SIL-3 Capable
  • GT3 Triple Seal Gland for
    Severe Service Applications
  • Fail-Open or Fail-Close
SIL3 Logo
Download Our MS Brochure
Cylinder cutout showing springs of Hydraulic Spring-Return Valve Actuator - MS Series
  • Custom dimensional sizes and thrusts available
  • Springs are pre-compressed and sealed in a factory-installed canister
  • No extended tie-rods required
  • Standard offering – no custom design required
  • Proven seal technology

Safety comes first, stays first. Backed by Cowan Dynamics’ warranty and service/support guarantee.

Valve Compatibility

Our Series MS Spring-Return Hydraulic Actuator is compatible with any process valve that requires linear motion.

knife gate valve actuator

Knife Gate Valve

gate valve actuator

Gate Valve

Globe Valve

Pinch Valve

Dual Speed Manifold of Hydraulic Spring-Return Valve Actuator - MS Series

Dual Speed Manifold

Dual-Speed Cam-Operated hydraulic manifold reduces speed at end of stroke to help prevent water hammer.

spring return hydraulic actuator performance graph

Get Maximum Efficiency with these reliable high (red), standard (yellow), and low (blue) operating temperature ranges

Control and Monitoring Solutions

GT3 Gland for Harsh Environments

GT3 Gland
Triple-seal gland with dual wipers. Rugged metallic scrapper and urethane double-acting wiper deflect contamination away from the rod seal for long service life.


Low Temp

Cast Iron construction for applications where yellow metals are not allowed

Mounting Kits: ISO, MSS & Customized Patterns Available

Mounting Kit
Cowan valve mounting kits can be designed for any linear valve. Mounting kits available in steel and stainless steel construction.

Anti-Rotation Torque Arm:

Maintains constant alignment between valve stem and cylinder piston-rod. Compatible with rotary type switch boxes and beacons.

Field-Adjustable Travel Stops:
To limit stroke for position-seated or limited-travel applications. Ensures valve reaches positive sealing every time without damage to valve internals.

HPU & Gas/Oil Systems

HPU & Oil/Gas System
HPU and Gas/Oil Systems available. Standard and custom units engineered to customer specifications and applications.

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