Hermetic Actuators

Our PRIME MOVER™ actuator is a unique linear actuator that provides superior reliability and maintenance-free performance.


  • Provides hermetic, zero leakage, clean actuation
  • Operates in harsh environments
  • Operates at extreme temperatures
  • Actuates across a pressure boundary

This type of actuator is popular with semiconductor and vacuum equipment manufacturers due to its superior reliability, contamination-free operation, compact design and maintenance-free operation.


PRIME MOVER™ uses a welded metal bellows (essentially a hermetic spring) as the force generating mechanism instead of a traditional piston. As a pressure differential is applied across the bellows, it compresses or extends. If external pressure is applied, the bellows compresses, extending the actuator. If pressure is removed, the bellows spring force retracts the actuator. Double actuating versions are also available.

Design Fabrication Cost-of-Ownership

The Senior Advantage

  • Experience – Decades of proven service
  • Speed – Custom designs fast and right
  • Flexible – Hydraulic or pneumatic, double actuation, etc.
  • Reliability – Contamination free
  • Extreme temps/pressure & vacuum operation

The Senior Advantage

  • All-welded construction to highest quality standards
  • All metal / withstands exotic/corrosive fluids, etc.
  • Zero friction / Zero leakage
  • Trouble-free operation (accurate and repeatable)

The Senior Advantage

  • We “engineer-in” ultimate reliability & extreme performance
  • Zero maintenance/service
  • Extended lifecycles
  • No contamination / Downtime risks

Product Resources

Prime Mover™ Actuator Design Data Sheet PRIME MOVER Actuators brochure


“Just-right” solution delivers for IC manufacturer

An existing pneumatic actuator was repurposed by a major producer of semiconductor equipment for a new application. The existing actuator performed sub-optimally in the new application due to lower forces, higher operational life requirements, and more aggressive processing chemistries.

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Extended service life from one year to ten

The legacy design for a thermal actuator relied upon an elastomer-encased wax medium. Unfortunately operating temperature extremes rapidly degraded the elastomer, resulting in a very high rate of failure for this device.

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Synchronized Pneumatic Actuation

Our customer was looking to improve the performance of their wafer handling system. Their historical approach involved the use of an air cylinder and a welded metal bellows to seal the penetration into the vacuum chamber.

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