Staff Mechanical Engineer, Sealing Systems

Number of employees

300

Menlo Park, CA

Posted on: 2026-09-18

Category: energy

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Employment type:

Full time

Experience required:

Intermediate

Salary

$172,000.00 - $230,000.00

About the company:

Mainspring Energy is a power infrastructure company that designs and manufactures the Linear Generator, a novel primary power solution that delivers firm, flexible, and low-emissions electricity at the point of need. The company serves a wide range of markets including utilities, data centers, enterprise customers, and industrial operations, offering modular units that can be deployed quickly and scaled from hundreds of kilowatts to hundreds of megawatts. The Linear Generator is capable of operating on multiple fuels including natural gas, biogas, and field gas, and is designed to transition seamlessly to zero-carbon fuels over time.

About Mainspring

Mainspring Energy manufactures and delivers fuel-flexible, low-emissions local power solutions that rapidly add new capacity and deliver reliable, affordable, and sustainable electric power. The company began commercial shipments of its Mainspring Linear Generators in 2020 and today has hundreds of megawatts in advanced development and field operations for leading Fortune 500 companies, data centers, and utilities. Mainspring also partners with global energy leaders including AEP, NextEra Energy Resources, Schneider Electric, and more.

The core values that ground our work, guide our decisions, and connect us together:

  • Pragmatic Optimism
  • Excellence without Ego
  • Proactive Collaboration

Does your experience not meet all of our posted requirements? Studies have shown that some people are less likely to apply to positions unless they meet every listed requirement. At Mainspring, we are committed to building a diverse, inclusive, flexible, and collaborative environment, so if you want to help us transition the world to clean and affordable electricity, and don’t meet all posted requirements for a particular role, we’d still love to hear from you. Mainspring can sometimes be flexible enough to shift responsibilities for the right person, or otherwise identify open or upcoming roles that may better fit your professional background.

In more traditional words, Mainspring Energy, Inc is an Equal Opportunity Employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, or protected veteran status and will not be discriminated against on the basis of disability.

This compensation and benefits information is based on Mainspring Energy's estimate as of the date of publication and may be modified in the future. We generally do not negotiate on salary once we have made an offer. The level of pay within the range will depend on a variety of job-related factors that may include location, relevant prior experience and/or education, or particular skills and expertise. New hires joining the company tend to be paid within the starting base pay range noted above, with opportunities to increase pay over time based on development of additional skills, competencies, and company-specific knowledge.

Job Overview

The Rings team owns one of the hardest technical problems in the Linear Generator: a piston and ring system that seals without liquid lubricant. Getting this right is foundational to the product’s low emissions and maintenance business model. The design space is demanding, with complex sealing geometry, demanding thermal and pressure conditions, and material performance and system behavior that all need to be considered simultaneously. Progressing the ring service interval  is one of the most important development programs at Mainspring. As a Staff Mechanical Engineer on this team, you will take ownership of a significant piece of that challenge.

What You’ll Do

  • Lead ring and piston development projects, including setting requirements and scope, developing novel designs, reviewing colleagues' designs and analyses in detail, and building production introduction plans

  • Design complex moving parts in the piston and ring system, from originating ideas through detailed design, build, test, and evaluation of performance

  • Assess and root cause failures that involve coupled thermal, structural, materials, and fluid interactions, balancing analysis with hands-on physical intuition

  • Design and run effective test campaigns, using both benchtop rigs and in-generator experiments, to validate designs and accelerate learning

  • Discover and define requirements on surrounding subsystems to improve ring and piston performance

  • Collaborate closely with a talented engineering team in a fast-paced, iterative environment to find the best solutions

  • What We’re Looking For

  • Master's degree in Mechanical Engineering or equivalent with at least eight years of experience, or a Ph.D. with at least five years of experience

  • A proactive and collaborative work style suited for a dynamic R&D environment where priorities can evolve as you learn, including comfort with problems that cross team boundaries and engineering disciplines

  • Experience designing high-performance, precision parts from R&D through to production release

  • Fluency in SolidWorks or a comparable CAD package.  Comfortable using structural and thermal FEA as a design tool (Ansys is a plus)

  • Ability to generate 2D drawings for manufacturing, including comfort with GD&T

  • Excellent physical understanding and intuition in structural mechanics and heat transfer; strength in tribology, fluid mechanics, or thermodynamics is a plus

  • A systems approach to problem solving: Prefers to look at the whole system to identify negative interactions and opportunities for improvement

  • Nice to Have

  • Excellent understanding of thermodynamics, experience interacting with a complex thermodynamic system.  Power generation, energy storage, and aerospace (especially turbomachinery or propulsion) are all extremely relevant

  • Experience designing for high-cycle fatigue and high-pressure, high-temperature environments.  Experience with super alloys is a plus

  • Fluency in Python programming for data analysis, and experience developing and validating simplified models of systems and subsystems to inform failure analysis and design

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