Senior Staff Mechanical Engineer

Job Description

Job Description

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

Mainspring is seeking a Senior Staff Mechanical Engineer to shape technical direction across multiple teams, systems, or major program areas within our Linear Generator platform. In this role, you will guide system-level design decisions, resolve complex cross-functional tradeoffs, identify risks that may not be visible within individual projects, and create technical leverage through architecture, standards, validation strategy, and high-quality decision-making.

This role is intended for engineers who have already demonstrated advanced technical ownership within a major subsystem, team, or technical area and are now ready to influence outcomes across a broader part of the organization. A strong candidate should be able to operate with high autonomy, frame ambiguous system-level problems, align stakeholders, improve technical decision quality across projects, and help teams avoid rework caused by weak assumptions, incomplete validation, or missed integration risks.

Candidates who primarily provide technical leadership within one team, subsystem, or technical area may be better aligned to a Staff Mechanical Engineer role, while candidates who serve as a company-level technical authority in a critical domain may be better aligned to a Principal Mechanical Engineer role.

• Lead technical direction for a broad system, platform area, discipline, or group of related mechanical projects with high ambiguity, system-level tradeoffs, and major program impact.
• Guide architecture, system, subsystem, or platform-level design decisions that affect multiple projects or teams, balancing technical performance, reliability, cost, manufacturability, serviceability, scalability, and business priorities.
• Frame complex cross-functional problems at the right level, identify critical tradeoffs, and drive alignment on practical technical paths forward.
• Establish analysis, validation, test, and data strategies for major technical decisions where the available evidence may be incomplete, imperfect, or spread across models, experiments, field data, and production learning.
• Identify system-level risks, recurring failure modes, integration gaps, and organizational blind spots that may not be visible within individual projects.
• Create technical leverage across teams through design reviews, risk reviews, architecture discussions, technical strategy, standards, methods, troubleshooting, and guidance on high-consequence decisions.

• BS, MS, or PhD in Mechanical Engineering or a similar engineering field, with demonstrated success providing technical leadership across complex mechanical systems, subsystems, or major program areas.
• Repeated experience developing, validating, releasing, and improving complex hardware across multiple design cycles, project types, failure modes, and implementation environments.
• Strong system-level mechanical judgment, including the ability to balance performance, reliability, cost, manufacturability, serviceability, scalability, safety, schedule, integration, and business priorities.
• Demonstrated ability to resolve ambiguous, cross-functional technical problems where ownership, requirements, evidence, or tradeoffs are not initially clear.
• Proven ability to use analysis, testing, data, field learning, production learning, and engineering judgment to make or guide high-consequence technical decisions.
• Strong communication and influence skills, including the ability to align stakeholders across teams and levels of the organization around technical strategy, risks, tradeoffs, and recommended paths forward.

• Experience serving as the technical lead or subject matter expert for a broad system, product area, platform, or discipline.
• Experience developing hardware for energy systems, engines, generators, compressors, pumps, thermal systems, fluid systems, structures, high-cycle fatigue environments, precision alignment systems, electromechanical systems, or industrial equipment.
• Experience creating design standards, architecture principles, validation methods, risk frameworks, review practices, troubleshooting methods, or other reusable approaches that improve engineering execution across teams.
• Experience with reliability strategy, accelerated life testing, failure analysis, structured root cause analysis, design of experiments, risk-based validation planning, or system-level trade studies.
• Experience influencing major technical decisions across engineering, manufacturing, quality, supply chain, suppliers, service, product, or leadership stakeholders.
• Experience helping teams sequence work, reduce uncertainty, avoid rework, and focus on the highest-leverage technical problems.

This position is onsite at our Menlo Park HQ . The salary will be adjusted to reflect local market conditions based on employee location as well as the experience of the employee. Along with base salary, Mainspring offers pre-IPO company equity through Restricted Stock Units (RSUs) + benefits.

Before you apply, a quick note on your resume
We care about the substance of your work and want to make sure we learn as much as we can about your design experience.  To help us evaluate your experience accurately, please ensure your resume includes:

• What you actually built or worked on — name the real product, subsystem, or hardware (not just "components" or "systems"). "Redesigned the bracket mounting the compressor to reduce vibration failures" tells us far more than "designed mechanical components."
• What you personally did , separate from what your team did. If you contributed to a group project, tell us your specific role and contribution.
• The engineering fundamentals you applied — tie your skills (CAD, FEA, GD&T, thermal/fluid analysis, testing, etc.) to the actual problem you used them on, rather than listing them as standalone skills.
• What happened as a result — did it pass validation/testing, resolve a failure, ship to production, and if so, at what volume or scale (prototype quantity, low-rate production, high-volume manufacturing)? This helps us understand whether your experience is with one-off/prototype hardware or product that shipped at scale.

One more thing: please don't feel obligated to keep your resume to one page. If accurately describing your relevant projects and contributions takes more space, that's completely fine — we'd rather see the detail than have you compress or omit meaningful work to fit a page limit.  

Thank You!

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.

We may use artificial intelligence (AI) tools to support parts of the hiring process, such as reviewing applications, analyzing resumes, or assessing responses and identifying potential inconsistencies or verification signals in application materials based on available information. These tools assist our recruitment team but do not replace human judgment. Final hiring decisions are ultimately made by humans. If you would like more information about how your data is processed, please contact us.