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Mainspring Energy is revolutionizing power generation with the world's most flexible and adaptable local power generation technology, the Mainspring Linear Generator. Commercial, industrial, and utility leaders are choosing Mainspring over traditional options like engines, turbines, and fuel cells to quickly and reliably deliver local power for EV charging, commercial facilities, data centers, and grid-scale operations. 

The Mainspring Linear Generator is fuel flexible, ramps up and down to meet demand, and utilizes a flameless reaction with near-zero NOx emissions. Backed by top-tier investors including Khosla Ventures, Bill Gates, American Electric Power, Lightrock, and General Catalyst Mainspring designs, manufactures and delivers its products to customers across the U.S. today, and we're quickly scaling for international expansion.

Inspired by our vision of the affordable, reliable, net-zero carbon grid, Mainspring is rapidly expanding within the $816B global electricity equipment market, and we're hiring the best talent to meet growing customer demand around the globe. We welcome a broad range of backgrounds, experiences, and talents to bring fresh perspectives and ongoing innovation to our customers.
We are looking to build relationships with people who share our values:
Pragmatic Optimism. Building a new category of world-class power generation requires the optimism of ambition and creativity, balanced with practicality to solve problems efficiently. The challenges that arise are opportunities for growth.
Excellence without Ego. We bring expertise and commitment to creating the best customer experience, from sales to deployment and service, just as we apply deep technical rigor to building and delivering world-class products. We strive for excellence and behave as leaders with the humility to acknowledge our challenges, both collectively and as individual contributors.
Proactive Collaboration. The integration and cross-disciplinary nature of Mainspring's business requires intentionally seeking out others who bring different skills, perspectives, and priorities. Our culture of inclusion and respect extends beyond our team to interactions with our partners and customers.
More information can be found at www.mainspringenergy.com

We are seeking a Director of Mechanical Engineering to lead a substantial portion of the team scaling the Linear Generator - a first-of-kind distributed power platform that converts a low-temperature, flameless reaction directly into electricity using high-frequency linear motion instead of rotating machinery. The system integrates reciprocating pressure-driven assemblies, air-spring return chambers, precision alignment systems, and linear electromagnetic machines within a modular 250 kW-class packaged unit. It operates under cyclic loads, tight sealing constraints, thermal gradients, structural dynamics, and grid-interactive performance requirements typical of commercial power generation equipment.

Reporting to the VP of Mechanical Engineering, this role is being created to expand leadership capacity, elevate risk visibility, and enable disciplined scaling of a growing hardware portfolio.

You will own ~40-50% of the mechanical organization's active projects and lead ~25 direct and indirect reports, with scope expected to grow. Your teams will oversee multiple core subsystems that are tightly coupled and reliability-critical.

Success requires both deep mechanical intuition and strong organizational leadership. You will strengthen technical rigor, improve prioritization across 50+ active efforts, and build execution systems that allow the organization to scale without sacrificing engineering excellence.

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 the base salary, Mainspring offers pre-IPO stock options + benefits.

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.