Senior Mechanical Engineer - Electromechanical

Company Overview

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

Mainspring is seeking Sr. Staff Mechanical Engineers with a focus on designing electrical enclosures and cables while improving functionality and system‑level performance. This role will involve not only owning engineering development projects but also taking a leadership role in guiding technical decisions and influencing the design process across teams. You will work with cross‑functional teams to ensure that key electrical and mechanical subsystems meet challenging technical requirements from concept through manufacturing launch.

You will directly manage engineers, providing leadership while ensuring that all team members work towards a cohesive project goal. Ideal candidates will have a strong combination of technical expertise, leadership abilities, and the drive to solve complex problems in a collaborative environment.

• Lead ideation and design reviews to develop innovative solutions that enhance performance and reduce cost of the Linear Generator and its electrical subsystems
• Own the structure, layout, optimization, prototyping, testing, and deployment of electrical enclosures and harnesses
• Partner with Electrical, Reliability, Test, NPI, Manufacturing, and supplier teams to define design direction, validate solutions, and meet project milestones
• Oversee execution by setting requirements and coordinating across disciplines to maintain cohesive technical direction
• Manage and mentor engineers, guiding technical decisions, setting priorities, and supporting professional growth
• Proactively balance timelines, resources, and risks to ensure consistent delivery on key engineering initiatives

• Degree: BS or MS in Mechanical, Electrical, or related engineering field with 11 years of industry experience
• Proven ownership of electrical enclosure and cable designs, with experience influencing cross‑functional teams
• Deep expertise in sheet metal,…