Senior Mechanical Engineer - Frame and Air

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 Energy is seeking a talented Mechanical Engineer to join the team responsible for the design and development of the frame support structure and air spring system for our innovative Linear Generator technology. These systems are critical for maintaining our very tight alignment of subassemblies, withstanding significant structural and thermal loads during operation, and storing potential energy during part of our cycle.

This is a challenging, hands‑on role where your creativity, strong engineering fundamentals, and practical skills will directly contribute to making a significant impact on our clean energy solution.

• Lead design and development of frame and air spring subsystem projects, including conceptualization, detailed design, 3D CAD modeling (Solidworks), engineering analysis (FEA/CFD tools like ANSYS for thermal, structural, and flow), testing, root cause investigation, and comprehensive documentation.
• Focus on challenges specific to our frame structure and air spring systems, such as achieving and maintaining a very tight alignment, design for high load transfer and fatigue durability, design for thermal management and improving system performance.
• Collaborate effectively with cross‑functional teams (Controls, Manufacturing, Suppliers) to ensure seamless subsystem integration, performance, and support new product introduction (DFM/DFA, work instructions, tooling/fixtures).
• Plan and execute rigorous verification and validation testing to ensure designs meet demanding requirements (functional, durability, thermal, vibration, acoustic, safety, reliability).
• Support the continuous improvement of engineering processes, tools, standards, and best practices within the team. Provide technical guidance to junior engineers and technicians.
• Stay current on advancements in mechanical engineering relevant to power…