Senior Mechanical Engineer - Frame and Air Spring

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 www.mainspringenergy.com Senior Mechanical Engineer - Frame and Air Spring 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. 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. Core Responsibilities 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 generation, identifying opportunities to reduce costs, improve performance, and enhance reliability as Mainspring scales its technology Uphold and further Mainspring's mission to create clean, affordable, and reliable power generation that accelerates the world's transition to a sustainable energy future. Qualifications Bachelor's degree in Mechanical Engineering or similar field. 6+ years as a professional mechanical design engineer. Delivered products through 2+ full design lifecycles from concept to manufacturing support, preferably involving industrial equipment, power generation, engine systems, or similar demanding applications. Self-starter with a proven ability to deliver functional designs in a rapid development environment and a track record of innovation and continuous improvement. Direct experience designing components or systems operating in high-cycle and high-load environments. Demonstrated engineering fundamentals in structural mechanics and thermal design. Experience with structural analysis (FEA) is essential. Direct experience designing systems with bolted joints that carry load. Demonstrable experience in taking ownership of projects, setting requirements, managing complex technical decisions, identifying and addressing potential risks and driving decisions to meet competing technical and functional requirements Familiarity with design considerations for durability, fatigue, and reliability in demanding applications. Proficiency in 3D CAD modeling (Solidworks preferred), engineering drawing creation (GD&T, detailed datum selection), and experience with PDM or similar CAD version control system. Knowledge of mechanical design principles, materials, manufacturing processes (machining, sheet metal, welding, casting, forging), and ability to identify and resolve design for manufacturability issues. Hands-on mechanical prototyping, assembly, and testing skills. Experience with relevant instrumentation (thermocouples, accelerometers, pressure sensors) is a plus. Experience applying engineering analysis tools (FEA, tolerance stack ups) to solve design problems and validate concepts. Familiarity with acoustic analysis is beneficial. Excellent problem-solving, creative thinking, communication, and collaboration skills for effective cross-functional teamwork. Ability to work independently and manage multiple projects in a fast-paced environment. Passion for clean energy and commitment to creating a more sustainable world.

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