Senior Mechanical Engineer - Structures & Alignment

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 such as 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 an affordable, reliable net‑zero carbon grid, Mainspring is rapidly expanding within the $816 B global electricity equipment market. We’re hiring the best talent to meet growing customer demand worldwide. 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
, Excellence without Ego
, and Proactive Collaboration
.

Mainspring’s Linear Generator is fundamentally different from a traditional engine. Instead of rotary motion and a crankshaft, our system converts linear oscillation directly into electricity. A low‑temperature, flameless reaction accelerates pistons and their translator shaft, wrapped with permanent magnets, through stator coils. Air‑spring chambers reverse the motion, generating power with high efficiency and ultra‑low emissions.

Critically, the translator shaft and pistons float on precision air bearings, riding on a thin film of pressurized air. This minimizes friction and wear but also removes rigid mechanical constraints. The translator must remain precisely aligned within tight tolerances across the full cylinder length while traveling at resonance under dynamic loads. This architecture is elegant—and mechanically unforgiving.

• Lead structural design and alignment strategy for alignment‑critical components
• Design and validate bolted joints under cyclic and thermal loading
• Develop GD&T and tolerance stack strategies across subsystem interfaces
• Own 3D CAD (Solid Works) and structural FEA (ANSYS or equivalent)
• Model structural behavior under vibration and thermal gradients
• Plan and execute durability testing and structured root‑cause investigations
• Translate test and field data into improved design standards
• Partner with Electrical, Controls, and Manufacturing teams to ensure scalable robustness

• Degree in Mechanical Engineering or a similar engineering field from an accredited institution.
  
  Minimum requirements:
  
  BS + 12 years experience or MS + 10 years experience.
• Delivered products as a technical lead through 3+ full design life cycles from concept to manufacturing support, preferably with a product in high‑vibration environments with large cyclic loading.
• Expertise in bolted joints, thermal impact on structures, and design and analysis for severe vibration environments is a big plus.
• Fluent in Solid Works or a comparable CAD package. Preference for experience with a PDM or a similar CAD version control system.
• Hands‑on mechanical prototyping, assembly, testing skills, and experience with mechanical engineering analysis tools (FEA, CFD, thermal analysis, tolerance stack‑ups).
• Deep understanding and knowledge of mechanical design principles, materials, manufacturing processes (sheet metal, welding, casting), and ability to identify and resolve design for manufacturability issues.
• Excellent problem‑solving, creative thinking, communication, and collaboration skills for effective cross‑functional teamwork.
• Ability to work independently, manage multiple projects in a fast‑paced environment, and demonstrate leadership and mentoring abilities.
• Passion for clean energy and commitment to…