Senior Staff Mechanical Engineer - Structures & Alignment

Mainspring Energy•Menlo Park, CA

3d•$170,000 - $209,000•Onsite

About The Position

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. 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 its 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 it 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.

Requirements

Degree in Mechanical Engineering or a similar engineering field from an accredited institution. Experience and degree will determine level, but minimum requirements are: BS + 12 years experience or MS + 10 years experience
Delivered products as a technical lead through 3+ full design lifecycles from concept to manufacturing support, preferably with product in high vibration environments with large cyclic loading
Expertise in bolted joints, thermal impact on structures, design and analysis for severe vibration environments a big plus
Fluent in SolidWorks or comparable CAD package. Experience with using PDM or a similar CAD version control system is preferred
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 creating a more sustainable world

Nice To Haves

Experience with using PDM or a similar CAD version control system is preferred

Responsibilities

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 (SolidWorks) 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