Senior Mechanical Engineer

About Mainspring Mainspring Energy manufactures and delivers fuel-flexible, low-emissions local power solutions that rapidly add new capacity and deliver reliable, affordable, and sustainable electric power. The company began commercial shipments of its Mainspring Linear Generators in 2020 and today has hundreds of megawatts in advanced development and field operations for leading Fortune 500 companies, data centers, and utilities. Mainspring also partners with global energy leaders including AEP, NextEra Energy Resources, Schneider Electric, and more. The core values that ground our work, guide our decisions, and connect us together: Pragmatic Optimism Excellence without Ego Proactive Collaboration About the Role Mainspring is seeking a Senior Mechanical Engineer to own significant mechanical engineering projects, subsystems, or technical workstreams for our Linear Generator platform. In this role, you will develop robust mechanical designs, drive projects through the full design cycle, and work cross-functionally to validate and release hardware into production or field use. This role is intended for engineers who have already demonstrated independent ownership of meaningful mechanical design work through multiple design, test, release, or implementation cycles. A strong candidate should be able to own a significant subsystem or project area with limited day-to-day guidance, make sound technical tradeoffs, identify risks early, and drive cross-functional execution. Candidates who are still primarily building independence on bounded tasks or single workstreams may be better aligned to a Mechanical Engineer role, while candidates who regularly improve technical decision quality across multiple projects or teams may be better aligned to a Staff Mechanical Engineer role.