Compression Spring 0.396" ID 0.48" OD

The small return spring that lives inside Flow’s electronic shift sensor stack on Classic/ESL 55k and 60kpsi intensifiers (and the later 87 k HyperJet variant). When the piston reaches the end of stroke, the spring forces the firing pin / actuator plunger back against the proximity sensor so the shift‑module sees a crisp “home” signal and the pump reverses cleanly, keeping line pressure rock steady and prolonging check valve life.

Replace the A‑2409 spring every time you remove the shift sensor or every 500 hour minor service. A new spring restores factory preload, prevents hesitation at stroke reversal, and helps your Flow intensifier maintain smooth pressure and long seal life.