This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
PORV closed piston. PORVclosedpiston svg PORVclosedpiston svg en August author Slightlymighty image missing spring how is it reset No internals in control pilot not shown there would be spring there en Zerodamage CommonsHelper Slightlymighty en en Slightlymighty Original upload log en PORVclosedpiston Slightlymighty bytes