Symbol 3414 from ISO 7000 - Title/Meaning: Engine rotational speed, automatic increase Function/description: To identify the control that automatically increases the engine rotational speed.
pay attention to orientation of symbolAdditional information: 
Fonts shown are not restrictive.
Own work using: iso.org/obp/graphics/grs/ebbe3371-3bca-47ee-ad68-a2ac94c2274e 200.png
Vectorization:  Mrmw