What is "declutching"

Usage examples of "declutching".

She drove like a man very fast but skilfully, picking a tight line into the corners and using the gearbox to brake, double declutching with dancing feet on the pedals, and hitting the shift with a quick sure hand, Beside her the General sat with the set to his shoulders of a younger man.

Good, he thought dispassionately, applauding the choice, and he hit the gear lever of the Rolls, double declutching into a lower gear to build up revolutions for the turn.

Indeed, the choice was made for me by my ignorance and indecision: I braked without either declutching or closing the throttle, and the motor stalled.