Wiktionary
unbrake
vb. 1 (context intransitive English) to stop braking, to release the brake(s) 2 (context transitive English) to release the brakes of (a car, wheel)
Usage examples of "unbrake".
Sanner unwound the last loop of his rope, levered out the piton it had been lashed to, and did an unbraked slide down the rest of the way to the bottom.
Like an unbraked millwheel caught in an inconceivable flood, Bloodstone was snared in a vortex of energy that raced out of control, pent up with no outlet, raging power that would tear it to atoms.
For a moment, I had the fleeting paranoid fear that they had recognized us and deemed to eliminate us simply by letting us smash unbraked into the unyielding earth of Cantwell, Alaska.