Abstract: A vehicle anti-theft device which maintains the braking function of the braking fluid by preventing reverse flow thereof from the wheel cylinder back to the master cylinder until, following an authorized procedure, an interconnecting fluid passage is moved into a strategic position which allows this reverse flow. As an improvement over the prior art, the direction of application of the braking fluid is arranged to assist, rather than impede, the strategic positioning of the aforesaid interconnecting fluid passages as well as contribute to other noteworthy advantages in the operation of the within device.

Abstract: A vehicle anti-theft device which maintains the braking function of the braking fluid by preventing reverse flow thereof through a closed main valve opening from the wheel cylinder back to the master cylinder until, following an authorized procedure, the main valve opening is cleared. As an improvement over the prior art, the main valve opening is closed manually by a member being seated therein, and this member is then held in place under pressure, the member, however, having an internal pressure-releasing valve for releasing the "holding pressure" when it is necessary to move the member into a clearance position off of the valve opening.