Motor vehicle security system and security method

Claim 1

A motor vehicle security system for a motor vehicle comprising a motor vehicle having a plurality of wheels, a source of pressurized air, separate braking assemblies for each of a plurality of wheels each adapted to be activated to a braking position, pneumatic control means coupled to the source of pressurized air for controllably activating the braking assemblies, the braking assemblies including mechanically powered alternate brake setting means coupled to the source of pressurized air and maintained in a de-actuated brake setting condition in response to the application of pressurized air thereto and automatically activated to a brake setting position in response to the loss of pressurized air below a predetermined level, and a lockable three way valve means coupled in series with the source of pressurized air and the mechanical brake setting means for controlling the application of pressurized air thereto and thereby the braking condition of the braking assembly, the mechanically powered brake setting means being a spring powered brake setting means constructed and defined to allow manual resetting of the spring powered brake setting means at said brake means, said spring powered brake setting means including means for preventing the manual resetting of the spring powered brake setting means at said brake means to prevent unauthorized operation of the braking assemblies when the lockable valve means is in the locked brake setting position, the lockable valve means being manually operable to a locked condition for producing a brake setting operation and thereby render said control system inoperative and manually operated to an unlocked condition for allowing the controllable and automatic setting of the brakes without interference with the normal operation of the control system therefor.