Abstract: A remotely activated electro mechanical device is mounted in the dual chamber brake system of a vehicle or trailer. The device includes a solenoid valve and a receiver decoder which controls the valve in response to a coded signal ideally available only to law enforcement to vent pressure in the emergency chamber of a dual chamber brake system to automatically apply the brakes thereby bringing a moving vehicle to a stop. The device is also responsive to a second, different coded signal, available only to authorized users to vent pressure in the emergency chamber and to lock the brakes by preventing pressurized air from being supplied to the dual chamber brake system of a stopped or parked vehicle. The device is also responsive to coded signals which reverse the above-noted actions.

Abstract: In a theft deterrent security device for trailers and like equipment having a dual chamber brake system that operates with compressed air an electro mechanical device, such as servomotor or a solenoid, is mounted within the interior of the dual chamber brake system housing in which an expanded high spring-rate spring biases and keeps a brake actuator in a locked “brakes on” position when there is no compressed air supplied to the system. The servo motor or solenoid is connected to members which in one position mechanically block movement of the brake actuator to prevent its normal operation even when there is compressed air available to the system and the high spring-rate spring is compressed. In a second position of the servo motor or solenoid the members do not block movement of the brake actuator and thereby allow normal operation of the brakes. The servo motor or solenoid is responsive to coded signals which control its position and which are normally available only to an authorized user.