Abstract: The lock has a rotatable latch. The latch is mounted for movement between a position wherein it engages a fixed part of the vehicle to secure the door in the closed position and a position remote from the fixed part of the vehicle such that the door can be opened. A latch movement preventing member is moveable relative to the latch between a position remote from the path of movement of the latch, wherein the latch is free to disengage the fixed part of the truck, and a position intersecting the path of the latch, wherein movement of the latch to disengage the fixed part of the truck is blocked. A pair of magnets are oriented to force the member to move from its remote position, against the action of a spring, to its intersecting position, to prevent the latch from disengaging the fixed part of the truck.

Abstract: The lock has a rotatable latch. The latch is mounted for movement between a position wherein it engages a fixed part of the vehicle to secure the door in the closed position and a position remote from the fixed part of the vehicle such that the door can be opened. A latch movement preventing member is moveable relative to the latch between a position remote from the path of movement of the latch, wherein the latch is free to disengage the fixed part of the truck, and a position intersecting the path of the latch, wherein movement of the latch to disengage the fixed part of the truck is blocked. A pair of magnets are oriented to force the member to move from its remote position, against the action of a spring, to its intersecting position, to prevent the latch from disengaging the fixed part of the truck.

Abstract: The security system determines if the cargo area of a vehicle may have been opened in transit between a loading location and a destination location. The vehicle has an enclosed cargo area with a cargo door and lock. The system includes a digital counter which displays a number set thereon after the cargo area has been secured by locking the cargo door lock or by closing the cargo door. If a magnetic reed switch senses the unlocking of the cargo door lock or the opening of the cargo door after the cargo area has been secured, it causes the number on the counter to change. The set number is forwarded to the destination location by entering it on the shipping documents or transmitting it electronically. At the destination location, it can be determined if the cargo area may have been accessed in transit by comparing the set number forwarded to the recipient by the shipper with the number displayed on the counter when the vehicle reaches the destination location.

Abstract: The truck security system emits an audible alarm when a cargo door is open and a driver or other person working on the truck goes beyond a defined distance, generally the immediate vicinity, from the truck exposing cargo to possible theft. In a truck having more than one cargo door, an alarm is sounded if more than one door is open simultaneously. If an attempt is made to start the engine with a door open, the system sounds an alarm in the cab and ignition is prevented. The system includes sensing means to detect if cargo doors are opened or closed, control logic circuitry and a clock, a RF signal receiver, an ignition cut-off, an audible alarm and a battery to independently power the security system, all of which are situated on the truck.

Abstract: A lock is provided for a vehicle having a door and a fixed part proximate the door. The lock includes a housing attached to the vehicle door. Latch means, including a hook, are mounted for rotation relative to the housing about an axis. The latch means rotates between a first position, wherein the hook engages a part of the vehicle to secure the door in the closed position, and a second position, wherein the hook is remote from the vehicle part such that the door can be opened. A latch rotation preventing member is moveable, relative to the housing, in a direction substantially parallel to the axis of rotation of the latch, between a forward position, remote from the path of movement of the latch means and a rear position, intersecting the path of the latch means to retain the latch means in its first position. Means are also provided for biasing the member toward the rear position.