Security system for cargo trailers

A cargo transportation device has a container including a cargo door accessible from the outside for closing the container and being movable from an open position to a closed position. A security system is provided that includes a latching device on the inside of the container, the latching device having a latch, a screw for moving the latch between an open position and a closed position, and a rotary motor for turning the screw. The security system has a latch receiving device, adapted to receive the latch, on the inside of the container. A controller operates a motor to turn a screw in one direction and thereby moves the latch from its unlocked position to its locked position. The controller also can operate the motor to turn the screw in the direction opposite of said one direction thereby moving the latch from its locked position in the latch receiving device to its unlocked position.