Semi-trailer locking apparatus

A locking apparatus for locking at least one door of a semi-trailer or freight delivery unit, the semi-trailer or freight delivery unit having a floor, the locking apparatus comprising:

• (a) a housing inserted through the floor and secured therein, the housing having an inner wall;
• (b) a plate having a channel therein and positioned on the door of the semi-trailer adjacent to the housing when the door is closed;
• (c) a pin mechanism located within the housing and being of a diameter less than the inner wall of the housing, and capable of moving from an unlocked retracted position where the pin mechanism does not engage the plate, to a locked position where the pin mechanism engages the plate such that the door can not be opened;
• (d) wherein the pin mechanism has at least one stop collar located approximately mid-point along the length of the pin mechanism, the locking apparatus further comprising:
• (i) a pin guide positioned towards the top of the housing, said pin guide having a bore of sufficient diamater to permit passage of the pin mechanism but not the stop collar;
• (ii) an inner pin guide positioned towards the bottom of the housing, said pin guide having a bore of sufficient diamater to permit passage of the pin mechanism but not the stop collar;
• and
• a cam lock, said cam lock being inserted in the bottom of the housing until the cam lock reaches the inner pin guide, said cam lock having a cam which engages a groove immediately below the inner pin guide.