Lock mechanism

A lock mechanism comprising

• a. a hollow cylindrical housing having an outer surface, an inner surface and at least one longitudinal groove cut into its inner surface,
• b. a face plate having a key hole therein and attached to one end of the housing,
• c. a cylinder having a longitudinal keyway and inserted into the housing, so that the keyway is aligned with the key hole,
• d. an endpiece having a face and attached at its face to the housing opposite the face plate and having at least one circumferential groove and at least one radial groove cut in its face,
• e. four tumblers
• (i) pivotably mounted at approximately 90.degree. intervals to the cylinder on an axis transverse the cylinder,
• (ii) having a locking edge sized and positioned so as to extend into the longitudinal groove in the housing when the tumbler is in a locked position, and to be within the cylinder when the tumbler is in an unlocked position,
• (iii) having at least one tab sized and positioned so as to fit within a radial groove of the endpiece when the tumbler is in a locked position and to align with and be capable of traveling through a circumferential groove in the endpiece when the tumbler is in an unlocked position, and
• (iv) having a keying edge which has a given slope relative to a center line through the keyway and which extends into the keyway, said tumblers being sized and positioned to be able to pivot from a locked position to an unlocked position;
• and
• f. a resilient means attached to the tumbler to bias the tumbler toward a locked position.