Shellable child resistant closure container with positive lock mechanism

A closure system for a container having a neck with an engaging device, said closure system including:

• a. a cap having a top wall with an upper, outside surface and a circumferential side wall depending from said top wall, said side wall having an inside surface and an outside surface;
• b. an engaging device on the inside surface of said side wall for cooperatively engaging an engaging device on a container;
• c. a series of angular abutments on said cap designed to allow a cam follower to cam over said abutments when a cam follower is moved in one direction and to engage a cam follower moved in another direction;
• d. a groove in said outside surface of said circumferential side wall, and
• e. a channel in said outside surface of said circumferential side wall, said channel running from said groove to the upper, outside surface of the top of said cap;
• whereby said cap can serve as a non-childproof closure for a container, but can be made childproof by the addition of a second cap to the closure system.

A cap for use in conjunction with a closure system for a container and designed to make the closure system child proof, said cap including:

• a. a top wall having an outer top surface and an inner underside surface;
• b. a circumferential sidewall depending from said top wall, said circumferential sidewall having an inside surface and outside surface;
• c. a series of angular abutments on said underside surface of said top wall, said angular abutments designed to serve as cam followers for cooperative engagement with a series of angular abutments on a closure cap;
• d. at least two tabs on the inner surface of said circumferential sidewall, said tabs designed, shaped and positioned to engage a grove in the closure cap when said cap is placed in nesting relationship over the outside of the closure cap;
• and
• e. said tabs shaped to pass through a channel in the closure cap when one of said tabs is aligned with such a channel and allow separation of said cap relative to the closure cap.