A child-resistant screw-on closure for use on a container having a threaded portion threadedly engageable with the screw-on closure, the closure having a closure-state indicating pattern, comprising:
- an inner cap having a circular top wall portion and a cylindrical skirt depending from the top wall portion, the inner surface of the skirt being threaded for threaded engagement with the container when the inner cap is rotated in a closing direction and disengageable therefrom when the inner cap is rotated in an opening direction;
- a middle cap having a circular top wall portion and a cylindrical skirt coaxial with and peripherally surrounding the cylindrical skirt portion of the inner cap, said middle cap being axially displaceable relative to said inner cap, a cam surface having a front end and a trailing end along the circumference of the outer skirt of said middle cap as said middle cap is rotated in the closing direction with the front end being at a greater radial distance from the center than the trailing end, an indicating pattern and a raised stopped on said cylindrical skirt of said middle cap and
- an outer cap arranged for rotation relative to the middle and inner caps and having a circular top, a cylindrical skirt coaxial with and peripherally surrounding the skirt of the middle cap, a window, means for frictional engagement with said camming surface of said middle cap providing a progressively increasing frictional engagement between said middle and outer caps as said outer cap is rotated in said closing direction so that the outer cap first rotates relative to said middle cap until said frictional engagement means frictionally engages the camming surface of the middle cap to transmit torque thereto, thereby causing the middle cap to rotate together with the outer cap;
- and one-way torque transmitting means connecting said middle cap to said inner cap to cause them to rotate together in the closing direction and to prevent concurrent rotation of said inner and middle caps in the opening direction in the absence of the application of axial force thereto, whereby rotation in the closing direction of the outer cap will cause like rotation of said middle and inner caps so that, the threaded portion of the inner cap seals the threaded portion of the container, and thereafter, the outer cap moves relative to the middle and inner caps causing said means for frictional engagement to ride on said cam surface of the middle cap increasing said frictional engagement so that said indicating pattern on the middle cap is viewable through said window on the outer cap and, conversely, when the outer cap is rotated in said opening direction with the use of both rotational and axial force to open the container, the outer cap first moves relative to the inner cap allowing said indicating pattern on the middle cap to be viewable through the window on the outer cap and secondly abuts said raised stopper wherein the closure is disengaged from said container.