A seatback fitting assembly is provided with means to allow the complete forward rotation of the seatback, while remaining anchored to the seat structure, upon an excessive dynamic load or force impact on the seatback. This is accomplished by the use of a structural "breakover" device operating within the fitting assembly, which restrains the seatback within a limited, "forward tilt" range of motion under normal conditions, but allows complete forward rotation once load forces above an allowable level act on the seatback to cause a restraining pin to shear. A friction brake or clutch arrangement is provided to inhibit tilting of the seatback at all times but does not prevent the complete forward rotation of the seatback.

In the event of a rear end collision the headrest of a vehicle seat is moved from a normal initial position to a position approximate to the vehicle occupant's head under the effect of inertial forces occurring at a mass coupled to the headrest, thereby reducing the distance between the vehicle occupant's head and the headrest.

A vehicle seat assembly is provided with an energy absorption mechanism for dissipating energy in a high energy impact. The assembly includes a seat with a seat back totally connected thereto. The seat back includes a first support member pivotally connected with respect to the seat and a second support member pivotally connected to the first support member. An energy absorption mechanism is positioned between the first and second support members for dissipating energy as the second support member pivots with respect to the first support member. The energy absorption mechanism includes a plurality of adjustable shear pins having shearable cross-sections of various sizes to facilitate adjustment based upon the seat back angle. The shear pins are movable in a plurality of slots sequentially increasing in length such that the shear pins will sequentially shear to dissipate energy over time as the respective shear pins reach the end of their respective slots.