Impact absorbing device for protecting vehicle's occupant from impact caused by collision

In a vehicle seat structure including a seat mounting having a first portion for securing to the vehicle, and a second portion to which a seat may be secured, said second portion being relatively movable with respect to said first portion along the direction of movement of the vehicle, the improvement which comprises:

• (i) said first and second seat mounting portions each include a respective rail extending in the direction of movement, said rails being engaged one with the other for relative sliding movement of the seat mounting portions guided along the direction of movement,
• (ii) one of said rails provides a plastically deformable deformation member,
• (iii) die means are secured to the other of said rails, said deformation member and said die means being positioned for engagement one with the other such that, when said second portion moves with respect to said first portion, said die means progressively deforms said deformation member for the absorbtion of kinetic energy resulting from deceleration of the seat structure, and
• (iv) means are provided for releasably locating said second seat mounting portion with respect to said first seat mounting portion, said locating means including a rod having at spaced positions thereon a pair of dies positioned for engagement with said deformation member and constituting said die means, and means carried by the other of said seat mounting portions and movable into and out of locking engagement with said rod at selected positions along said rod.