Self-adjusting shock absorber having staged metering

A shock absorber for decelerating objects impinging thereagainst, said shock absorber being of the type comprising a hydraulic cylinder, a piston in said cylinder and having a predetermined stroke therein from a first position adjacent one end of the cylinder to a second position adjacent the other end of the cylinder, a piston rod extending externally of said cylinder from said piston, means resiliently biasing said piston to said first position, a hydraulic reservoir and fluid passageway means from the cylinder to the reservoir through which the hydraulic fluid in the cylinder flows to the reservoir when the piston moves toward the second position in response to a shock force to be absorbed being applied to the piston, said passageway means having orifice means therein for controlling the rate of flow of hydraulic fluid to the reservoir and thereby establishing the resistance of the shock absorber to shock forces, said orifice means providing different rates of flow for different parts of the stroke of the piston as it moves from said first position to said second position, said shock absorber being subjected to shock forces consisting of a plurality of different equivalent mass systems including a maximum mass system and a minimum mass system, said shock absorber being characterized by:

• said orifice means establishing a rate of flow to the reservoir, for an initial part of said stroke as said piston moves away from said first position, such that there is a constant deceleration of the object associated with the minimum mass system during said initial part of the stroke, and establishing a rate of flow to the reservoir, for a final part of said stroke as said piston moves to the second position, such that there is a constant deceleration of the object associated with the maximum mass system during said final part of the stroke.