Movement control for pickup-mounted vehicle

Claim 1

A movement limiting device to dampen forces generated by two members movable relatively toward and from each other, one said member comprising the cab of a wheel-mounted vehicle having a bed located rearwardly of said cab, and the other said member comprising a forwardly directed extension of a camper mounted on said bed, said extension being above and spaced from said cab, said device comprising: a. a pivotal connection provided on a side of the cab member, b. a second pivotal connection provided on the extension member of the camper and in generally longitudinal alignment with the first mentioned pivotal connection, both said pivotal connections having axes substantially perpendicular to the fore and aft center line of said vehicle, c. a cylinder defining a chamber closed at one end and having an opening in the other, said cylinder being directly connected at its closed end to the pivotal connection of one of said two members, d. a piston in said chamber with a stem extending through the mentioned opening and directly connected to the pivotal connection of the other of said two members, e. hydraulic fluid filling the chamber on both sides of the piston, f. and shock absorbing means in the cylinder acting in both endwise directions of movement of said piston, said shock absorbing means comprising at least two poppet valves carried by the piston, one poppet valve being arranged to open for bypass flow of fluid from one end of said chamber to the opposite end when the cylinder and piston are moved relatively toward each other, and the other poppet valve being arranged to open for bypass flow of fluid from said opposite end of the chamber to said one end when the cylinder and piston are moved relatively away from each other, g. each said poppet valve having a passage extending through the piston from one end of said passage to the other end of said passage, said passage having a first cylindrical portion adjacent said one end of relatively larger diameter and a second cylindrical portion adjacent said other end of relatively small diameter, h. a poppet body in said passage having a guiding end slidably mounted in said first cylindrical portion and a restricting end slidably mounted in said second cylindrical portion to flow during movement of said restricting end between opposite ends of said second cylindrical portion, i. bypass means extending between said restricting end and the opposite end of said poppet body, and j. a resilient bias acting between said poppet body and said piston body to hold said poppet body in normal flow restricting position and yielding to pressure of hydraulic fluid being displaced by relative movement of the cylinder and piston to move said poppet body to open position whereby to extablish flow through the bypass means whereby to inhibit operation of the shock absorbing means for shock of magnitude insufficient to move said restricting end out of engagement with said second cylindrical portion.