Articulation joint roll stabilizer

Claim 1

An articulated wheeled vehicle comprising a tractor; a trailer; a first hitch fitting (14) carried by the tractor at its rear end; circular bearing means (32) carried by the trailer front end, said bearing means extending along the trailer longitudinal centerline to define a trailer roll plane axis; a second hitch fitting (40) swingable on said bearing means in the trailer roll plane; said second hitch fitting including two laterally spaced arms (42) extending forwardly from the trailer toward the first hitch fitting; hinge pin means (44) connecting the second hitch fitting spaced arms to the first hitch fitting; said hinge pin means extending along a horizontal axis transverse to the tractor longitudinal axis in intersecting relationship to the aforementioned trailer roll plane axis, whereby the hinge pin means defines a tractor-trailer pitch plane axis; hydraulic means for introducing mechanical resistance to motion of the trailer in the roll plane; said hydraulic means comprising a closed hydraulic circuit that includes at least one hydraulic piston-cylinder mechanism trained between the trailer and the second hitch fitting, said piston-cylinder mechanism defining two piston-cylinder chambers of inversely-varying volume; a fluid line (52, 56) interconnecting the two chambers; and a solenoid valve (54) in said fluid line; said valve having a first substantially closed condition offering substantial resistance to liquid flow through the fluid line, and a second open condition offering minimum resistance to liquid flow through the fluid line.