Abstract: A tractor trailer anti-jackknifing system for preventing a trailer from jackknifing when coupled to a tractor. The tractor trailer anti-jackknifing system includes a hitch plate designed for mounting to a tractor with a center hole for receiving a kingpin of a trailer therein and an arcuate first pin slot. The system also includes a bottom plate designed for mounting to the trailer. The bottom plate has a kingpin hole designed for extending the kingpin of the trailer therethrough and an arcuate second pin slot. A fluidic piston-cylinder actuator is mounted to the hitch plate beneath the first pin slot of the hitch plate. The fluidic piston-cylinder actuator has a cylinder portion and a piston portion retractably extendable from the cylinder portion. The piston portion is extended into the first pin slot of the hitch plate. The piston portion is extendable to an extended position where the piston portion upwards extends into the second pin slot of the bottom plate.