The frameless end dump fifth wheel trailer includes a cargo container. A rear axle and wheels support the rear portion of the cargo container. A hydraulic cylinder is pivotally attached to the front portion of the container. A piston rod of the hydraulic cylinder is pivotally attached to a kingpin plate assembly. A kingpin is secured to the plate assembly. A tension frame assembly is pivotally attached to the plate assembly and to the center portion of the container. Two mast members are secured to the plate assembly. A pair of kingpin plate control arms have forward ends each of which is pivotally attached to one of the masts and rear ends pivotally attached to the center portion of the cargo container. A flat bottom surface of the kingpin plate is held in a substantially horizontal position by the plate control arms.