This particular coupler dates right back to the "trailer boom" era of the mid-to-late 1930s or early 1940s.
The Design: Before standardized modern trailer couplers took over, companies like Fulton engineered heavy, cast-iron clamping couplers. This unique design features a star-crested "helmet" shape on the clamping jaw and a hand-crank flower/star knob meant to tightly clamp down on an early style trailer ball.
The Stamping: The text reads "Patent Apld. For" (Patent Applied For), indicating this was manufactured early in this specific model's production run before the official patent was granted.
