Coupling hook for a three-point connection on a tractor

A coupling hook for a guide member of a three-point attachment of a tractor comprising a hook member having a hook opening to receive a coupling pin on an implement and the like, said hook member having a pocket therein and there being a passage between said pocket and said hook opening, there being a slot in said pocket and a pivot element slidably received within said slot, an operating lever pivotally mounted on said pivot element and said pivot element being slidable in said slot when said operating lever is pivoted to a predetermined angle, a latch pivotally connected to said operating lever and having one end extending through said passage towards said hook opening, means defining a guide surface within said pocket and said latch having a first supporting surface pivotable and slidable on said guide surface, said latch having a second supporting surface engageable with an edge of said passage and said one end of said latch having an unlocking surface and a locking surface such that a coupling pin acting upon said latch unlocking surface during the coupling operation will slide said latch upon said guide surface into said pocket and when a coupling pin is locked within said hook opening said coupling pin acts upon said latch locking surface to urge said latch second supporting surface against said passage edge to produce a moment acting upon said latch and operating lever urging said latch into said hook opening.