Patent ID: 8641074

Claim:
A coupling apparatus for a grain trailer comprising an upper subframe fixed to the underside of a frame of the grain trailer, the upper subframe including a pivot support secured thereto, the pivot support comprising first and second spaced apart bearing support plates, a lower plate member pivotably retained to the upper subframe, the lower plate member comprising a kingpin depending therefrom, a pair of spaced apart axle receivers fixed to and extending above a skid plate of the lower plate, an axle passing through the axle receivers of the lower plate and also through bearings supported in the bearing support plates of the upper subframe, the pivot support secured to the upper subframe between a front end wall and an intermediate rib of the subframe, the first bearing support plate depending from the front end wall of the upper subframe and the second bearing support plate depending from the intermediate rib of the upper subframe, wherein the lower plate will rock about the axle relative to the upper subframe.