Do you have the brush hog attached and rigged correctly? If you are supporting the full weight of the hog by the hitch you will need to counter its weight. The hog should be floating, that is, drag arms supporting the hog and the tail wheel on the ground at all times. The top link should be relaxed to allow the hog to follow the contour of the ground. The only time when the full weight of the hog is on the hitch is when the hog is lifted for transportation.