A forward and rearward support assembly each have a vertical fixed post with upper and intermediate apertures and a pair of vertical reciprocable posts with upper and lower and intermediate apertures. Each support assembly has an upper and a lower oscillating plate. Each plate has an upper aperture. An upper pivot pin extends there through and through the apertures of the fixed posts. Each plate has a pair of laterally aligned lower apertures. Each plate has lower pivot pins. The lower pivot pins extend there through and through intermediate and lower apertures of the reciprocable posts. A forward and a rearward cradle and pivot pins couple the cradles and upper apertures of the reciprocable posts.