(2) The length of the left and right rods 7, 6 is adjusted, a shape easily controlled is selected from the moving loci of the shaft (control shaft 12) when the turning centers of the whole wheels are concentered and moved, and an inverted V-shape cam groove 21 matching with the shape is formed. (ロ)左右のロッド7,6の長さを調節して、全車輪の旋回中心を完全に一点に集中させて動かしたときの、軸(制御軸12)の移動軌跡より制御しやすい形を選択し、それに合致した逆V状のカム溝21を設ける。 - 特許庁