Image Number 4 for United States Patent #6039331.
The proposed crawler-mounted board (1) is specifically for the purpose of riding over grass or lawn slopes. It features a crawler unit which consists of two slightly concave-curved undercarriage tracks (12), the tracks being connected to one another by four cross-struts (13). The crawler unit can be mounted to a frame (2) made of tubing or rods. Each of the undercarriage tracks (12) consists of a long elongated body, a flexible crawler track chain, and large number of crawler track segments. A block can be mounted to the outside of each crawler track segment. While the crawler-mounted board is in motion, frictional forces act between the turf and the crawler track chains and the blocks of the crawler unit. These frictional forces cause the crawler track chains along with the crawler track segments to move around the body of the undercarriage tracks (12) in a closed circuit.