| 摘要 |
PURPOSE:To obtain a superior driving force and improved durability by forming the top face of a lug free from deformation in uneven form. CONSTITUTION:As the center lug part 11 has the concave 17 close to an engaging hole 6, sure engagement of a driving wheel with a sprocket clutch can be obtained, and stable traveling is permitted. On the concave part 17, only the lug kicking face 15 or the opposite surface 16 is concaved and the top face of the lug is not concaved, so the top face 14 of the lug can be formed into free shape, and the width of the top face 14 of the lug is formed into the band shape free from variation in uneven form in the part from the center lug part 11 to the side lug part 12, so the impact on grounding through trailing wheels can be dispersed and reduced over the whole lug. |
