PURPOSE: To prevent an elastic body from exfoliation and enable to eject muddy water, soil, etc., by setting a distance between the non-ground contacting surface side of a shoe plate and left and right shoe links larger than the thickness dimension of the elastic body on the non-ground contacting surface and molding the elastic body integrally from the left and right outer sides of the left and right shoe links to the inner sides.

CONSTITUTION: A distance H between the non-ground contacting surface 3 of a shoe plate and left and right shoe links 5 is set larger than the thickness dimension T of an elastic body 7 to form a gap 14 between the shoe links 6 and the surface of the elastic body 7. The gap 14 affords communication between the inside and outside in the left and right of the left and right shoe links 5 to enable the ejection of muddy water and soil inside the shoe link 5. Also, the elastic body 7 covering the non-ground contacting surface 3 of the shoe plate 2 is formed continuously from a ground contacting surface 6 to the periphery of the shoe plate 2 to be integrally molded except for the mounting part 4. As a result, the elastic body 7 does not have the left and right ends, so that it is not exfoliated even by receiving a thrust force and prevents the non-ground contacting surface from rusting.