PURPOSE: To eliminate plugging due to muck by steepening a gradient for positive muck transfer in a conveyor on a muck-loading machine, and by shortening length of the conveyor for compactness, and by eliminating relative movement with muck for less wear of the conveyor.

CONSTITUTION: A dish-like bucket 21 is securely bolted to the inside surface of each link 12 of a roller chain driven by means of a sprocket. Each bucket at its one side is formed as a circular curved part 21a with the shaft 18 of a roller 17 as center of curvature. The other side is similarly formed as a circular curved part 21b. In transferring muck, the curved part 21a at the bucket one side covers the curved part 21b at the adjoining bucket other side. In circumferentially turning the sprocket, the curved parts are turned with the shaft 18 as center to prevent opening between the curved parts.