Abstract: Rear ends of pushing rods 40 are axially connected to a support base 50, which is movably engaged with guide rails 60. A drive unit 70 is disposed to rotatably move wire belts 74 between wheels 73 and 71 at longitudinal front and rear ends of the guide rails 60, and the support base 50 is connected to the wire belts 74. The drive unit 70 is activated to guide the pushing rods 40 by the guide rails 60 so to make pushing and pulling operation of the pushing rods 40. A door 33 which is disposed at the back wall of a static grate 31 in a clinker cooler 30 is opened to fit the pushing rods 40 into a seal material 34 on the opening to push a large lump of coating C2 retained on the static grate 31. The pushing rods 40 have a double tube structure and are cooled by injecting cooling water from supply pipes 45.