Abstract: A cutting machine for cutting trenches in the ground, including a flat bottom face portion for supporting a pair of motor blocks; two motor blocks, with parallel axes, adapted to mount half-drum cutters; each motor block comprising a central vertical keel projecting downwardly from a horizontal top plate; connection means securing each motor block top plate to said bottom face; the inner edge of each top plate being provided with a beveled surface; an abutment member having parallel beveled edges complementary in shape to the beveled edge of each top plate; means mounting said abutment member to the central portions of said bottom surface; locking means urging the beveled edge of each top plate against the beveled edges of said abutment member.