This set of worm wheel gear which was used in boat . Material 34CrNiMo6 for worm shaft ,heat treatment : carburization 58-62HRC . Worm gear material CuSn12Pb1 Tin Bronze . A worm wheel gear, also known as a worm gear, is a type of gear system commonly used in boats. It is made up of a cylindrical worm (also known as a screw) and a worm wheel, which is a cylindrical gear with teeth cut in a helical pattern. The worm gear meshes with the worm, creating a smooth and quiet transmission of power from the input shaft to the output shaft.