Rapping gears are mainly employed in horizontal boiler sections on garbage waste incineration plants. These gears serve to clean suspended evaporators, superheaters and economizer tubes by means of rapping.

Rapping is applied mechanically on the strengthened surface of horizontally arranged headers. The impact energy sets the vertically suspended heating surfaces into vibration. Thus removing the deposits.

The impact energy can be produced by mechanically actuated hammers or by pneumatically actuated rapping cylinders. The pneumatic rapping gears have an electrically driven positioning carriage which positioning the rapping cylinder in line with the rapping points.