In the Clapham Junction plant, four upright shafts on each side of the track carry a number of strips of cloth. These shafts are rotated, and the cloth strips fly outwards, gently lapping the sides of the carriages. Copious showers of water are simultaneously sprayed on to the cloths and train, removing every speck of dirt. The eight revolving shafts are supported by a structure consisting of steel columns, longitudinal and cross-girders braced together. These also support electric motors and driving gear overhead, as well as a system of vertical and horizontal spray pipes. The whole is housed in a steel frame building covered with corrugated sheeting. The plants are controlled from small cabins adjacent to the machines containing the switch-gear and pumping machinery. In addition, push buttons on each end of the machines enable them to be stopped at will by the operator.