Scanners are available that pull a flat sheet over the scanning element between rotating rollers. The ball mouse has two freely rotating rollers. The threads are then stretched and polished by steel rollers and brushes. Crushers usually consist of several stainless steel rollers and gaps. Traction drives transmit power through metal rollers running against mating metal rollers. The cloth is then wound over drying rollers. The rubber rollers on the roadwheels were widened. It consists of a series of short cylindrical rollers held together by side links. These machines generally have two rollers, or drums, covered with card clothing. The belt rode on a series of motorized rollers. The weights kept the twist from backing up before the rollers. Installing smaller diameter rollers results in the reverse effects. However, this resulted in greater stress on the outer rollers. The widths of conjugated rollers and gearwheels in pairs are the same. Touching a plate next to the rollers sends portamento by default.