=164. Machine with an Oscillating Washing Device.= This washer contains an oscillating device for rubbing the clothes over the corrugated bottom. The rubbing device is also corrugated and is put on top of the clothes and moved backward and forward, thus rubbing them between two wash-boards (Fig. 90). [Illustration: FIG. 90. Oscillating washing machine.] =165. Oscillating Washers.= Oscillating washers have corrugated bottoms. The clothes are put into the machine with the wash water. The washer rocks, throwing the clothes backward and forward thru the water, loosening and squeezing out the dirt. This washer works easiest when the machine is well filled with water. =166. Locomotive Washer.= The locomotive washer (Fig. 91) slides backward and forward, thus churning the water and clothes. It is operated only by power. A heating unit, usually gas, in the base of the machine keeps the water hot. [Illustration: FIG. 91. Locomotive washing machine.] =167. Centrifugal Washer.= A centrifugal washer (Fig. 91-_a_) contains a perforated basket which whirls in the water contained in the machine. The clothes are placed in the basket, rolled into bundles. The rapid whirling thru the water removes the dirt from the clothes. [Illustration: FIG. 91-_a_. Centrifugal washing machine.] =168. Care of Washers.= The bearings and other motor parts of a washing machine should be kept oiled. Keep belts tight. Run the machine about ten minutes each while the clothes are in the first wash water and the two sudsy waters, and five minutes each for the hot and the cold rinse waters. Blueing had better be done in a tub. Wooden machines must dry out occasionally, or else they get slimy. Do not let them get dry enough to crack. Air the machines after use. Cover them when not in use to keep them clean. When a gasoline engine is used in operating a washing machine, it must be set so that the belt will pull straight on the pulley wheel of the machine. The belt should be tight enough to prevent slipping. Stationary washers are set to avoid such troubles, but those which are moved from place to place must be adjusted by the operator. The pulleys must be adjusted to turn at the number of revolutions per minute directed for the washer used. This usually does not exceed 150 revolutions of the motor wheel per minute. Water motors must receive more than 25 pounds of water pressure to operate a washing machine. CHAPTER XXIV WRINGERS =169. Roller Wringer.= The kind of wringer in most general use is the one made of two rollers rotating in opposite directions, the clothes being drawn in between the two by friction, and the water pressed out. (See Fig. 88.)