Contemporary washing machines are available in two main configurations: “top loading” and “front loading”. The “top loading” design, most popular in the United States, Australia and some parts of Europe, places the clothes in a vertically-mounted cylinder, with a propeller-like agitator in the center of the bottom of the cylinder. “Top loading” machines in Asia use impellers instead of agitators. Impellers are similar to agitators except that they don’t have the center post extending up in the middle of the wash tub basket. Clothes are loaded through the top of the machine, which is covered with a hinged door. The “front loading” design, most popular in Europe and the Middle East, instead mounts the cylinder horizontally. Loading is through a glass door at the front of the machine. The cylinder is also called the drum. Agitation is supplied by the back-and-forth rotation of the cylinder, and by gravity. The clothes are lifted up by paddles in the drum and then dropped. This motion flexes the weave of the fabric and forces water and detergent solution through the clothes load. Although rarer, there is also a variant of the horizontal axis design that is loaded from the top, through a small door in the circumference of the drum. These machines usually have a shorter cylinder and are therefore smaller. Top-loading machines in a LaundromatAll washing machines work by using three sources of energy. They use mechanical energy, thermal energy, and chemical action. Mechanical energy is imparted to the clothes load by the rotation of the agitator in top loaders, or by the tumbling action of the drum in front loaders. Thermal energy is supplied by the temperature of the wash bath. Many front loading machines have electrical heating elements to heat the wash bath to near boiling. Chemical action is supplied by the detergent and other laundry chemicals. Front loaders use special detergents that are designed to release different chemical ingredients at different temperatures. This is so that different type of stains and soils will be cleaned from the clothes as the wash water is heated up by the electrical heater. Front loaders also need to use low sudsing detergents because the tumbling action of the drum folds air into the clothes load that can cause over sudsing. Tests comparing front loading and top loading machines have shown that, in general, front-loaders wash clothes more thoroughly, cause less wear, and use less water and energy than top-loaders. As a result of using less water, they require less detergent to be used, or conversely, they can use the same amount of detergent with less water, which increases detergent concentration and increases the amount of chemical action. They also allow a dryer to be more easily mounted directly above the washer. A 50s modelTop-loaders do have the advantage in that they complete a washing cycle much faster, tend to cost less for the same capacity machine, and allow clothes to be removed at intermediate stages of the cycle (for instance, if some clothes within a wash are not to be spun). They also tend to be easier to load and unload, since reaching into the tub does not require stooping. The top loader’s spin cycle between washing and rinsing allows an extremely simple passive fabric softener dispenser, which must be accomplished by a solenoid-operated valve on a front loader. Another advantage to the top-loading design is the reliance on gravity to contain the water, rather than potentially trouble-prone or short-lived front door seals. In the late 1990s, the British inventor James Dyson launched a type of washing machine with two cylinders rotating in opposite directions; which, it is claimed, reduces the wash time and produces cleaner results.
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article “Modern machines”.