The top-loading or vertical-axis clothes washer is most popular in AustraliaШаблон:Citation needed, New Zealand, Canada, the United States, and Latin America.Шаблон:Citation needed Simplified, very-low-cost versions are made for markets in Asia, Africa, and other less-developed parts of the world.
This design places the clothes in a vertically mounted perforated basket that is contained within a water-retaining tub, with a finned water-pumping agitator in the center of the bottom of the basket. Clothes are loaded through the top of the machine, which is usually but not always covered with a hinged door.
During the wash cycle, the outer tub is filled with water sufficient to fully immerse and suspend the clothing freely in the basket. The movement of the agitator pushes water outward between the paddles towards the edge of the tub. The water then moves outward, up the sides of the basket, towards the center, and then down towards the agitator to repeat the process, in a circulation pattern similar to the shape of a torus. The agitator direction is periodically reversed, because continuous motion in one direction would just lead to the water spinning around the basket with the agitator rather than the water being pumped in the torus-shaped motion. Some washers supplement the water-pumping action of the agitator with a large rotating screw on the shaft above the agitator, to help move water downwards in the center of the basket.
In most top-loading washers, if the motor spins in one direction, the gearbox drives the agitator; if the motor spins the other way, the gearbox locks the agitator and spins the basket and agitator together. Similarly if the pump motor rotates one way it recirculates the sudsy water; in the other direction it pumps water from the machine during the spin cycle. Because they usually incorporate a gearbox, clutch, crank, etc., top-loading washers are mechanically more complex than front loading machines. An example of the complex mechanisms once used to produce different motions from a single motor is the so-called "wig wag" mechanism, which was used for decades until modern controls rendered it obsolete. The electromechanical components in conventional top-load washers have largely reached maturity, and there is a trend towards simpler mechanical components but greater complexity in electronic controllers.
The top-loader's spin cycle between washing and rinsing allows an extremely simple fabric softener dispenser, which operates passively through centrifugal force and gravity. The same objective must be accomplished by a solenoid 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. Top loaders may require less periodic maintenance since there is no need to clean a door seal or bellows, although a plastic tub may still require a periodic "maintenance wash" cycle (described below).
As with front-loading washers, clothing should not be packed tightly into a top-loading washer. Although wet cloth usually fits into a smaller space than dry cloth, a dense wad of cloth can restrict water circulation, resulting in poor soap distribution and incomplete rinsing. Extremely overloaded top-loading washers can either jam the motion of the agitator, overloading or damaging the motor or gearbox, or tearing fabrics. Extreme overloading can also push fabrics into the small gap between the underside of the agitator and the bottom of the wash basket, resulting in fabrics wrapped around the agitator shaft, possibly requiring agitator removal to unjam.
Some machines which actually load from the top are otherwise much more similar to front-loading drum machines, and are described below.
The front-loading or horizontal-axis clothes washer is the dominant design in Europe, the Middle East, Asia, Africa, and much of the rest of the world. In the US and elsewhere, most "high-end" washing machines are of this type. In addition, most commercial and industrial clothes washers around the world are of the horizontal-axis design.
This layout mounts the inner basket and outer tub horizontally, and loading is through a door at the front of the machine. The door often but not always contains a transparent window. Agitation is supplied by the back-and-forth rotation of the cylinder and by gravity. The clothes are lifted up by paddles on the inside wall of the drum and then dropped. This motion flexes the weave of the fabric and forces water and detergent solution through the clothes load. Because the wash action does not require the clothing be freely suspended in water, only enough water is needed to moisten the fabric. Because less water is required, front-loaders typically use less soap, and the repeated dropping and folding action of the tumbling can easily produce large amounts of foam or suds.
Front-loaders control water usage through the surface tension of water, and the capillary wicking action this creates in the fabric weave. A front-loader washer always fills to the same low water level, but a large pile of dry clothing standing in water will soak up the moisture, causing the water level to drop. The washer then refills to maintain the original water level. Because it takes time for this water absorption to occur with a motionless pile of fabric, nearly all front-loaders begin the washing process by slowly tumbling the clothing under the stream of water entering and filling the drum, to rapidly saturate the clothes with water.
Front-loading washers are mechanically simple compared to top-loaders, with the main motor (usually a universal motor) normally being connected to the drum via a grooved pulley belt and large pulley wheel, without the need for a gearbox, clutch or crank. But front-load washers suffer from their own technical problems, due to the drum lying sideways. For example, a top loading washer keeps water inside the tub merely through the force of gravity pulling down on the water, while a front-loader must tightly seal the door shut with a gasket to prevent water dripping onto the floor during the wash cycle. This access door is locked shut during the entire wash cycle, since opening the door with the machine in use could result in water gushing out onto the floor. For front-loaders without viewing windows on the door, it is possible to accidentally pinch fabric between the door and the drum, resulting in tearing and damage to the pinched clothing during tumbling and spinning.
Nearly all front-loader washers for the consumer market must also use a folded flexible bellows assembly around the door opening, to keep clothing contained inside the basket during the tumbling wash cycle.Шаблон:Citation needed If this bellows assembly were not used, small articles of clothing such as socks could slip out of the wash basket near the door, and fall down the narrow slot between the outer tub and basket, plugging the drain and possibly jamming rotation of the inner basket. Retrieving lost items from between the outer tub and inner basket can require complete disassembly of the front of the washer and pulling out the entire inner wash basket. Commercial and industrial front-loaders used by businesses (described below) usually do not use the bellows, and instead require all small objects to be placed in a mesh bag to prevent loss near the basket opening.
The bellows assembly around the door is a potential source of problems for the consumer front-loader. The bellows has a large number of flexible folds to permit the tub to move separately from the door during the high speed extraction cycle. On many machines, these folds can collect lint, dirt, and moisture, resulting in mold and mildew growth, and a foul odor. Some front-loading washer operating instructions say the bellows should be wiped down monthly with a strong bleach solution, while others offer a special "freshening" cycle where the machine is run empty with a strong dosing of bleach. In the past, suggested remedies have included adding vinegar to the laundry detergent, running an empty cycle with bleach every few weeks, wiping the door gasket with a diluted bleach solution every other week, and leaving the front-loading washer door ajar between loads.
Compared to top-loading washers, clothing can be packed more tightly in a front loader, up to the full drum volume if using a cottons wash cycle. This is because wet cloth usually fits into a smaller space than dry cloth, and front loaders are able to self-regulate the water needed to achieve correct washing and rinsing. Extreme overloading of front-loading washers pushes fabrics towards the small gap between the loading door and the front of the wash basket, potentially resulting in fabrics lost between the basket and outer tub, and in severe cases, tearing of clothing and jamming the motion of the basket.
[править] Variant and hybrid designs
There are many variations of these two general themes. Top-loading machines in Asia use impellers instead of agitators. Impellers are similar to agitators except that they do not have the center post extending up in the middle of the wash tub basket.
Some machines which actually load from the top are otherwise much more similar to front-loading drum machines. They have a drum rotating around a horizontal axis, as a front-loader, but there is no front door; instead there is a liftable lid which provides access to the drum, which has a hatch which can be latched shut. Clothes are loaded, the hatch and lid are closed, and the machine operates and spins just like a front-loader. These machines are narrower but usually taller than front-loaders, usually have a lower capacity, and are intended for use where only a narrow space is available, as is sometimes the case in Europe. They have incidental advantages: they can be loaded without bending down; they do not require a perishable rubber bellows seal; and instead of the drum having a single bearing on one side, it has a pair of symmetrical bearings, one on each side, avoiding asymmetrical bearing loading and potentially increasing life.
There are also combo washer dryer machines that combine washing cycles and a full drying cycle in the same drum, eliminating the need to transfer wet clothes from a washer to a dryer machine. In principle, these machines are convenient for overnight cleaning (the combined cycle is considerably longer), but the effective capacity for cleaning larger batches of laundry is drastically reduced. The drying process tends to use much more energy than using two separate devices, because a combo washer dryer not only must dry the clothing, but also needs to dry out the wash chamber itself. These machines are used more in Europe and the UK, because they can be fitted into small spaces, and many can be operated without dedicated utility connections.
True front-loaders, and top-loading machines with horizontal-axis drum as described above, can be compared with top-loaders on a number of aspects:
- Efficient cleaning: Front-loaders usually use less energy, water, and detergent compared to the best top-loaders.<ref>Шаблон:Cite web</ref> "High Efficiency" washers use 20% to 60% of the detergent, water and energy of "standard" washers. They usually take somewhat longer (20–110 minutes) to wash a load, but are often computer controlled with additional sensors, to adapt the wash cycle to the needs of each load. As this technology improves, the human interface will also improve, to make it easier to understand and control the many different cleaning options.Шаблон:Citation needed
- Water usage: Front-loaders usually use less water than top-loading residential clothes washers. Estimates are that front-loaders use from one third<ref>Шаблон:Cite web</ref> to one half<ref>Шаблон:Cite web</ref> as much water as top-loaders.
- Spin-dry effectiveness: Front-loaders (and European horizontal axis top loaders) offer much higher maximum spin speeds of up to 2000 RPM, although home machines tend to be in the 1000 to 1400 RPM range, while top-loaders (with agitators) do not exceed 1140 RPM. High-efficiency top-loaders with a wash plate (instead of an agitator) can spin up to 1100 RPM, as their center of gravity is lower. Higher spin speeds remove much more residual water, making clothes dry faster. This also reduces time and energy if clothes are dried in a clothes dryer.Шаблон:Citation needed
- Cycle length: Top-loaders have tended to have shorter cycle times, in part because their design has traditionally emphasized simplicity and speed of operation more than resource conservation.
- Wear and abrasion: Top-loaders require an agitator or impeller mechanism to force enough water through clothes to clean them effectively, which greatly increases mechanical wear and tear on fabrics. Front-loaders use paddles in the drum to repeatedly pick up and drop clothes into water for cleaning; this gentler action causes less wear. The amount of clothes wear can be roughly gauged by the amount of accumulation in a clothes dryer lint filter, since the lint largely consists of stray fibers detached from textiles during washing and drying.
- Difficult items: Top-loaders may have trouble cleaning large items, such as sleeping bags or pillows, which tend to float on top of the wash water rather than circulate within it. In addition, vigorous top-loader agitator motions may damage delicate fabrics.
- Noise: Front-loaders tend to operate more quietly than top-loaders because the door seal helps contain noise, and because there is less of a tendency to imbalance. Top-loaders usually need a mechanical transmission, which can generate more noise than the rubber belt or direct drive found in most front loaders.
- Compactness: True front-loading machines may be installed underneath counter-height work surfaces. A front-loading washing machine, in a fully fitted kitchen, may even be disguised as a kitchen cabinet. These models can also be convenient in homes with limited floor area, since the clothes dryer may be installed directly above the washer ("stacked" configuration).
- Water leakage: Top-loading machines are less prone to leakage, because simple gravity can reliably keep water from spilling out the loading door on top. True front-loading machines require a flexible seal or gasket on the front door, and the front door must be locked during operation to prevent opening, lest large amounts of water spill out. This seal may leak and require replacement. However, many current front-loaders use so little water that they can be stopped mid-cycle for addition or removal of laundry, while keeping the water level in the horizontal tub below the door level. Best practice installations of either type of machine will include a floor drain or an overflow catch tray with a drain connection, since neither design is immune to leakage or a solenoid valve getting stuck in the open position.
- Maintenance and reliability: Top-loading washers are more tolerant of maintenance neglect, and may not need a regular "freshening" cycle to clean door seals and bellows. During the spin cycle, a top-loading tub is free to move about inside the cabinet of the machine, using only a lip around the top of the inner basket and outer tub to keep the spinning water and clothing from spraying out over the edge. Therefore, the potentially problematic door-sealing and door-locking mechanisms used by true front-loaders are not needed. On the other hand, top-loaders use mechanical gearboxes that are more vulnerable to wear than simpler front-load motor drives.
- Accessibility and ergonomics: Front-loaders are more convenient for very short people and those with paraplegia, as the controls are front-mounted and the horizontal drum eliminates the need for standing or climbing. For people who are not unusually short, top-loaders may be easier to load and unload, since reaching into the tub does not require stooping. Risers, also referred to as pedestals, often with storage drawers underneath, can be used to raise the door of a true front-loader closer to the user's level.
- Initial cost: In countries where top-loaders are popular, front-loaders tend to be more expensive to buy than top-loaders, though their lower operating costs can ultimately lead to lower total cost of ownership, especially if energy, detergent, or water are expensive. On the other hand, in countries with a large front-loader user base, top-loaders are usually seen as alternatives and more expensive than basic off-brand front loaders, although without many differences in total cost of ownership apart from design-originated ones. In addition, manufacturers have tended to include more advanced features such as internal water heating, automatic dirt sensors, and high-speed emptying on front-loaders, although some of these features could be implemented on top-loaders.
[править] Wash cycles
The earliest washing machines simply carried out a washing action when loaded with clothes and soap, filled with hot water, and started. Over time machines became more and more automated, first with very complex electromechanical controllers, then fully electronic controllers; users put clothes into the machine, select a suitable program via a switch, start the machine, and come back to remove clean and slightly damp clothes at the end of the cycle. The controller starts and stops many different processes including pumps and valves to fill and empty the drum with water, heating, and rotating at different speeds, with different combinations of settings for different fabrics.
Many front loading machines have internal electrical heating elements to heat the wash water, to near boiling if desired. Chemical cleaning action of the detergent and other laundry chemicals increases greatly with temperature. Washing machine with internal heaters can use special detergents formulated to release different chemical ingredients at different temperatures, allowing different type of stains and soils to be cleaned from the clothes as the wash water is heated up by the electrical heater. Higher-temperature washing uses more energy, and many fabrics are damaged at higher temperatures. Temperatures exceeding 40 °C have the undesirable effect of inactivating the enzymes when using biological detergent.
Many machines are cold-fill, connected to cold water only, which they heat to operating temperature. Where water can be heated more cheaply or with less carbon dioxide emission than by electricity, cold-fill operation is inefficient.
Front loaders need to use low-sudsing detergents because the tumbling action of the drum folds air into the clothes load that can cause over-sudsing and overflows. However, due to efficient use of water and detergent, the sudsing issue with front-loaders can be controlled by simply using less detergent, without lessening cleaning action.
Washing machines perform several rinses after the main wash to remove most of the detergent. Modern washing machines use less water due to environmental concerns; however, this has led to the problem of poor rinsing on many washing machines on the market,<ref name="whitegoodshelp1">Шаблон:Cite web</ref> which can be a problem to people who are sensitive to detergents. The Allergy UK website suggests re-running the rinse cycle, or rerunning the entire wash cycle without detergent.<ref>Шаблон:Cite web</ref> In response to complaints, many washing machines allow the user to select additional rinse cycles, at the expense of higher water usage and longer cycle time.
Higher spin speeds remove more water, leading to faster drying. If a heated clothes-drier is used after the wash and spin, energy use is reduced if more water has been removed from clothes. However, faster spinning can crease clothes more. Also, mechanical wear on bearings increases rapidly with rotational speed, reducing life. Early machines would spin at only 300 RPM and, because of lack of any mechanical suspension, would often shake and vibrate.
Early front-loading machines, especially those manufactured in warm Mediterranean countries such as Italy, had low maximum spin speeds such as 800 RPM or less. Nowadays, a spin speed of 1200 RPM is common, and a peak spin speed as high as 1600 RPM is available on many machines. Some current models in Europe have speeds of 1800 RPM, while a few high-end washing machines have a spin speed of 2000 RPM.
Many modern machines are equipped with an automatic clothes load balancer, using a sealed ring of viscous liquid, that helps to counteract any out-of-balance distribution. Better machines may include internal suspension and shock systems to reduce noise, and sensors and software to detect and correct an out-of-balance load.
Front-loading washers can be significantly quieter during spin than top-loaders because of the lack of a noisy gearbox to drive the machine's moving parts. However, because they were not as susceptible to gravitational forces and imbalances, some early top-loading machines had spin speeds in excess of 1000 RPM, although some were as low as 360 RPM. Most US top-loading washers have spin speeds less than 1000 RPM.
Separate spin-driers, without washing functionality, are available for specialized applications. For example, a small high-speed centrifuge machine may be provided in locker rooms of communal swimming pools to allow wet bathing costumes to be substantially dried to a slightly damp condition after daily use.
[править] Maintenance wash
Many home washing machines use a plastic, rather than metal, outer shell <ref>Шаблон:Cite web</ref> to contain the wash water; residue can build up on the plastic tub over time. Some manufacturers advise users to perform a regular maintenance or "freshening" wash to clean the inside of the washing machine of any mold, bacteria, encrusted detergent, and unspecified dirt more effectively than with a normal wash.
A maintenance wash is performed without any laundry, on the hottest wash program,<ref>Шаблон:Cite web</ref> adding substances such as white vinegar, 100 grams of citric acid, a detergent with bleaching properties, or a proprietary washing machine cleaner. The first injection of water goes into the sump<ref>Шаблон:Cite web</ref> so the machine can be allowed to fill for about 30 seconds before adding cleaning substances.
[править] Efficiency and standards
Capacity and cost are both considerations when purchasing a washing machine. All else being equal, a machine of higher capacity will cost more to buy, but will be more convenient if large amounts of laundry must be cleaned. Fewer runs of a machine of larger capacity may have lower running costs and better energy and water efficiency than frequent use of a smaller machine, particularly for large families. Running a large machine with small loads is wasteful.
For many years energy and water efficiency were not regulated, and little attention was paid to them. From the last part of the twentieth century increasing attention was paid to efficiency, with regulations enforcing some standards, and efficiency being a selling point, both to save on running costs and to reduce carbon dioxide emissions associated with energy generation, and waste of water.
As energy and water efficiency were regulated, and a selling point, but effectiveness of rinsing was not, manufacturers tended to reduce the degree of rinsing after washing, saving water and motor energy. This had the side-effect of leaving more detergent residue in clothes. Insufficient rinsing can leave enough detergent in clothes to affect people with allergies or sensitivity.<ref name="whitegoodshelp1"/>
Washing machines display an EU Energy Label with grades for energy efficiency, washing performance and spin efficiency. Grades run from A+++ to G (best to worst), providing a simple method for judging running costs and performance. For example a "Triple A" (AAA)-rated machine indicates lowest energy consumption, best wash and best water extraction (i.e. spin) performance. This has had the desired effect of driving customers toward more efficient washing machines and away from less efficient ones.
[править] United States
Top-loading and front-loading clothes washers are covered by a single Federal Standard regulating energy consumption. The Federal Standard applicable until January 1, 2011 included no restriction on water consumption; washer manufacturers faced no legal restriction on how much unheated rinse water could be used.<ref>Шаблон:Cite web</ref> Energy consumption for clothes washers is quantified using the energy factor.
After mandatory Federal Standards were introduced, many US clothes washers were manufactured to be more energy- and water-efficient than required by the federal standard, or even the more stringent Energy Star standard.<ref>Шаблон:Cite web</ref> Manufacturers may be motivated to exceed mandatory standards by a program of direct-to-manufacturer tax credits.<ref>Шаблон:Cite web</ref> However, excessive energy conservation may lead to less satisfactory cleaning.<ref>Шаблон:Cite web</ref>
[править] Commercial use
A commercial washing machine is intended for more frequent use than a consumer washing machine. Durability and functionality is more important than style; most commercial washers are bulky and heavy, and have a sharp-edged square appearance, often with more expensive stainless steel construction to minimize corrosion in a constantly moist environment. They are built with large easy-to-open service covers, and washers are designed not to require access to the underside for service. Often commercial washers are installed in long rows with a wide access passageway behind all the machines to allow maintenance without moving the heavy machines.
[править] Laundromat machines
Many commercial washers are built for use by the general public, and are installed in publicly accessible laundromats or laundrettes, operated by money accepting devices or card readers. The features of a commercial laundromat washer are more limited than a consumer washer, usually offering just two or three basic wash programs and an option to choose wash cycle temperatures.
The common front-loading commercial washing machine also differs from consumer models in its expulsion of wash and rinse water. While the consumer models pump used washer water out, allowing the waste line to be located above the washer, front loading commercial machines generally use only gravity to expel used water. A drain in the rear, at the bottom of the machine opens at the appointed time during the cycle and water flows out. This creates the need for a drainage trough behind machines, which leads to a filter and drain. The trough is usually part of a cement platform built for the purpose of raising the machines to a convenient height, and can be seen behind washers at most laundromats.
Most laundromat machines are horizontal-axis front-loading models, because of their lower operating costs (notably lower consumption of expensive hot water).
[править] Industrial washers
By contrast, commercial washers for internal business operations (still often referred to as "washer/extractor" machines) may include features absent from domestic machines. Many commercial washers offer an option for automatic injection of five or more different chemical types, so that the operator does not have to deal with constantly measuring out soap products and fabric softeners for each load by hand. Instead, a precise metering system draws the detergents and wash additives directly from large liquid-chemical storage barrels and injects them as needed into the various wash and rinse cycles. Some computer-controlled commercial washers offer the operator complete control over the various wash and rinse cycles, allowing the operator to program custom washing cycles.
Most large-scale industrial washers are horizontal-axis machines, but may have front-, side-, or top-load doors. Some industrial clothes washers can batch-process up to 800 pounds (360 kg) of textiles at once, and can be used for extremely machine-abusive washing tasks such as stone washing or fabric bleaching and dyeing.
An industrial washer can be mounted on heavy-duty shock absorbers and attached to a concrete floor, so that it can extract water from even the most severely out-of-balance and heavy wash loads. Noise and vibration is not as unacceptable as in a domestic machine. It may be mounted on hydraulic cylinders, permitting the entire washer to be lifted and tilted so that fabrics can be automatically dumped from the wash drum onto a conveyor belt once the cycle is complete.
One special type of continuous-processing washer is known as the tunnel washer. This specialized high-capacity machine does not have a drum where everything being washed undergoes distinct wash and rinse cycles, but moves the laundry slowly and continuously through a long, large-diameter horizontal-axis rotating tube in the manner of an assembly line, with different processes at different positions.
[править] Social impact
The historically laborious process of washing clothes (a task which often had a whole day set aside to perform) has at times been labelled "woman's work".
In 2009 L'Osservatore Romano published an article entitled "The Washing Machine and the Liberation of Women" that was controversially meant to demonstrate that the washing machine had done more for the liberation of women than the contraceptive pill and abortion rights, which are often associated with Women's Day.<ref>Шаблон:Cite web</ref> The article shocked Italian feminists and provoked criticism from Opposition MP Paola Concia.<ref>Шаблон:Cite web</ref> A study from Université de Montréal, Canada presented a similar point of view.<ref>Шаблон:Cite web</ref>
Swedish statistician Hans Rosling suggested that the positive effect the washing machine had on the liberation of women, makes it "the greatest invention of the industrial revolution".<ref>Шаблон:Cite web</ref> For instance, historian Frances Finnegan credits the rise of this technology in helping undercut the economic viability of the Magdalene Asylums in Ireland, later revealed to be inhumanly abusive prisons for women with often little opportunity for release, by supplanting their laundry businesses and prompting the eventual closure of the institutions as a whole.<ref>Шаблон:Cite book</ref>
[править] Environmental impact
Due to the increasing cost of repairs relative to the price of a washing machine, there has been a major decline in the number of washing machines being repaired, rather than discarded, when faulty, to the detriment of the environment. The cost of repair and the expected life of the machine once repaired often make the purchase of a new machine seem like the better option.<ref>Шаблон:Cite web</ref>
Different washing machine models vary widely in their use of water, detergent, and energy. The energy required for heating is large compared to that used by lighting, electric motors and electronic devices. Because of their use of hot water, washing machines are among the largest consumers of energy in a typical modern homeШаблон:Citation needed.