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Jebel Ali 1 Dubai Washing Machine Repair
Top-loading
The top loading, vertical axis cloth washer, is the dominant design in the United States and Canada. 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.
Top-loading
The top loading, vertical axis cloth washer, is the dominant design in the United States and Canada. 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.
Since the agitator and the drum are separate and distinct in a top-loading washing machine, the mechanism of a top-loader is inherently more complicated than a front-loading machine. Manufacturers have devised several ways to control the motion of the agitator during wash and rinse separately from the high speed rotation of the drum required for the spin cycle. Jebel Ali 1 Dubai Washing Machine Repair
While a top-loading washing machine could use a universal motor or DC brushless motor, it is conventional for top-loading washing machines to use more expensive, heavy, and more electrically efficient and reliable induction motors. The action of a front-loading washing machine is better suited to a motor capable of reversing direction with every reversal of the wash basket; a universal motor is noisier, less efficient, doesn't last as long, but is better suited to the task of reversing direction every few seconds.
An alternative to the oscillating agitator design is the impeller type washtub pioneered by Hoover on its long running Hoovermatic series of top loading machines. Here, an impeller (trademarked by Hoover as a "Pulsator") mounted on the side of the tub spins in a constant direction, and creates a fast moving current of water in the tub which drags the clothes through the water along a toroidal path. The impeller design has the advantage of its mechanical simplicity - a single speed motor with belt drive is all that is required to drive the Pulsator with no need for gearboxes or complex electrical controls, but has the disadvantage of lower load capacity in relation to tub size. Hoovermatic machines were made mostly in twin tub format for the European market - (where they competed with Hotpoint's Supermatic line which used the oscillating agitator design) until the early 1990s. Some industrial garment testing machines still use the Hoover wash action. Al Qusais Second Dubai washing machine repair
The many different ways different manufacturers have solved the same problem over the years is a good example of many different ways to solve the same engineering problem with different goals, different manufacturing capabilities and expertise, and different patent encumbrances.
Reversible motor
In most current 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. Mechanically, this system is very simple.
Mode-changing transmission
In some top loaders, the motor runs only in one direction. During agitation, the transmission converts the rotation into the alternating motion driving the agitator. During the spin cycle, the timer turns on a solenoid which engages a clutch locking the motor's rotation to the wash basket, providing a spin cycle. General Electric's very popular line of Filter-Flo (seen to the right) used a variant of this design where the motor reversed only to pump water out of the machine. The same clutch which allows the heavy tub full of wet clothes to "slip" as it comes up to the motor's speed, is also allowed to "slip" during agitation to engage a Gentle Cycle for delicate clothes.
Whirlpool (Kenmore) created a popular design demonstrating the complex mechanisms which could be used to produce different motions from a single motor with the so-called "wig wag" mechanism, which was used for decades until modern controls rendered it obsolete. In the Whirlpool mechanism, a protruding moving piece oscillates in time with the agitation motion. Two solenoids are mounted to this protruding moving piece, with wires attaching them to the timer. During the cycle, the motor operates continuously, and the solenoids on the "wig wag" engage agitation or spin. Despite the wires controlling the solenoids being subject to abrasion and broken connections due to their constant motion and the solenoids operating in a damp environment where corrosion could damage them, these machines were surprisingly reliable.
Reversible motor with mode-changing transmission
Some top-loaders, especially compact apartment-sized washers, use a hybrid mechanism. The motor reverses direction every few seconds, often with a pause between direction changes, to perform the agitation. Spin cycle is accomplished by engaging a clutch in the transmission. A separate motorized pump is generally used to drain this style of machine. These machines could easily be implemented with universal motors or more modern DC brushless motors, but older ones tend to use a capacitor-start induction motor with a pause between reversals of agitation. Al Barsha First Dubai Washing Machine Repair
Top-load advantages
The top-loader's spin cycle between washing and rinsing allows an extremely simple passive fabric softener dispenser, which operates through centrifugal force and gravity. Fabric softener, vinegar, or any other liquid rinse agent, is placed in a cup at the top of the agitator. It "rides along" during the wash cycle. When the spin cycle is engaged, the fabric softener is pulled up by a tapered cup and centrifugal force, where it collects in the top of the spinning agitator. Once the spin cycle is completed, centrifugal force no longer suspends the fabric softener and it falls through the center of the agitator to join the rinse water coming into the tub. The same objective must be accomplished by a solenoid valve or a pump, and associated timer controls and wiring, on a front loader.
A lint trap can also be built into the center of the agitator,or on the drum's walls,passively collecting lint from water forced through the agitator. Front-loaders tend to require separate pumps and plumbing to provide lint filters which are often mounted behind covers on the bottom of the machine.
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 fabric usually fits into a smaller space than dry fabric, a dense wad of fabric 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, burning drive belts, or tearing fabrics - many Whirlpool/Kenmore machines even have a mechanical "fuse" designed to break before the expensive motor is damaged. 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 top-loading machines use mechanisms very similar to front-loading drum machines, and are described below.
Since the agitator and the drum are separate and distinct in a top-loading washing machine, the mechanism of a top-loader is inherently more complicated than a front-loading machine. Manufacturers have devised several ways to control the motion of the agitator during wash and rinse separately from the high speed rotation of the drum required for the spin cycle. Jebel Ali 1 Dubai Washing Machine Repair
While a top-loading washing machine could use a universal motor or DC brushless motor, it is conventional for top-loading washing machines to use more expensive, heavy, and more electrically efficient and reliable induction motors. The action of a front-loading washing machine is better suited to a motor capable of reversing direction with every reversal of the wash basket; a universal motor is noisier, less efficient, doesn't last as long, but is better suited to the task of reversing direction every few seconds.
An alternative to the oscillating agitator design is the impeller type washtub pioneered by Hoover on its long running Hoovermatic series of top loading machines. Here, an impeller (trademarked by Hoover as a "Pulsator") mounted on the side of the tub spins in a constant direction, and creates a fast moving current of water in the tub which drags the clothes through the water along a toroidal path. The impeller design has the advantage of its mechanical simplicity - a single speed motor with belt drive is all that is required to drive the Pulsator with no need for gearboxes or complex electrical controls, but has the disadvantage of lower load capacity in relation to tub size. Hoovermatic machines were made mostly in twin tub format for the European market - (where they competed with Hotpoint's Supermatic line which used the oscillating agitator design) until the early 1990s. Some industrial garment testing machines still use the Hoover wash action. Al Qusais Second Dubai washing machine repair
The many different ways different manufacturers have solved the same problem over the years is a good example of many different ways to solve the same engineering problem with different goals, different manufacturing capabilities and expertise, and different patent encumbrances.
Reversible motor
In most current 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. Mechanically, this system is very simple.
Mode-changing transmission
In some top loaders, the motor runs only in one direction. During agitation, the transmission converts the rotation into the alternating motion driving the agitator. During the spin cycle, the timer turns on a solenoid which engages a clutch locking the motor's rotation to the wash basket, providing a spin cycle. General Electric's very popular line of Filter-Flo (seen to the right) used a variant of this design where the motor reversed only to pump water out of the machine. The same clutch which allows the heavy tub full of wet clothes to "slip" as it comes up to the motor's speed, is also allowed to "slip" during agitation to engage a Gentle Cycle for delicate clothes.
Whirlpool (Kenmore) created a popular design demonstrating the complex mechanisms which could be used to produce different motions from a single motor with the so-called "wig wag" mechanism, which was used for decades until modern controls rendered it obsolete. In the Whirlpool mechanism, a protruding moving piece oscillates in time with the agitation motion. Two solenoids are mounted to this protruding moving piece, with wires attaching them to the timer. During the cycle, the motor operates continuously, and the solenoids on the "wig wag" engage agitation or spin. Despite the wires controlling the solenoids being subject to abrasion and broken connections due to their constant motion and the solenoids operating in a damp environment where corrosion could damage them, these machines were surprisingly reliable.
Reversible motor with mode-changing transmission
Some top-loaders, especially compact apartment-sized washers, use a hybrid mechanism. The motor reverses direction every few seconds, often with a pause between direction changes, to perform the agitation. Spin cycle is accomplished by engaging a clutch in the transmission. A separate motorized pump is generally used to drain this style of machine. These machines could easily be implemented with universal motors or more modern DC brushless motors, but older ones tend to use a capacitor-start induction motor with a pause between reversals of agitation. Al Barsha First Dubai Washing Machine Repair
Top-load advantages
The top-loader's spin cycle between washing and rinsing allows an extremely simple passive fabric softener dispenser, which operates through centrifugal force and gravity. Fabric softener, vinegar, or any other liquid rinse agent, is placed in a cup at the top of the agitator. It "rides along" during the wash cycle. When the spin cycle is engaged, the fabric softener is pulled up by a tapered cup and centrifugal force, where it collects in the top of the spinning agitator. Once the spin cycle is completed, centrifugal force no longer suspends the fabric softener and it falls through the center of the agitator to join the rinse water coming into the tub. The same objective must be accomplished by a solenoid valve or a pump, and associated timer controls and wiring, on a front loader.
A lint trap can also be built into the center of the agitator,or on the drum's walls,passively collecting lint from water forced through the agitator. Front-loaders tend to require separate pumps and plumbing to provide lint filters which are often mounted behind covers on the bottom of the machine.
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 fabric usually fits into a smaller space than dry fabric, a dense wad of fabric 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, burning drive belts, or tearing fabrics - many Whirlpool/Kenmore machines even have a mechanical "fuse" designed to break before the expensive motor is damaged. 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 top-loading machines use mechanisms very similar to front-loading drum machines, and are described below.
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