Monday, October 4, 2010

How A Washing Machine Works

For My First Post I Will Start With The Basics...How A Washer Works.

I hope you find it helpful!  Please let me know what you think.

The operation of front-loading washing machine is fundamentally similar to that of top loaders; however, we will be primarily looking at the top-loading style.

Design variations of washing machines differ by manufacturer, but the general principles are essentially the same, and can be divided into two halves, the washer's control system and the washer's mechanical system. The washer control system consists of a timer (cycle selection mechanism), load size selector (pressure switch), a water temperature selector, lid switch, and start switch. The mechanical system includes the motor, transmission, clutch, inner and outer wash tubs, suspension system, agitator, pump, water valve, and a belt or motor coupling.

Washing machines clean clothing by moving the clothes through the water and detergent mixture. The action of forcing detergent infused water through your clothing fabric is what enables the detergent to chemically loosen dirt embedded in the cloth and separate it from the fabric. Count your blessings; in the old days, people would beat wet clothes against a rock loosen dirt!

 

In top loading washing machines the agitator ratchets back and forth dragging clothing down to the bottom of the washer tub. The clothes then move back to the top where the agitator grabs them again. In a front-loading washing machine, the clothes tumble through the water in the base of the washer tub over and over again. After the water is pumped out, the inner drum uses centrifugal force to squeeze out more water from the clothes by spinning between 500 to 1200 RPM (revolutions per minute.) depending on the washer model.

Tub

All washers have two tubs, the inner tub to contain your clothing, has lots of holes in it allowing water to pass through and the outer tub, which actually contains the water. During the spin portion of the wash cycle the inner tub spins around 500RPM in a top-loading washer and approximately 1000RPM for most front-loading styles. This forces water out of your clothing, using a combination of momentum and inertia through the washer tub and suspensionholes of the inner wash tub to the stationary outer tub.  The drain pump can then remove the wash water.

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Suspension System

Modern washing machines use a suspension system of springs, slide plates, and load bearing pads to keep the wash tub in the correct position, control the forces required for spinning and stopping the inner tub, as well as reduce the amount of noise associated with washer mechanics.

(Watch the tub and suspension repair video)

Timer

A washer’s timer is the brain behind thewasher timer operation.  The timer has many small contact switches that open and close as they are activated by a rotating cam, similar to a music box or player piano. As the switches close different components within the washer are energized so they can perform their task at the proper time.  The timer is usually the first thing blamed for a malfunctioning washer; however, it is rarely the cause.  Timers may fail in the following ways.  The timer motor doesn’t rotate the internal cam, some of the switch contacts weld closed and never open, or some of the switch contacts build up carbon deposits and fail to make contact, not allowing a particular component to receive the electricity needed for operation.

(Watch the control repair video)

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Lid Switch

washer lid switchA lid switch, which indicates whether the lid is open or closed, will interrupt some or allof the washing machine operations.  This is a safety mechanism that has greatly reduced the volume of appliance related injuries.  A washer's timer will generally allow the washer to fill with water while the lid is open; however, most new washers will not allow any mechanical movement while the lid switch is open. Some older models will allow agitation.

(Watch the lid switch repair video)

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Water Valve

washer water valveThe water inlet valve connects to the water supply of your home and allows hot and cold water to flow into the tub by opening an internal gate with an electromagnetic solenoid.

(Watch the water valve repair video)

Pressure switch

washer pressure switchWashing machines commonly use a pressure-sensing switch to control the amount of water released by the water valve into the washtub.  The washer’s pressure-switch is connected to the base of the washer’s outer tub with a clear rubber tube that carries air that increases in pressure as the water level in the washtub increases.  When the air pressure reaches a particular level the switch will “open” stopping the flow of electricity to the water valve allowing it to drop closed.  

(Watch the control repair video)

Agitator

washer agitatorThe agitator is the arm of any washing machine. During the wash cycle, the agitator moves back and forth to pull the clothes through the water enabling the detergent to loosen soil. The washer agitator is directly attached to a drive system that alternates between clockwise and counter clockwise rotation.  Two part agitators have a separate top portion that ratchets with a cam mechanism.  The small cams within the agitator top that control its movement are often called agitator “dogs”.

Some agitators slide onto a plastic hub called an agitator coupling that can strip out and no longer drive the agitator.

(Watch the agitator repair video)

Pump

washer pumpAll washers have a drain pump to force the dirty water up and out of the washer tub. Some washer styles also have a recirculation pump that will recycle the water in the tub back on top of the clothes to encourage clothing movement and reduce the amount of water needed to complete a wash cycle. washer pumps are ether directly attached to the washer’s motor, driven by a belt form the washer motor, or the pump may have its own internal electric motor. All pumps have a relatively small paddle wheel called the impeller that spins, pushing the water in the direction of its rotation.

(Watch the pump repair video)

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Motor

washer motorThe motor drives the agitator, pump, and inner tub. Some washing machines use directdrive, in which the motor is connected directly to the pump and transmission. Other washing machines use a belt drive system in which the motor applys force to the drive system and in some cases the pump with belt and pulley. On some belt driven washing machines, the pump may have its own internal motor powered separately by the timer.

(Watch the motor repair video)

Clutch

washer clutchMost washing machines use a clutch to absorb some of the force generated by fast starting motors. The clutch allows the transmission to grab the tub or agitator in a gradual manner rather than all at once. Some washers use a clutch mechanism while others rely on slippage and gradual tension of the belt and pulley.

(Watch the drive system repair video)

Belt

maytag washer beltA Belt is used to transfer kinetic energy from one mechanical component to another.  A belt can also be used as a clutch to reduce the amount of strain applied by fast starting electric motors used in washers.  A belt’s surface can become “glazed” or burned slightly reducing the belt’ ability to hold a pulley. This lack of holding ability in the belt’s surface leads to slipping creating more heat and burning of the belt’s surface

Motor Coupling

washer motor couplingMany washers use a part called the motor coupling in place of a belt to transfer motion energy from the washer’s motor to the washer’s transmission; this engineering method is called direct drive.

The washer motor coupling is made of rubber and plastic and is fairly common to break when the washer is regularly overloaded, creating a sound something like this

broken washer motor coupling repair help (Click the speaker icon to listen)

Fear not, a washer motor coupling is inexpensive and simple to replace.

(Watch the motor coupling repair video)

 

Transmission

washer transmission

The transmission drives both the spin of the inner tub and the back and forth motion of the agitator. a washer has either a single direction or a reversing motor. With a single direction motor, an electromechanicaldevice (Solenoid) controls whether the transmission drives the agitator or the inner tub. Reversing motors engage the tub when they rotate in one direction and the agitator when they move in the opposite direction.

(Watch the drive system repair video)

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