Functioning of Washing Machines

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Operational Controls

Cycle switch

The operational controls of this machine were designed before the utilization of microcontrollers in appliances. There are no resistors or capacitors present in the entire machine. Let’s begin by examining the cycle switch, as you’ll be amazed by what’s inside.

The cycle switch is responsible for determining the duration of each part of the cycle.

Inside the cycle switch

The switch contains a small motor equipped with a large gear reduction that causes the control dial to turn very slowly. In the upper part of the switch, there is a set of six contacts. These contacts are activated by the small pieces of metal in the plastic arm on the dial. As the dial turns, the bumps on the dial raise and lower the six metal pieces, which open and close the contacts in the upper part of the switch.

Inside the cycle switch

The bumps’ shape can help you understand why the washer knob spins in only one direction: The front side of the bumps has a slope that gradually raises the metal pieces, but the back side does not, so if you attempt to turn the knob backward, the metal pieces wedge against the bumps.

This bumpy plastic disk functions as the software program that runs your washing machine. The length of the bumps determines the length of each part of the cycle, and the distance between bumps determines how long the machine will pause before proceeding to the next task.

The speed and temperature control switches are much simpler than the cycle control switch.

Speed and temperature control switches

These switches control the motor’s speed and determine which of the hot/cold water supply solenoids will open during the wash and rinse cycles. If hot is selected, only the hot water solenoid valve will open when the machine fills; if warm is selected, both will open; and if cold is selected, only the cold water solenoid valve will open.

Inside the speed/temperature control

The speed/temperature control is relatively simple. Each plastic rocker engages with two sets of contacts, either opening or closing the circuit linked to those contacts. For each switch, there is always one closed and one open set of contacts.

The water level sensor employs a pressure switch to determine the water level in the tub.

Water level control switch

This switch determines how high the tub is filled with water.

Water level control switch plumbing

The large end of the hose is connected to the bottom of the tub, while the small end is connected to the switch. As the water level in the tub rises, water also rises in the hose, but the air in the hose is trapped, so as the water rises, the air is compressed.

The water level control switch consists of a small piston inside its housing. The pressure in the hose helps push the piston up until it pops up and closes an electrical contact. The contact’s set point is adjustable, and the cam mechanism shown in the picture is connected to the adjuster knob on the washer’s control panel. As the cam turns, it presses against the cylinder’s spring, making it difficult for the cylinder to pop up. Thus, the water level needs to rise further before the hose’s pressure is high enough to trigger the switch. If you need more information, you can check the links below. The article also provides some related HowStuffWorks articles and more useful links to explore.


1. What is the main principle behind washing machines?

Washing machines work on the principle of using a combination of water, detergent, and mechanical action to loosen and remove dirt and stains from clothes. The machine fills up with water and then agitates the clothes to create a scrubbing action that helps to lift dirt and stains from the fabric. After the clothes have been scrubbed, the machine drains the dirty water and refills with clean water to rinse the clothes. Finally, the machine spins the clothes to remove excess water and prepare them for drying.

2. How do top-loading washing machines differ from front-loading ones?

Top-loading washing machines have a vertical drum that is loaded through a lid on the top of the machine. These machines typically use more water than front-loading machines and are generally less energy-efficient. Front-loading washing machines, on the other hand, have a horizontal drum that is loaded through a door on the front of the machine. These machines use less water and energy than top-loading machines and are generally considered more effective at cleaning clothes.

3. What is the function of the agitator in a washing machine?

The agitator in a washing machine is a mechanism that creates a back-and-forth motion in the water and clothes to help scrub out dirt and stains. The agitator typically consists of a vertical spindle with fins or blades that extend outwards. As the machine fills with water, the agitator spins and moves the clothes around in the water to help break up dirt and stains. Some modern washing machines use alternative methods of cleaning, such as a drum that rotates the clothes gently instead of using an agitator.

4. Can washing machines damage clothes?

While washing machines are designed to clean clothes without damaging them, some fabrics and materials are more delicate than others and can be damaged by the machine’s agitator or spin cycle. To avoid damage to clothes, it’s important to follow the manufacturer’s instructions for washing and drying each item. In general, it’s best to wash delicate items separately on a gentle cycle, using a mild detergent and cold water. It’s also a good idea to use a mesh laundry bag to protect delicate items from getting tangled or snagged in the machine.

5. How can I maintain my washing machine for optimal performance?

To keep your washing machine running smoothly and effectively, it’s important to perform regular maintenance tasks. This includes cleaning the lint filter and detergent dispenser regularly, as well as running an empty hot water cycle with vinegar or bleach to clean out any buildup in the machine. It’s also a good idea to check the machine’s hoses and connections periodically to ensure that they are in good condition and not leaking. Finally, it’s important to follow the manufacturer’s recommendations for load size and detergent usage, as overloading the machine or using too much detergent can lead to poor performance and even damage to the machine.

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