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Components of Washing Machine

Page of Contents:                                                                                      Page

               I.      Title Page                                                                                          1

             II.      Page of Contents                                                                              1

            III.      Introduction                                                                                        1

A.     The Components and their Descriptions                                             2

1.      The Motor                                                                               2

2.      The Fill Valve                                                                         3

3.      The Tubs                                                                                3

4.      Clutch and Brake Mechanism                                                         4

5.      Motor Coupler and Belt                                                        4

6.      Central Agitator                                                                     5

7.      The Gearbox                                                                          5

B.   Major Systems                                                                           7

1.      Cable and Pulley Support System                                     8

2.      Vibration-Damping System                                                8

C.      Controls                                                                                      9

1.      Cycle Switches                                                                                 9

2.      Speed and Temperature Control Switches                                  10

3.      Water Level Control Switch                                                            10

4.      Timer Selector Switches                                                     12

         IV.       Summary and Conclusion                                                                           12



            This paper enumerates and discusses the compartments that made up the washing machine.  Additionally, the systems involve in the function of the machine has been also identified and described.  Generally, the content of this paper can be broken down into two parts: one is the identification and enumeration of the major parts of the washing machine and the other one is the description of the different essential systems involve in the washing machine.  At the end of the descriptions and enumeration is the summary and conclusion that this paper has come up with. 

The Components and their Descriptions:

            Inside the washing machine is a pack of components and parts that makes up the machine.  Additionally, the components are also the ones responsible why most washing machines are quite heavy. 

  1. The Motor

The Motor, along with the counterweight can be accounted to the explanation of why washing machines are usually heavy and it also plays an important role in the function of the washing machine.  Moreover, the motor drives the agitator during the wash cycle and spins the clothes during the damp dry or spin cycle.  It is then the role of the pump in removing the water from the tub and lifting it out to the drain. 

The motor inside the washing machine works in two ways.  In one direction, the motor works through a clutch and a transmission to spin the inner tub and through centrifugal force, this motion causes the water to be forced out of the clothes into the outer tub where it is pumped out of the machine.  On the opposite direction, the motor works through the same clutch and transmission in order to move the agitator back and forth during the wash cycle. 

However, on other machines, the motor runs in only one direction. In these machines an electro-mechanical device automatically shifts the transmission from its agitate settings to its spin settings (

Motor and the Counterweight

            The counterweight literally functions to balance the equally heavy electric motor.  This electric motor drives the very heavy gearbox that is attached to the steel inner tub.

  1. The Fill Valve

             This compartment of the washing machine is sometimes called as the water inlet valve.  This is just about the size of a coffee cup which controls the entry of hot and cold water into the machine.  The fill valve can be broken down into three major components: (1) a hot-water solenoid, (2) a cold-water solenoid, and (3) a mixing valve body.  Correspondingly, the inlet valve utilizes three hoses for its three major components respectively. 

            When electricity flows to one or both solenoids, water flows through the valve into the washing machine's inner tub. When the electricity stops, the water also stops (


  1. The Tubs

            The washing machine has two steel tubs inside the machine – the inner tub and the outer tub.  The inner tub is the one that holds the clothes.  In most of the contemporary washing machines, the inner tub has several small holes that allow the passage and flow of water through an outer tub.  It has an agitator in the middle of it, and the sides are perforated with holes so that when the tub spins, the water can leave.  The inner tub is attached to the gearbox, which is also attached to the black metal frame that holds the motor and the concrete weight. 

The Outer Tub

The outer tub, on the other hand, is a solid compartment that holds seals in all the water and is bolted to the body of the washer.  For the reason that the inner tub vibrates and shakes during the wash cycle, it has to be accumulated in a way that lets it move around without banging into other parts of the machine.

  1. Clutch and Brake Mechanism

Motors can start up and reach full speed in a second or less, which is too fast for many of the components the motor drives.  For this reason, most washing machines use an automatic clutch to dampen the effect of the motor starting up.

            On some washing machines, the clutch is just a combination of the drive belt slipping temporarily on a pulley and gradually tightening. On other units, the clutch is more like one you would find in a car--it uses a drum-and-pad combination of components.

When the lid is raised on a top-loading washing machine, some functions cease. On all machines the spin cycle stops, which brings the drum to a rapid halt. Many units use a special braking mechanism to stop the spinning inner tub. It is similar in design to the brakes on a car.

  1. Motor Coupler and Belt

A few types of washing machines use a coupler to connect the motor directly to the transmission.  It makes the connection without the need for a belt. The coupler is a rubber disc ½ inch thick by 1-½ inches in diameter, sandwiched between two plastic sprockets.  Many other washing machines use belts to connect the motor to the transmission or pump. A belt is a black, rubber, continuous rope-like component--usually a loop of about 24 to 30 inches.

The belt provides a desirable "weak link" in a washing machine. That is, if the tub or agitator were to become stuck or jammed, the belt is more likely to fail, which would preserve the transmission and other critical components

  1. The Central Agitator

            This part of the washing machine spins around clockwise and counterclockwise at about three-fourths of a revolution dipping the clothes through the water to wash them.  The clothes keep moving from the top of the tub down to the bottom and back again.  This motion allows the detergent and water to reach every part of the clothing and loosens the soil (

  1. The Gearbox

The gearbox is one of the coolest parts of the washing machine.  If you spin the pulley on the gearbox one way, the inner shaft turns slowly back and forth, reversing direction about every half-revolution.  If you spin the pulley the other way, the flange spins at high speed, spinning the whole tub with it.

Gearbox Agitation Mechanism

Here we can see a gear with a link attached to it. This link is just like the one attached to an old steam train wheel -- as the gear (along with the link) turns, it pushes another pie-shaped piece of gear back and forth.  This pie-shaped gear engages a small gear on the inner shaft, which leads to the spline.  In addition to rotating the inner shaft in alternating directions, there are other gears within the system that provide a gear reduction to slow the rotation.  Because the motor spins only at one speed, spin-cycle speed, a gear reduction is necessary to facilitate the slower wash cycle.

Gear Reduction

When the washer goes into spin cycle, the whole mechanism locks up, causing everything to spin at the same speed as the input, which is hooked up to the motor. The interesting thing here is that when the motor spins the gearbox in one direction, the agitator runs, and when it spins it the other way, the whole machine locks up. How does it do this?

In the figure above, notice the gear with the angled teeth.  There is also a smaller gear with angled teeth behind the big one in the foreground.  These are the only two gears with angled teeth.  Depending on which way the gears are spinning, the angle on the teeth will tend to force the inner gear to slide either to the left or to the right inside the gearbox. If it slides to the left, it engages a mechanism that locks up the gearbox (


B.   Major Systems

  1. Cable-and-pulley support system

The picture above shows just the black metal frame, without the tub or gearbox. The cable that you see on the left side of the picture is the other end of the same cable that you see on the right side.  There are a total of three pulleys, so that if one side of the frame moves up, the other side moves down.  This system supports the weight of the heavy components, letting them move in such a way as not to shake the entire machine (

  1. Vibration-Damping System

            This system is also referred to as vibration-damping system that prevents the heavy compartments from swinging around through the use of friction in absorbing some of the force from the vibrations. 

In each of the four corners of the machine is a mechanism that works a little like a disc brake. The part attached to the washer frame is a spring. It squeezes two pads against the metal plate that is attached to the black frame. You can see where the pads have polished the plate from movement during vibration (

C.     Controls

    1. Cycle Switch

Cycle Switch

            The cycle switch functions in determining how long the different parts of the cycle last.  Inside the switch is a little motor equipped with a very large gear reduction that makes the control dial turn very slowly. In the top half of the switch, there is a set of six contacts.  These are actuated by the small pieces of metal in the plastic arm on the dial. As the dial spins, bumps on the dial raise and lower the six metal pieces, which close and open the contacts in the top half of the switch.

Inside the Cycle Switch

    1. Speed and Temperature Control Switches

            These switches are much simpler than that of the cycle control switch.  These switches control the speed of the motor and determine which of the hot/cold water supply solenoids will open during the wash and the 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.

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

Speed and Temperature Control Switches

    1. Water Level Control Switch

            The level sensor uses a pressure switch to detect the water level in the tub.  This water level control switch controls how high the tub fills with water.

Water level control switch

Water level control switch plumbing

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

Inside the housing of this switch is a little piston.  The pressure in the hose pushes the piston up.  When it is raised far enough, it pops up and closes an electrical contact. This set point, where the contact is lost, is adjustable, and in the picture you can see the cam mechanism that is connected to the adjuster knob on the control panel of the washer. As the cam turns, it presses a spring against the cylinder, making it harder for the cylinder to pop up. This means that the water level will have to rise some more before the pressure in the hose will be high enough to trigger the switch (


    1. Timer and selector switches

The timer switch is usually the largest dial on the main control panel.  It can be either a mechanical device much like a simple clock, or completely electronic with just a digital readout.  The timer runs the washing machine in a pre-determined pattern. It provides the electricity to all of the washing machine components at the correct time and for the correct length of time.

The Start switch is usually part of the timer knob.  When you set the timer to the proper cycle, you either pull or push the timer knob to start the cycle.  The selector switches or knobs vary from machine to machine.  Most washing machines have one or several switches or knobs on the control panel besides the Timer/Start switch.  These let you adjust certain settings; for example, the water temperature, spins speed, timer cycle, and so on.  Normally, the washing machine completes the cycle selected on the timer, regardless of how you set these switches and knobs.


IV. Summary and Conclusion:

            In summing it up, there are seven major components stated and described according to their specific functions.  Each of them coordinates with other parts in the proper functioning of the washing machine.  Additionally, the two systems that have been developed are for the support and safety of the machine as it operates. 

Washing machine as the given appliance of study is such an ideal one for engineering learning.  The major components of the machine give the basics of how things work inside a washing machine.  Not many of the people using the machine have an idea of how it works but at least with this paper users are provided with knowledge about the specifics of the machine they are using.  The most important matter to be recognized in knowing about this particular machine is its safety features that go along with its ease of use. 





Nice, K n.d. How Washing Machines Work,, viewed 20 April 2006 from How Washing Machines Work. Viewed 20 April 2006 from


Anonymous said…
Anonymous said…
soulsearcher said…
i would have been better if i have found this blog on research proposals while i was working mine last year...but anyway, that's the past..all i wish for now is to win in uk lottery
Anonymous said…
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A friend to everybody is a friend to nobody...................................................
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