Electrolux's Automatic Vacuum Cleaners
A quick bit of info on your vacuum, how it works, and how to keep it working

Vacuum cleaners are all about suction- or are they? Actually, suction doesn't actually exist. No really! It isn't a "real" force. Let me explain.

In a vacuum cleaner, you have a motor attached to a fan that moves air through the machine: This is known as Air Flow. How much air moves through the machine depends on several factors- the size of the fan, the number and shape of the fan's blades and speed that the fan is turning are the factors most often considered. Obviously, another factor to consider is what may impede air flow- dirt, for the most part.

But there's another, very important and obvious factor that is almost always overlooked. See if you can figure out what it is. Remember, there's no suction, just air flow. Which is how much air moves through the vacuum cleaner. See it? How much air flows through the machine... How... much... air... Ah-ha! Without air, there is no airflow, and thus no apparent suction. A vacuum cleaner in space won't do much, as there is nothing for it to move (except a few random atoms, perhaps).

No pressure! Well, actually you want pressure, or your vacuum cleaner won't suck.


Well, there's air everywhere on earth, at least above ground, right? Well, yes... But the amount of air isn't the same everywhere. The earth's atmosphere is nearly the same height all over the globe, if you measured out from the center of the earth. The atmosphere does bulge out at the equator a little bit more than at the poles, but since few people actually live at the poles, there is little need to consider this as a factor. So, while the height of the atmosphere is nearly the same, the land below is not.

Your altitude affects air pressure. Other factors that also affect the weight of the atmosphere above you include Air Temperature and Moisture Content (as well as pollutants). Now, colder air is 'heavier' and warmer air is 'lighter' - but to balance things out, nature has a little trick: Moist air is heavier, and cold air can't hold as much moister as warm air, so the differences of air pressures in different climates has little effect on your vacuum cleaner- or at least what you will notice. Here are a couple of links to learn more about air pressure and factors that affect it: NOVA Online and NASA Kids-It's a Breeze.

Instead we should consider only the altitude of the land you are on. Land at sea level has more air above it than, say, at the top of Mount Everest. Everything in the universe has weight, and air is no exception. At sea level, the air's weight, or pressure, is about 1000 Millibars (mb), but atop Mount Everest it is only about 330 mb (it's only ever been measured once so far, by the way). With less air to move, the apparent suction of a vacuum cleaner on Everest will be noticeably less than at sea level.

Why? Well,  back to air flow: The fan isn't actually sucking air through the vacuum cleaner. It's just trying to remove it from the machine. What's actually happening is that the atmosphere is pushing air into the machine to replace the air that the fan is pulling out. Anything in the way of the moving air will get blown along with the air flow, provided it is light enough to be moved by the force of the air flow. We understand the force of the air flow better if we call it suction. The amount of apparent 'suction' that a vacuum has can never be greater than the pressure of the air around it.

But you can adjust the speed of the air flow.

The same fan running at the same speed but with larger openings (both inlet and exhaust) moves the same amount of air as one with smaller openings, but at slower speeds. We know that objects (air, in this case) have weight (mass) and that when multiplied by speed (velocity), the force (pressure) that the object has increases as  a result.  Making the inlet smaller increases speed, and thus increases the apparent pressure, or "suction".

We have all seen some kind of advertising gimmick where the vacuum cleaner is tested by  lifting a bowling ball or some other heavy object. Sometimes they'll even show the stunt when the vacuum cleaner is full of dirt. In every case, some kind of attachment ensures a perfect seal on the object to be lifted. Any vacuum cleaner that isn't clogged so much as to cut off all air flow or one that has a leak in the inlet can perform this stunt. It is the attachment (a suction cup, typically) that gets pressed onto the object by the atmosphere: which is trying to equalize itself with the other side of the suction cup, and is doing all the work. The correct measure for the stunt should be how fast the vacuum cleaner creates the void inside the attachment.

It is a balance between the air flow and speed of the air through the vacuum cleaner's attachments or nozzles that actually matters. A poorly designed vacuum system with unbalanced measurements will not be as effective as one that has been designed with properly balanced parts.


The Electrolux Automatic Vacuum Cleaner


The Dial on the front of almost all Electrolux Vacuum Cleaners adjusts when the bag compartment's door 'pops' open, based on how full the bag is.
 The engeniers who design and build vacuum cleaners (should) know all about this balance, and the folks at Electrolux designed a rather nifty mechanism that uses this balance to shut the vacuum cleaner off when the bag got so full as to impede the air flow. This purely mechanical mechanism first appeared on the Model  LX (60) and soon became standard on all their machines.

A simple set of springs, bellows (like a suction cup) and tubes that balanced the latch on the door to the bag compartment. When the bag gets too full, the door pops open. Since the power switch is linked to the door, the vacuum cleaner also turns off, automatically, letting you know that it is time to change the bag.

To the credit of the Electrolux engineers, they devised a way to adjust when the system pops the door. The LX model used a "basement and attic key" that gets inserted into a slot that prevents the mechanism from working at all, while later models have a dial you can adjust. A dial on the cleaner can be set based on the type of cleaning you are doing.

Simply set the dial to a lower number for larger and or lighter debris: If you are cleaning large fluffy stuff (threads, lint, etc) it will fill the bag quicker. If you are cleaning a dusty room, like an attic, set the dial higher. For most household cleaning you should have your machine set for about 4 or 5 (out of 6).

The setting you select should alow the bag to nearly fill up all the way- but remember: you do not want the bag to fill completely, as it will damage the motor over time. 


How the Automatic System Works

The automatic sysstem simply balances the amount of air flow between the motor and the hose inlet. If the amount of air flow at the hose inlet is reduced enough a spring releases the door. A small hose connects the mechanism in the door with an inlet near the motor.

If you have an Automatic cleaner that the door doesn't stay closed, there is probably a simple explanation for this, and a solution that is easy to do. It is probably due to a clog in this mechanism. A visual inspection and a little bit of cleaning might solve any problems this mechanism may have.

First you should check the rubber seal of the motor hoseinside the bag compartment. It should be clean, soft and pliable. If it is clogged, a toothpick can be carefully poked in it to clean it out. If the seal is dry and cracked, then the system might be leaking. There is little than can be done to fix this other than hunt down another  electrolux with the same part. I doubt that many vacuum cleaner repair shops have these any more- but it might be worth an email.


The inside of the bag compartment door should be clean and free of rust. It should also be smooth and shiny. Any dents or bent metal might cause an impropper seal.

The next thing to check for is the little hole that the above seal connects with- again, clean and free of any cloggs. You can see this in the bottom of this picture on the right.
If these are OK and the door doesn't stay closed, then you may need to have the unit serviced. You can and should first take a look inside the door to be sure of what's going on in there.

Simply remove the three screws (other models may have more or less) and gently lift off the inside cover. Be sure to remember which screws go where- and don't loose them.


Now that you have the cover open, you can see what's going on inside. First look at the hoses: they should be clean, flexable, without any cracks, and -of course- connected.

If any are damaged or missing, you might try using the tubing that you can get for aquarium toys- or other similar tubing. The tubing must be thick enough as to not collapse, as a small vacuum is generated in them.
I was very lucky: My Automatic G came nearly as you see here. I did take apart all the pieces and cleaned them up al bit. A mild dishwashing solution with warm water and a good rinse can do wonders. Allways allow parts to thouroughly dry before you put them back together.

You can see that these parts are attached by only a few screws, but there are some springs involved. Study and know where everything goes before you take it appart.



Last to inspect is the Dial Control, seen at the bottom. A little dust inside shouldn't cause major problems, but it might be an indicator of problems inside.

The dial is attached to a spring loaded valve. This valve diverts air pulled through the mechanism from the Hose Inlet tube to the Motor's tube.

If the bag is empty, the the amount of air flowing through the Hose Inlet tube balances with the air flowing through the Motor's tube.
As the bag fills up, the motor's airflow becomes greater, and that moves the valve to close off the airflow from the Hose Inlet tube and then sucks the Catch Release bellows, popping the door open.

It's based on a balance of air flow compared between the inside of the bag and the outside of the bag. As long as both sides are equal, the catch stays locked. That's why the door stays closed when the cleaner is off, and when you cover the hose with your hand- in eather case, the amount of air flow is the same on both sides.
 
Now why does the motor go faster when you stop up the hose? hehehe....
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