How does a bagless vacuum cleaner work?

Most modern vacuums have done away with bags and use easy-to-empty plastic bins instead. That means they need to use filters to separate the dust from the air (which is the job the bag used to do). Here's the setup in a typical modern, bagless Electrolux cleaner. You'll notice that the airstream, which I've indicated with a large yellow arrow, is linear (a straight line) from the hose at the front through to the grille at the back, just as it is in an old-style bag cleaner.

1. Inlet: This attaches to the usual cleaning head and interchangeable tools (not shown).

2. Dirt collecting bin: Normally this sits inside the cleaner at the front, but I've removed it and placed it on its side so you can see things more clearly.

3. HEPA filter: The filter is a cylinder of folded paper attached to the orange bit you can see at the base of the dirt bin. The air is sucked through the filter, leaving the dirt behind in the bin. You can see some photos of the actual filters from this machine in our article on HEPA filters.

4. Motor unit: This cleaner has a very powerful 2000-watt motor, although it does need it to pull air through the HEPA filter. Motor ratings for cleaners with HEPA filters can be quite misleading: they don't necessarily give you more suction at the cleaning end, because more of their power is used pulling air through the filter, which may clog frequently.

5. Filter and outlet grille: This is a simple bit of sponge that you can remove and wash.