These are extraordinary in their durable designs and construction as well as their high filtration capabilities. Since most vacuum cleaner literature doesn't specify how many fans the suction motor has, you'll need to depend on a knowledgeable vacuum cleaner technician like those at Ristenbatt Vacuum Cleaner Service to tell you which vacuum cleaners use the more durable multi-fan design. The filtering system of a vacuum cleaner performs two functions. The first is to efficiently remove almost all of the dust and allergens from the air which you breath as discussed in our articles on Air Filtering Efficiency and HEPA and Micron Filtration. The other is to keep the motor in a clean-air system as clean as possible.
Dirt is abrasive by nature and increases the wear on the various motor parts.
Excessive dirt in the suction fans can even cause them to pull apart due the increased centrifugal force exerted on their fins. Excessive vibration of a suction motor can be caused by the uneven dirt deposits in the fins. Look closely at the filter or filters which are between the paper bag and the motor. The pores for the air to pass through should be a small as possible. Plain foam rubber tends to be the worst type of filter while the electrostatic filter is the best.