My vacuum smells like it's burning. What should I do?
Stop using the vacuum immediately to prevent further damage. There is a good chance that your carbon brushes are completely worn out and that the conductor wire inside the brushes is starting to damage the motor's rotor. At this point, it is preferable to replace the entire motor unless a visual inspection indicates that the motor can be rebuilt by resurfacing the rotor and installing a new set of carbon brushes.
My central vacuum is making a very loud noise. What should I do?
An extremely loud motor noise is generally a sign that the ball bearings are failing or beginning to seize. We recommend stopping the vacuum immediately and having the motor inspected. Once the motor has cooled sufficiently, manually turning the motor's rotor should provide a good indication of the condition of the ball bearings. If there is obvious rubbing or if small balls are present inside the vacuum motor housing, the motor should normally be replaced completely or rebuilt.
When should the carbon brushes on a vacuum motor be replaced?
Normally, the carbon brushes in a vacuum motor should be replaced before reaching the critical stage of 90% wear or when approximately 3/16" of carbon remains. Replacing the carbon brushes is preventative maintenance that should be performed to avoid damaging other components, such as the rotor or armature. The rotor, also called the armature, is the central component that rotates.
Most carbon brushes have a small conductor wire inside the carbon portion. This small conductor wire can scratch the armature and permanently damage it. When an armature is damaged, the motor runs erratically and the amperage is generally no longer stable. In addition, a damaged rotor surface, with small notches in the metal, can cause newly installed carbon brushes to deteriorate prematurely.
For small surface scratches on the rotor or armature, a small stone can be used to sand or smooth the rotor surface. This small stone can help extend the life of your motor.
How long will my motor last after replacing the carbon brushes?
First of all, it is important to know that a standard 5.7" diameter motor with at least two stages (two fans), from brands such as Lamb Ametek, Domel or Electro Motor, should last an average of 800 hours.
When the original set of carbon brushes is completely worn out, and depending on the wear of the rotor and ball bearings, a motor should be able to run for approximately another 400 hours after the first set of brushes has been replaced.
Overall, a motor of this type should not last more than 1,200 hours, with preventative replacement of the original brushes at around 700 hours.
Some motor and vacuum manufacturers even recommend replacing the brushes every 500 hours of use.
Why wouldn't my vacuum motor last through more than two sets of carbon brushes?
Carbon brushes are not the only motor components that experience normal wear. There is also wear on the rotor (armature) and the ball bearings.
Armature (Rotor) Wear
The armature wears down through contact with the carbon brushes. An arc or groove develops in the rotor metal where the brushes make contact. Over time, the groove becomes so pronounced that the armature needs to be replaced. The cost of the armature, along with the time required and the complexity involved in disassembling and reassembling the motor, generally makes this repair less worthwhile from a cost-to-benefit standpoint. In addition to the armature, a complete rebuild requires replacing the ball bearings and installing a new set of carbon brushes. The cost of a new motor and the ease of replacing only the motor are often two factors that lead customers and specialized technicians to replace the entire motor instead.
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Ball Bearings
Ball bearings, also commonly called bearings, are another potential cause of vacuum motor failure. Normally, after two sets of carbon brushes, the next components likely to fail are the ball bearings. Replacing the two ball bearings is a delicate procedure that requires specialized tools. In addition, if you are replacing the ball bearings, it would be preferable to also replace the rotor and carbon brushes as part of a complete rebuild. As mentioned above, rebuilding the motor is not always worth the hassle, and most technicians prefer to replace the entire motor.
Can the brushes be replaced on a small vacuum motor?
The short answer is yes. Yes, if the parts are available, as they are not always available.
Smaller-diameter motors, such as 4.5", 4.7", 5" and 5.25" motors, have a shorter service life because, in addition to being smaller, they generally have only one stage (one fan). Because they are smaller and have only one fan, they must spin faster to produce sufficient suction power. The stress placed on these small motors at high rotational speeds is often the cause of premature ball bearing wear. Generally, the ball bearings will be the first components to fail. The service life of some of these motors can be as short as 250 hours. This is the case with most motors found in vacuums sold in big-box stores or hardware stores, even when they carry a well-known brand name.
The small motors found in Shop-Vac-type wet/dry shop vacuums are generally unbranded motors made in China, with no replacement parts available. This is why large quantities of these machines end up being discarded because they cannot be repaired.
How can I tell if my vacuum motor can be repaired?
The best thing to do is email us photos of your motor, along with its brand and model. Please take the time to include all the numbers you can find on the appliance as well as on the motor itself.
Here is an example of the information we need:
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Call us for more information:
1-888-908-0962
or
Send us your photos and information at this email address:
