In recent times there has been a lot of chatter about ‘brushless motors’ among those in the world of power tools, and even other technology such as vacuum cleaners and hand driers, but just what are brushless motors and what makes them so much better than the motors traditionally found in these items?
Well first things first, we should point out that the technology isn’t anything new, it’s existed in the heavy industrial machine industry since the 1960s, but only in recent times have brushless motors made the jump to power tools, with some high profile examples from Milwaukee and Makita making the headlines.
Manufacturers would have us believe at least that brushless motors add to the performance and reliability of power tools, but to understand why we need to know how they differ from the older ‘brushed motor’ design.
How Brushed Motors Work
A typical brushed motor uses magnets and brushes that are fixed to the motor housing and a commutator and armature that rotate about the motor shaft. When electricity is passed through the motor circuit the charge passes through the brushes and onto the commutator, and then the the copper winding of the armature. The charged commutator becomes magnetized and acts against the fixed magnets thereby allowing the motor shaft to rotate.
How Brushless Motors Work
By contrast brushless motors do away with the both the brushes and the commutator and the fixed magnets instead take up residence on the motor shaft and the armature is now fixed in the perimeter. A clever piece of electronics works in place of the brushes and commutator, delivering charge to the armature. Perhaps more crucially the electronic element is able to adjust the amount of energy consumed by the motor, explaining why these power tools are marketed as being ‘smart’. The tool will sense the level of mechanical resistance being applied by the user and adjust the power accordingly.
Brushless motors also have the potential to be more powerful overall. Having the copper windings of the armature mounted on the outside of the motor arrangement means that they can be made larger, and the absence of the brushes mean that there is no friction to make the motor run inefficiently.
Is this the end for brushed motors?
Unlikely. Whilst there is no denying the superior design and performance of a brushless motor, the technology behind it comes at a price. You can expect to pay anything up to 5 times the price for a tool with a brushless motor compared to one with a brushed motor, so whilst they might make good financial sense to professional tradesman who require reliable performance day in day out, for the average DIY level user they aren’t going to be taking the place of brushed motors altogether any time soon.
