“Brushless motor” seems to be the newest power-tool buzzword these days. It may seem like nothing more than some marketing, but unlike the 18v/20v marketing gimmick, there are some real benefits with these new motors.
A Little Background
To understand what a brushless motor is, it helps to look at a standard brushed armature motor.
In the side picture, the “brushes” are the yellow and light-blue upside-down-L shaped components. As the brushes feed electricity to the armature in the center, the motor spins. The brushes drag along the spinning contact so that there is always a complete circuit.
As the armature spins, the brushes contact different points on the rotor and the electric current flips directions, in turn flipping the magnetic field in the armature. This repeated magnetic reversal propels the armature around and around.
The physical contact on moving parts causes wear along with energy loss to heat from friction. Over time, the brushes will wear and cause decreases in performance.
In quality tools, the brushes are accessible and replaceable at a modest cost, allowing owners to greatly extend the tool life.
How Brushless Is Different
The armature coils are positioned around the outside, and the permanent magnets are placed on the rotor in the center. By doing this, the parts that spin don’t need any electricity and therefore no brushes are required.
Magnetic field reversal is also different with brushless. By using electronics to control the current flow, a more precise and efficient use of power is achieved.
Brushless Impact Drivers
There are currently a number of manufacturers who have built – or are planning to build – cordless impact drivers with brushless motors.
Others are focusing on increases in battery life or longer tool life due to decreased wear on the components.
Brushless impact driver list
|Milwaukee 2653||18v||1600 in-lbs||0–2900 rpm||0-3600 ipm|
|DeWALT DCF895||18v||1500 in-lbs||0–2850 rpm||0-2700 ipm|
|Makita LXDT01||18v||1460 in-lbs||0–2600 rpm||0-3200 ipm|
|Makita LXDT06||18v||1500 in-lbs||0–2800 rpm||0-3200 ipm|
|Makita LXDT08||18v||1420 in-lbs||0–2500 rpm||0-3200 ipm|
|Hitachi WH18DBL||18v||1420 in-lbs||0–2600 rpm||0-3200 ipm|
|Hitachi WH14DBL||14.4v||1330 in-lbs||0–2600 rpm||0-3200 ipm|
More Info About Brushless Motors
While researching these motors, we found that the guys over at ToolGuyd.com already wrote a great in-depth article we have no need to rewrite. Check out their Brushless Motors 101 for more details on how they work, or see the full resource list below.