Brushed motors have driven blower, fan, grinder and vacuum designs for more than 100 years. They remain more relevant than ever as their core strengths — simplicity in control, cost-effectiveness, reliability and high peak torque outputs — are continually complemented by innovations that extend useful life and applicability.
Consider universal motors from the Lamb division of AMETEK Dynamic Fluid Solutions (DFS), mass-customized for use in an array of consumer and commercial-grade appliances. As AMETEK DFS application engineering manager Kevin Martin explains, these are universal drive motors — brushed motors — with field winding and armature in series.
Such motors deliver high starting torque, a characteristic useful particularly for grinding and mixing machines in particular. The magnetic path through the motor includes lamination stacks that minimize eddy currents that arise upon power input. Speeds range from a thousand or so rpm to many times higher, also useful in designs that might run as much as 30,000 rpm at their fastest.
Of course, one mechanical wear point occurs at the rotor’s commutator interface with the brushes. But brushes are one of the few motor subcomponents that you can easily change yourself.
How to Change the Brushes
- Follow the steps below to change the brushes on a 5.7-in. vacuum motor.
- Remove power from the motor.
- With a flat blade screwdriver, bend back the metal safety clips so they’re no longer over the plastic cap.
- Use a screwdriver to pry up on the plastic cap — to pop the cap loose. (Once the cap has been removed the brush mechs are exposed.)
- Use the flat blade screwdriver and locate the brush clip, and using the screwdriver press down firmly and push the clip towards the center of the motor. (The clip should slide out from under the black nylon of the brush mechanism.)
- When the clip is free from the brush, remove the two screws holding the brush clamp in place.
- Lift the clamp up and remove the brush.
- Now install the new brush and start the brush clip into the nylon.
- Use the top bracket of the motor to press the clip all the way into place.
- Secure the brush clamp back in place using the two screws. Repeat this for the second brush
- Press the black plastic cap back into place until both sides click. Then bend the metal safety clips back so that they help hold the plastic cap in place.
One caveat is that brushed can’t be changed an infinite number of times because the commutator upon which they ride is also a wear item. The general rule of thumb is that brushes can be changed two or three times before the commutator on the rotor reaches the end of its useful life — and renders the motor itself unserviceable.
At AMETEK Dynamic Fluid Solutions, we understand you’re looking for more than just an off-the-shelf part or one-time solution. You need a true technology partner who understands your engineering challenge that is focused on you, providing customized, collaborative solutions. We’ll also provide you with excellent customer service for a great total experience.