Understanding the Differences between Carbon Brushes in the Clarke 7R and B-2+ Edgers

The American Sanders Super 7R and B-2+ Edgers (formerly Clarke) are both time-tested machines that give great results. They are quite well known throughout the industry. However, there are a few key differences between the two edgers. The most significant difference is the number of carbon brushes in each machine. Carbon brushes simply transfer power from the stationary part of the edger to a rotating part. The American Sanders Super 7R Edger offers four carbon brushes, while the B-2+ Edger is equipped with two.

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The American Sanders Super 7R Edger’s four-pole (4-carbon brush) motor naturally promotes more torque than the B-2+ Edger’s two-pole (2-carbon brush) motor. The rotating mechanism in the 7R (armature) has more copper bars in the commutator that the brushes ride on. The unit’s four carbon brushes also allow for fewer brush changes and can result in less maintenance on the motor.  A four-pole (4-carbon brush) motor, when geared the same, will run at slower RPM than a 2-pole (2-carbon brush) motor of the same gear ratio.  The B2 edger is a 2-pole (2-carbon brush) motor and will run at a higher RPM, as is evidenced by the B-2’s dual speed capability. The Super 7R is a single speed motor compared to the B-2+’s dual speed motor. However, the four carbon brushes make it so the performance of the motor is comparable to the B-2+’s.

There are some other differences between the Super 7R and B-2+. The Super 7R features a 7/8″ center hole. The size of the center hole reduces the chance of unwanted scratches when the pad wears down. The large fan creates a great dust pick up without attaching an external hose. The independent caster wheel assembly makes for easier adjustments to the cut on the floor. There’s no need to flip the machine over.

The B-2+ is dual speed allows the mechanic to adjust to different speeds while using different grits of sandpaper. The extra weight of the machine reduces the amount of physical force a mechanic would need to sand difficult to remove areas. The B-2+ is bit higher of a machine. If the mechanic doesn’t have to bend over as far, it’s easier on his back.

Both American Sanders edgers produce incredible results. Whichever machine you decide to go with, you’ll be satisfied knowing that it’s an edger that you can rely on for lasting quality and outstanding sanding results.


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