Electric motors send current though copper coils embedded in a steel ring, generating a magnetic field that spins an electromagnetic rotor inside. The ring is typically a single piece of metal. Copper coils are inserted through a gap into slots on each side of the ring, and then slid into place. DeWalt instead uses a four-piece steel ring and assembles it around larger coils, eliminating the need for a gap and making room for more power-producing copper. The motor is now in two new half-inch drills and a handheld grinder, but it could easily migrate to any tool that needs some extra kick.
