Abstract: A multi-speed, power-driven tool may include a transmission mechanism that transmits power from a motor to an output device. A speed selection mechanism may be coupled to the transmission mechanism, to control a speed reduction through the transmission mechanism, and an output speed of the tool. The transmission mechanism may employ a compound, stepped, planetary gear assembly, to provide for an axially compact arrangement of transmission mechanism components, to reduce an axial length of the tool. The speed selection mechanism may employ a multi-staged grounding device, corresponding to the reduced axial length of the transmission mechanism.

Abstract: A sander may include a housing, a motor, a sanding platen, and a two-piece fan. The motor may be disposed within the housing and may include an output shaft. The sanding platen may be driven by the motor for movement relative to the housing. The fan may be driven by the motor and may include a first piece formed from a first material and a second piece formed from a second material. The first piece may include a disk-shaped body having first and second opposite sides. The first side may include a plurality of first blades extending therefrom. The second side may include a plurality of second blades extending therefrom and a recess formed therein. The second piece may be received in the recess and may include a counterweight boss formed thereon.

Abstract: A drive mechanism for a hammer drill comprises a hollow piston 558 having a cylindrical bearing that is adapted to receive a crank pin in order to cause the hollow piston 558 to reciprocate inside a spindle 548. A plurality of longitudinal ridges 559 are formed on the outer surface of the hollow piston 558 to reduce the surface area of contact between the hollow piston 558 and the spindle 548, and a plurality of grooves 561 are formed in the gaps between the ridges. The grooves 561 are adapted to retain lubricant 563 in order to reduce frictional contact between the hollow piston 558 and the spindle 548.