In principle, the design of internal gear teeth is the same as that for spur gears. Any of the basic rack forms used for spur gears may be applied to internal gears. The internal gear drive, however, ...

WHEN PINIONS OF SMALL TOOTH NUMBERS ARE REQUIRED FOR SUCH APPLICATIONS AS MOTOR STARTING PINIONS OR LARGER REDUCTION RATIOS IN A SINGLE REDUCTION, UNDERCUT MAY BE MINIMIZED AND AN EFFECTIVE DRIVE ...

An outer ring gear has ten pairs of magnets, making the ratio of “teeth” between the two gears ... be a refinement on [Retsetman]’s earlier design, and while he provides no build files ...

Gears can change the direction or the speed of movement. As there are teeth around the edge of the gears they grip together and so can withstand a greater force, enabling them to move large items ...