Key ideas1 of 3
Teeth transfer the force
Gears are toothed wheels that rotate about fixed axes. At the contact between meshing teeth, one gear exerts a force on the other, producing a moment about its axle. Two directly meshing external gears rotate in opposite directions. The driver is the gear receiving the input turning effect; the driven gear receives the output. The arrows show rotation, not straight-line movement of the axles.
