a simple machine consisting of a circular frame with spokes (or a solid disc) that can rotate on a shaft or axle (as in vehicles or other machines)

tooth on the rim of gear wheel

one of a number of uniform projections on a gear

gears that mesh at an angle

gear that engages a rocking lever

a gear with a small number of teeth designed to mesh with a larger wheel or rack

an outer gear that revolves about a central sun gear of an epicyclic train

a wheel gear (the pinion) meshes with a toothed rack; converts rotary to reciprocating motion (and vice versa)

tooth on the rim of gear wheel

one of a number of uniform projections on a gear