rack and pinion: a wheel gear (the pinion) meshes with a toothed rack; converts rotary to reciprocating motion (and vice versa)
gear: a toothed wheel that engages another toothed mechanism in order to change the speed or direction of transmitted motion
hydrochlorofluorocarbon: a fluorocarbon that is replacing chlorofluorocarbon as a refrigerant and propellant in aerosol cans; considered to be somewhat less destructive to the atmosphere