WordNet sense 1 (wheelwork consisting of a connected set of rotating gears by which force is transmitted or motion or torque is changed):

train, gearing, geartrain, power train

WordNet sense 2 (a mechanism for transmitting motion for some specific purpose (as the steering gear of a vehicle)):

gear mechanism

WordNet sense 3 (equipment consisting of miscellaneous articles needed for a particular operation or sport etc.):

appurtenance, paraphernalia

WordNet sense 4 (a toothed wheel that engages another toothed mechanism in order to change the speed or direction of transmitted motion):

cogwheel, geared wheel

WordNet sense 5 (set the level or character of):

pitch