The Collaborative International Dictionary of English v.0.48:
Gearing \Gear"ing\, n.
2. (Mach.) The parts by which motion imparted to one portion
of an engine or machine is transmitted to another,
considered collectively; as, the valve gearing of a
locomotive engine; belt gearing; esp., a train of wheels
for transmitting and varying motion in machinery.
Frictional gearing. See under Frictional.
Gearing chain, an endless chain transmitting motion from
one sprocket wheel to another. See Illust. of Chain
Spur gearing, gearing in which the teeth or cogs are ranged
round either the concave or the convex surface (properly
the latter) of a cylindrical wheel; -- for transmitting
motion between parallel shafts, etc.