Frictional gearing

Frictional \Fric"tion*al\, a.
   Relating to friction; moved by friction; produced by
   friction; as, frictional electricity.
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   {Frictional gearing}, wheels which transmit motion by surface
      friction instead of teeth. The faces are sometimes made
      more or less V-shaped to increase or decrease friction, as
      required.
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Gearing \Gear"ing\, n.
   1. Harness.
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   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.
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   {Frictional gearing}. See under {Frictional}.

   {Gearing chain}, an endless chain transmitting motion from
      one sprocket wheel to another. See Illust. of {Chain
      wheel}.

   {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.
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