and sustaining, at the angle formed by their circumferences, the pivot or journal of a revolving shaft, to
relieve it of friction; — called also friction wheels. — Friction balls, or Friction rollers, balls or rollers
placed so as to receive the pressure or weight of bodies in motion, and relieve friction, as in the hub of
a bicycle wheel. — Friction brake (Mach.), a form of dynamometer for measuring the power a motor
exerts. A clamp around the revolving shaft or fly wheel of the motor resists the motion by its friction, the
work thus absorbed being ascertained by observing the force required to keep the clamp from revolving
with the shaft; a Prony brake. — Friction chocks, brakes attached to the common standing garrison
carriages of guns, so as to raise the trucks or wheels off the platform when the gun begins to recoil, and
prevent its running back. Earrow. — Friction clutch, Friction coupling, an engaging and disengaging
gear for revolving shafts, pulleys, etc., acting by friction; esp.: (a) A device in which a piece on one shaft
or pulley is so forcibly pressed against a piece on another shaft that the two will revolve together; as,
in the illustration, the cone a on one shaft, when thrust forcibly into the corresponding hollow cone b
on the other shaft, compels the shafts to rotate together, by the hold the friction of the conical surfaces
gives. (b) A toothed clutch, one member of which, instead of being made fast on its shaft, is held by
friction and can turn, by slipping, under excessive strain or in starting. — Friction drop hammer, one
in which the hammer is raised for striking by the friction of revolving rollers which nip the hammer rod.
— Friction gear. See Frictional gearing, under Frictional. — Friction machine, an electrical machine,
generating electricity by friction. — Friction meter, an instrument for measuring friction, as in testing
lubricants. — Friction powder, Friction composition, a composition of chlorate of potassium, antimony,
sulphide, etc, which readily ignites by friction. — Friction primer, Friction tube, a tube used for firing
cannon by means of the friction of a roughened wire in the friction powder or composition with which the
tube is filled. — Friction wheel (Mach.), one of the wheels in frictional gearing. See under Frictional.
Frictional
(Fric"tion*al) a. Relating to friction; moved by friction; produced by friction; as, frictional electricity.
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.
Frictionless
(Fric"tion*less), a. Having no friction.
