Brush.
In electric current generators and motors, the pieces of copper or other
material that bear against the cylindrical surface of the commutator are
thus termed. Many different constructions have been employed. Some have
employed little wheels or discs bearing against and rotating on the
surface of the commutator. A bundle of copper strips is often employed,
placed flatwise. Sometimes the same are used, but are placed edgewise.
Wire in bundles, soldered together at their distant ends have been
employed. Carbon brushes, which are simply rods or slabs of carbon, are
used with much success.
Synonym--Collecting Brush.
Brush, Carbon.
A brush for a dynamo or motor, which consists of a plate or rod of
carbon, held in a brush holder and pressed against the commutator
surface.
Brushes, Adjustment of.
In electric current generators and motors, the brushes which bear upon
the commutator when the machine is in action need occasional adjustment.
This is effected by shifting them until sparking between them and the
commutator is nearly or quite suppressed.
Fig. 68. BRUSH HOLDER.
Brushes, Lead of.
In a dynamo electric generator, the lead or displacement in advance of
or beyond the position at right angles to the line connecting the poles
of the field magnet, which is given the brushes. In a motor the brushes
are set back of the right angle position, or are given a negative lead.
(See Lag.)