attached to, the frame or one end bell of the machine.
Use the grade of brush shown on the drawing or in
Flexible leads (pigtails) are used to connect the brushes
the technical manual applicable to the machine, except
to the terminals of the external circuit. An adjustable
where Naval Sea Systems Command instructions issued
spring is generally provided to maintain proper pressure
after the date of the drawing or technical manual (such
of the brush on the commutator to effect good
commutation. Atypical dc generator brush holder and
as the instructions for brushes to be used in electric
brush-rigging assembly is shown in figure 7-10.
propulsion and magnetic minesweeping equipment
dictate otherwise. In such cases, follow the Naval Sea
Brushes are manufactured in different grades to
meet the requirements of the varied types of service. The
Systems Command instructions. Most of the brushes in
properties of resistance, ampere carrying capacity,
shipboard service appear on the Qualified Products List
as complying with one of six military grades (S, A, H, D,
determined by the maximum allowable speed and load of
G, and E). For propulsion and magnetic minesweeping
the machine.
equipment, only one grade of brush specified by the
CORRECT BRUSH TYPE
manufacturer is permitted. The restriction on brush
interchangeability is due to the vital nature of the
The correct grade of brush and correct brush
machines involved.
adjustment are necessary to avoid commutation trouble.
Figure 7-10.--Brush holder and brush rigging assembly.
7-9
