Automotive Electrical and Electronic Systems Classroom Manual Fifth Edition Update by John F. Kershaw

198 Chapter Nine
Figure 9-36.
Armature wave winding.
Figure 9-38.
Systems)
A four-brush motor. (Delphi Automotive
Figure 9-37. The pinion gear meshes with the flywheel
ring gear.
the motor field circuit, which in turn eliminates the
potential for field wire-to-frame shorts, field coil
welding, and other electrical problems. The motor
has only an armature circuit. Because the smaller
armature in permanent magnet starters uses reinforcement
bands, it has a longer life than the armature
in wound-field starter motors.
The magnetic field of the starter motor is provided
by four or six small permanent magnets.
These magnets are made from an alloy of iron and
rare-earth materials that produces a magnetic field
strong enough to operate the motor without relying
on traditional current-carrying field coil windings
around iron pole pieces. Removing the field circuit
not only minimizes potential electrical problems,
the use of permanent-magnet fields allows engineers
to design a gear-reduction motor half the size
and weight of a conventional wound-field motor
without compromising cranking performance.
See Chapter 9 of the Shop Manual for service
and testing.
STARTER MOTOR
AND DRIVE TYPES
Starter motors, as shown in Figure 9-39 are
direct-current (DC) motors that use a great
amount of current for a short time. The starter
motor circuit is a simple one containing just the