506 Section 5 Electrical and Electronic Systems Technology
Frames
The frames, or housings, are the three main sec-
tions of the starting motor. The frames hold the
other components. The center frame, or fi eld frame,
is the large steel cylinder that holds the fi eld wind-
ings or fi eld magnets. The two end frames fasten to
each end of the center frame.
The drive end frame is the housing around the
starting motor pinion gear. The drive end frame
contains a bushing for the armature shaft. The shaft
spins inside this bushing. The drive end bushing
helps keep the pinion gear properly meshed with
the fl ywheel ring gear.
The brush end frame usually holds the brushes
and brush springs around the armature commutator.
It bolts to the end opposite the drive gear. Two long
bolts commonly fi t through the brush end frame and
thread into holes in the drive end frame. This holds
both end frames securely onto the center frame.
Planetary gear
reduction assembly Armature
Permanent
field magnets
Brush
Overrunning
drive
Drive end
frame
Roller
bearing
Sealed
ball bearings
Brush end
frame
Electrical
connections
Solenoid coil
Plunger
Solenoid return
spring
Shift mechanism
Solenoid
Figure 30-5. Observe a cutaway of a typical starting motor. Note that this motor uses permanent magnets instead of fi eld windings.
Brushes
Iron cores
Field coils
Commutator
Center frame
N
N N
S
S
S
Magnets contain
iron, boron, and
neodymium
Center frame
Strong
stationary
field
Figure 30-6. This starter uses fi eld windings wrapped around
iron pole shoes. Current through the coils produces a powerful
magnetic fi eld that acts on the armature.
Figure 30-7. This starter does not need fi eld windings.
It uses permanent magnets that are strong enough to rotate
the armature.