K 2500 Truck 4WD V8-454 7.4L VIN J SFI (1997)
28-MT Series Components
Three starter motors are used on these engines. The SD-255 and 260 is a straight drive starter with the pinion driven directly by the armature shaft. Pole
pieces are arranged around the armature that is energized by wound field coils. This type is used on gas engines.
The PG-260 achieves gear reduction at a ratio of 5:1 through planetary gears. Its relatively small size and light weight offers improved cranking
performance and reduced current requirements for larger gasoline engines.
The 28-MT used on diesel engines, is a gear reduction starter with an overrunning roller type clutch and an enclosed shift lever.
Enclosed shift lever cranking motors have the shift lever mechanism and the solenoid plunger enclosed in the drive housing, protecting them from
exposure to dirt, icing conditions, and splash.
Solenoid windings are energized when the ignition switch is in the start position. The resulting plunger and shift lever movement causes the pinion to
engage the engine flywheel ring gear, the solenoid main contacts to close, and cranking takes place. When the engine starts, the pinion overrunning
clutch protects the armature from excessive speed until the ignition switch is released. At this time the plunger return spring causes the pinion to
disengage. To prevent excessive overrunning, release the switch from the crank position as soon as the engine starts.
