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| Illustration 1 | g00583663 |
Starting Motor Components (1) Housing (2) Armature (3) Brushes (4) Brush holder (5) Case of the starting motor (6) Frame (7) Armature reduction gear (8) Idler reduction gear (9) Field winding (10) Overrunning clutch gear (11) Pinion gear (12) Overrunning clutch (13) Solenoid switch | |
The major components of the reduction starting motor are the following items:
- Case of the starting motor (5)
- Field winding (9)
- Armature (2)
- Brushes (3)
- Brush holder (4)
- Gears (7), (8) and (10)
- Pinion gear (11)
- Overrunning clutch gear (12)
- Solenoid switch (13)
The reduction starting motor operates differently than the conventional starting motor. Solenoid (13), overrunning clutch gear (12) and pinion gear (11) are mounted below armature (2) and field winding (9). When the starting motor is activated, armature reduction gear (7) will turn clockwise. Idler reduction gear (8) will turn counterclockwise and overrunning clutch gear (10) with pinion gear (11) will turn clockwise. The reduction gears (7) and (8) reduce the speed of the armature. The speed of the armature is reduced by 25 percent to 33 percent of the pinion gear (11).
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| Illustration 2 | g00583704 |
Field Winding And Case Of The Starting Motor (5) Case of the starting motor (9) Field winding | |
The case of the starting motor (5) supports the field winding (9), the brush holder and the brushes. The two positive brushes are welded to the field winding leads. Field winding (9) provides the magnetic field for the armature.
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| Illustration 3 | g00583707 |
Armature (2) Armature. | |
Armature (2) consists of a laminated iron core which is assembled on the armature shaft. The commutator is at one end of the armature. The commutator is constructed with segmented bars of copper. The segmented bars are insulated from each other and the armature shaft. The armature windings are wound in the slots of the core. The windings are then connected to the commutator segments. Bearings support the armature and the field winding in the case of the starting motor. The armature and the field winding are connected in series. The equal current flow generates high torque especially when the motor is first started.
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| Illustration 4 | g00583770 |
Brush Holder (3) Brushes (4) Brush holder (14) Brush springs | |
Brush holder (4) is mounted over the commutator to the case of the starting motor. Four brushes are held against the commutator. Brush springs (14) keep pressure on the brushes so the brushes stay in contact with the commutator. Brushes (3) are made of carbon which is a good conductor of electricity. The brushes transmit current from the field winding to the commutator. There are four brushes. Two of the brushes are positive. The positive brushes are welded to the field winding leads. Two of the brushes are negative. The negative brushes are grounded to the case.
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| Illustration 5 | g00583773 |
Overrunning Clutch (10) Overrunning clutch gear (11) Pinion gear (12) Overrunning clutch | |
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| Illustration 6 | g00583774 |
Overrunning Clutch Components (10) Overrunning clutch gear (11) Pinion gear (12) Overrunning clutch (15) Clutch roller (16) Roller spring | |
The overrunning clutch consists of the following items:
- Pinion gear (11)
- Overrunning clutch gear (10)
- Clutch rollers (15)
- Roller springs (16)
- Ball bearings
The outer roller clutch operates in the same manner as the clutch that is used in the conventional starting motor. Screw splines that are cut on the pinion shaft allow the pinion gear to advance while the pinion shaft is rotating. The screw splines are used instead of using a shift lever to move the pinion. As the engine starts to run, the engine speed eventually exceeds the starting motor speed. Overrunning clutch (12) protects the starting motor from an overspeed condition by disengaging the mechanical connection between the engine flywheel and the starting motor. Pinion gear (11) engages the flywheel ring gear. If butt engagement results, the pinion gear will stop. As a result, the overrunning clutch spring is compressed until the solenoid contacts meet the solenoid terminals. The starting motor activates. This causes the pinion gear to turn until the pinion gear meshes with the ring gear. The ring gear allows the engine to turn.
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| Illustration 7 | g00583777 |
Solenoid Switch (13) Solenoid (17) Solenoid contacts (18) Hold-in coil (19) Pull-in coil (20) Return spring (21) Plunger | |
The solenoid (13) contains the following items:
- Solenoid contacts (17)
- Hold-in coil (18)
- Pull-in coil (19)
- Return spring (20)
- Plunger (21)
When the key start switch is closed, the pull-in coil (19) and the hold-in coil (18) are energized. The energized coils will move the plunger (21). The plunger movement allows the pinion to move. When solenoid contacts (17) close, full battery current is sent to the motor and the engine begins to crank. When the engine starts, the overrunning clutch protects the armature from excessive speed until the key start switch is released. After the switch is released, the return spring (20) moves in order to disengage the pinion.