car parts starter motor

car parts starter motor

Blog Article

Key Components of a Car Starter Motor

1. Armature
   The rotating core of the starter motor, composed of a laminated iron core with copper wire windings. When an electric current flows through the windings, it generates a magnetic field that interacts with the field magnets, producing rotational motion.
2. Field Windings or Permanent Magnets
   • Field Windings: Coils surrounding the armature that create a magnetic field when energized, interacting with the armature to drive rotation.
   • Permanent Magnets: Found in modern, compact starters (e.g., in small cars or motorcycles), these eliminate the need for field windings, offering higher efficiency and a smaller footprint.
3. Commutator
   A segmented copper cylinder attached to the armature shaft. It reverses the current direction in the armature windings as it rotates, ensuring the magnetic field remains consistent and the armature spins in one direction.
4. Brushes
   Made of conductive graphite or carbon, these components press against the commutator via springs, transferring electrical current from the battery to the armature. Brushes wear over time and may require replacement to maintain starter function.
5. Solenoid
   An electromagnetic switch mounted on the starter motor. When activated by the ignition key, it:
   • Connects the battery to the starter motor via high - current contacts.
   • Pushes the pinion gear forward to engage with the engine’s flywheel ring gear.
6. Pinion Gear
   A small gear attached to the starter shaft, designed to mesh with the flywheel’s ring gear. It transfers the starter’s rotational force to the engine, cranking it to start. Once the engine runs, the pinion disengages automatically to prevent over - speeding.
7. Overrunning Clutch
   Also known as a “drive gear clutch,” this mechanism connects the pinion gear to the armature shaft. It allows the pinion to drive the flywheel during starting but slips when the engine speed exceeds the starter’s speed, protecting the starter from damage.
8. Starter Relay
   A low - current switch that controls the high - current flow to the starter motor. Activated by the ignition switch, it prevents the ignition circuit from handling the starter’s high amperage directly.
9. Lever Fork (Shift Lever)
   A mechanical linkage that translates the solenoid’s linear motion into the pinion gear’s engagement with the flywheel. It ensures the pinion meshes correctly before the starter motor powers on.
10. Solenoid Plunger
    A cylindrical rod inside the solenoid that moves when the solenoid is energized, pushing the lever fork to engage the pinion gear. It acts as a mechanical connector between the solenoid and the drive mechanism.
11. Housing and End Caps
    The metal casing that encloses and protects the starter’s internal components, with end caps securing the armature shaft and brush assembly.