62668724c2f9bSTARTING SYSTEM final ppt.pdf

Department of Automobile
Starting System Fundamentals

Objectives
• Explain electric motor principles
• Describe starter parts
• Understand the operation of a solenoid
• Discuss starter drive operation

Introduction
• Starter system
– Important part of the automotive electrical
system
• Without a starter
– Car would have to be push started
• Henry Ford's Model T had a hand crank for the engine

Location of starting motor

STARTING MOTOR

Starter Motor
• Starter circuit includes:
– Starter motor
– Starter drive
– Battery
– Ignition switch
– Solenoid
• Starter operates at a high rpm
– Has a small pinion gear on end of starter drive
• Meshes with a large gear on the flywheel

Starter Motor (cont'd.)
• Gear ratio
– Provides starter with leverage needed
– Gear ratio between the two gears is about 18:1
• Crank engine at normal cranking speed
– Starter motor must be turned 3,600 rpm

STARTING SYSTEM

STARTING
Battery provides the current to turn
the starter motor.
Fuse protects the circuit.
Ignition switch closes the circuit.
SYSTEM
Relay uses small amount of current to control large amount.
Neutral safety switch opens the circuit until the vehicle is in neutral
(manual transmission), or park (Automatic). (Can be adjusted)
Solenoid does the same thing as relay, but performs
mechanical operation. It is an electromagnetic switch.
Starter motor engages pinion gear to ring gear (mounted on flywheel,
Or torque converter).

Starter Motor Fundamentals
• Starters use electromagnetism to convert
electrical energy to mechanical power
• Two separate magnetic fields
– Produced by horseshoe
– Resulting from current flowing through the
conductor
• Push-pull effect on armature
– Causes conductor to move from stronger to
weaker magnetic field

Starter Motor Fundamentals (cont'd.)
• Conductor is formed into a loop
– Loop wire is placed between two electromagnetic
pole shoes
• Ends of the wires have commutator bars
– Multiple loops make up an armature
• Armature has a soft iron core
– Field coils made of heavy copper ribbons
• Wound around soft iron cores called pole shoes

Starter Motor Fundamentals (cont'd.)
• Some starter motors don't have field coils
– Have permanent magnets instead
• Simpler
• Weigh less
• Create less heat
• Brushes, usually made of carbon, are lightly
held against the commutator by springs
– Usually four brushes, which are together in pairs

Starter Electrical Circuit
• Starter motor requires a large amount of
current
– Battery must be in good enough condition to
provide sufficient current
– Starter switched on by ignition switch and key
• Most cars use a solenoid
– Engages starter drive pinion with flywheel ring
gear
• When a coil in the solenoid is energized, a magnetic
field draws the piston into the coil

STARTING SYSTEM
•Starting system uses battery power and an electric DC
engine crankshaft for engine starting.
motor to turn
•Changes electrical energy to mechanical.
•Provides gear reduction/torque multiplication (16:1 to 20:1).
•When the ignition key is turned on the current flows through the
solenoid coil. This closes the contacts, connecting battery to the
starter motor.

STARTING
Inside the starter motor.
SYSTEM
1.
2.
3.
4.
5.
Starter
Starter
Starter
Starter
Starter
solenoid
drive/bendix
armature
brushes
bearings

STARTING SYSTEM
COMMUTATOR sliding electrical
windings and the brushes.
•Insulated from each other.
connection between the motor
•Several loops of wire and a
commutator with many segments
are used to increase motor power
and smoothness.

STARTING SYSTEM
BRUSHES ride on top of the commutator to carry battery current
to spinning windings.
•Replaced during starter rebuilding.

STARTING SYSTEM
StarterArmature consists of the armature shaft, armature core,
commutator and armature windings.
•Armature must produce high torque and high speeds.

STARTING SYSTEM
Field winding is a stationary insulated wire wrapped in a circular
shape. It creates a strong magnetic field around the motor armature.

Starter Drives
• Have an overrunning, or one-way clutch
– Transmits motion from starter to flywheel
– Disengages from the engine at startup
– Teeth on the starter drive gear are tapered

STARTING SYSTEM
Pinion Gear is attached to the starter drive and when starting the
vehicle the pinion gear engages with flywheel or
ring gear. It is moved by the YOKE.

STARTING SYSTEM
Overrunning Clutch Starter
•Locks it in one direction and unlocks it in another.
•It allows the pinion gear to run free when engine begins to run.

STARTING SYSTEM
•Has an extra gear on the armature to further increase the rotating force
•Gear ratio between flywheel and armature is 45:1
•Hence, the armature turns 45 times to turn the flywheel (engine) once.
•This provides high cranking torque for starting.
Gear Reduction Starter

Wiring diagram of Starting system

Starter Electrical Circuit (cont'd.)
• Ignition switch: opens and closes the circuit to
the starter
– Electricity can take two paths in the starter
• Safety switches
– Circuit on newer cars with automatic
transmissions has a neutral safety switch
– Late-model vehicles with manual transmissions
have a starter/clutch interlock switch

STARTING SYSTEM
DC electric motors have three common types of internal connections:
Series-wound motors develop maximum torque at initial start-up.
Torque decreases as motor speed increases.
Shunt-wound motors have less starting torque but more constant
torque at varying speeds.
Compound-wound motors have both series and shunt windings.
They have good starting power with fairly consistent operating speeds.

STARTING SYSTEM
Starting Solenoid
•Is a high current relay (controlled by
low current)
•Works as an electromagnet switch
•If faulty it will simply make a
clicking sound when one is attempting
to start the vehicle.

STARTING SYSTEM
Neutral safety switch prevents the vehicle from starting while in
gear. (can be adjusted)
Clutch Safety Switch prevents the vehicle from starting, unless the
clutch pedal is pressed. (adjustable)

STARTING SYSTEM
When replacing a starter motor, make sure
the spacer shims are of correct thickness
are installed.
•Shims sit in between the starter
housing and the engine block.
If these shims are left out, the pinion
gear may not mesh with the
flywheel gear properly, and might
cause damage to the ring-gear.
•Starter metallic grinding
sound.

STARTING SYSTEM
QUICK TESTING
No crank with no headlights
•Dead Battery(corroded terminals)
or an open in electrical circuit.
•Burned fuse.
•Burned or broken wire.

STARTING SYSTEM
QUICK TESTING
Head lights go out when cranking
•Indicates heavy current draw.
•Battery may be weak.
•Starter motor may be shorted.

STARTING SYSTEM
QUICK TESTING
Lights stay bright but, no crank
•High resistance or an open in starting circuit.
•Possibly Ignition switch
•Wiring , solenoid, cable connections, relay, fuse.

STARTING SYSTEM
Current Draw Test most of the starters draw over 200Amps.
•Hookup the V
A
T
•Disconnect Fuel/ignition
•Crank engine for 5-10 seconds and note the voltage.
•Load the battery until same voltage is obtained
and record theAmp.
•TheAmps will equal the current
the starting motor.
drawn by
4
6
8
Cylinder
Cylinder
Cylinder
–
–
–
150/200
175/250
225/300
amps
amps
amps

STARTING SYSTEM
Voltage Drop Test checks for high resistance across a cable/connection
•Disable ignition/fuel
•Hook voltmeter between +ve battery post and +ve starter terminal
•Hook voltmeter between -ve battery post and starter ground.
•Crank the engine (5-10Sec.), V
oltmeter should not read more
then 1volts.
If greater:
•Loose electrical connections.
•Burned or pitted solenoid contacts.

62668724c2f9bSTARTING SYSTEM final ppt.pdf

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