by Russell Krick Publisher The GoodheartWillcox Co Inc
by Russell Krick Publisher The Goodheart-Willcox Co. , Inc. Tinley Park, Illinois © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
© Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
q Starting system principles q Starting motor construction © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
The starting system uses battery power and an electric motor to turn the engine crankshaft for engine starting © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Basic Starting System q The ignition switch energizes the solenoid, which allows the battery to energize the starting motor, which turns the flywheel gear, starting the engine © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Components q Battery m source of energy q Ignition switch m allows the driver to control operation q Solenoid m high current relay (switch) q Starting motor m high-torque electric motor © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Energizing the Starting System q Turning the ignition key to the “start” position allows current to flow through the solenoid coil q Magnetism closes the solenoid contacts, connecting the battery to the starting motor q The motor turns the flywheel ring gear until the engine runs on its own © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
De-energizing the Starting System q When the ignition key is released to the “run” position, no current flows to the solenoid coil q The solenoid contacts open, the starter stops turning, and the starter gear moves away from the flywheel © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Starting Motor Fundamentals q Converts electrical energy from the battery to mechanical energy to crank the engine q Like other electric motors, the starting motor produces a turning force through the interaction of magnetic fields inside the motor assembly © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Magnetic Field Action q Made up of invisible lines of force q Since like charges (fields) repel each other and unlike charges (fields) attract each other, magnetic fields can be used to produce motion © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Magnetic Field Action © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Simple Electric Motor If a current-carrying winding is placed inside a magnetic field, the winding rotates away from the pole shoes © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Commutator and Brushes q Keep a motor turning by controlling the current through the windings q The commutator serves as a sliding connection between the motor windings and the brushes q The brushes ride on top of the commutator, carrying current to the spinning winding © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Commutator and Brushes The commutator reverses the electrical connection when the loop rotates around © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Increasing Motor Power q Several windings (loops of wire) and a commutator with many segments are used to increase motor power q As the motor spins, many windings contribute to the motion, producing a smooth turning force © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Armature q Supports the windings q Increases the strength of each winding’s magnetic field © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Field Windings q Stationary insulated wire wrapped in a circular shape q When current flows through the field windings, the magnetic field between the pole shoes becomes very large q This field acts against the armature’s field, producing motion © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Armature and Field Windings © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Starter Pinion Gear q Small gear on the armature shaft q Engages a large ring gear on the engine flywheel q Moves into and meshes with the flywheel ring gear © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Starter Pinion Gear © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Overrunning Clutch q Locks in one direction q Releases in the other direction q Allows the pinion gear to turn the flywheel ring gear for starting q Lets the pinion gear freewheel when the engine starts © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Overrunning Clutch Locks the flange to the pinion gear in one direction and releases in the other direction © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Overrunning Clutch Operation Rollers jam and lock in one direction and release in the other direction © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Pinion Gear Assembly Pinion gear assembly slides on the shaft for engagement © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Starter Solenoid q An electromagnetic switch q Makes an electrical connection between the battery and the starting motor q Allows the low current ignition switch circuit to control the high current starting motor © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Starter Solenoid Plunger movement pulls the disc into contact with the battery terminal and the starter terminal to activate the starter motor © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Solenoid Operation q Low current flows through the windings when the ignition is in the start position q The magnetic field pulls the solenoid plunger and disc toward the windings q The disc touches both of the highcurrent terminals q High current flows to the starter motor © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Solenoid Operation © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Solenoid Functions q Closes the battery-to-starter circuit q Pushes the starter pinion gear into mesh with the flywheel ring gear q Bypasses the resistance wire in the ignition circuit © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
All starting motor construction is similar, but there are slight variations in design © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Main Parts of a Starting Motor q Armature m windings, core, shaft, and commutator assembly that spins inside a stationary field q Pinion drive assembly m pinion gear, overrunning clutch, and sometimes a shift lever and solenoid q Commutator end frame m end housing for brushes, brush springs, and shaft bushing © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Main Parts of a Starting Motor q Field frame m center housing that holds field coils and pole shoes q Drive end frame m end housing around pinion gear; has bushing for armature shaft © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Starting Motor Types q Classified by type of pinion gear engagement q There are two main types: m movable pole shoe starting motor m starter-mounted solenoid (starting motor with solenoid) © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Movable Pole Shoe Starting Motor Uses a drive yoke lever to move the pinion gear into contact with the flywheel gear © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Movable Pole Shoe Starting Motor A magnetic field pulls the pole shoe downward, forcing gear engagement as the armature starts to spin © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Starter-Mounted Solenoid plunger moves a lever to engage the pinion gear © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Starter-Mounted Solenoid The solenoid not only operates the pinion gear but also completes the battery-to-starter circuit © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Solenoid Operation © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Permanent-Magnet Starter Uses special high-strength magnets in place of conventional field windings © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Starting Motor Torque q A starting motor must produce high torque q Difference in gear size between the small pinion and large flywheel ring gear increases turning force © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Reduction Starter Extra gears further increase torque © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Internal Motor Circuits q Series-wound motor q Shunt-wound motor q Compound-wound motor © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Series-Wound Motor Develops maximum torque at initial start-up and decreases as motor speed increases © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Shunt-Wound Motor Produces less starting torque but more constant torque at varying speeds © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Compound-Wound Motor Has both series and shunt windings and produces good starting power and constant operating speed © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Neutral Safety Switch q Prevents the engine from cranking unless the shift selector is in neutral or park q Mounted on the shift lever or on the transmission © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Neutral Safety Switch Wired in series with the starter solenoid © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Starter Relay q Opens or closes one circuit by responding to an electrical signal from another circuit q Uses a small current from the ignition switch to control a larger current through the starter solenoid q Reduces the load on the ignition switch © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Starter Relay Operation q Ignition switch is turned to “start” q Current flows through the relay windings q Magnetism closes the relay contacts q Contacts complete the circuit to the solenoid windings q Solenoid contacts close, which energizes the starting motor © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Starting System Circuit © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
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