introduction of starting system

1. Introduction
 The starting system is a combination of mechanical and electrical parts that work
together to start engine
 The starting system is designed to convert electrical energy from battery into
mechanical energy in the starring motor
 The engine can’t “start” rotational movement on its own. It needs an electric motor
to get it up to a minimal RPM to run, then the engine can run under its own power.
The starter is the biggest load on the vehicles electrical system.
 Before electric starters, automobile owners needed to crank the engine over
themselves! This was not ideal for any kind of quick getaway.
 The starter motor is an electric motor that rotates your engine in order to allow the spark and fuel injection systems to begin the
engine's operation under its own power. Typically, the starter is a large electric motor and stator coil mounted to the bottom
(generally to one side) of the vehicle's transmission bell housing where it connects to the engine itself. The starter has gears which
mesh with a large flywheel gear on the backside of the engine, which turns the central crankshaft.
 Because this is a lot of physical weight and friction to overcome, starter motors are generally powerful, high-speed motors

2. Battery
The automotive battery, also known as a lead-acid storage battery, is an
electrochemical device that produces voltage and delivers current. In an
automotive battery, we can reverse the electrochemical action, thereby
recharging the battery, which will then give us many years of service.
The purpose of the battery is:
 To supply current to the starter motor, provide current to the ignition
system while cranking,
• To supply additional current when the demand is higher than the
alternator can supply and to act as an electrical reservoir.
Components of starting system

3. Ignition Switch
The ignition switch allows the driver to distribute electrical current to where it is needed. There are
generally 5 key switch positions that are used:
1. Lock- All circuits are open ( no current supplied) and the steering wheel is in the lock position. In
some cars, the transmission lever cannot be moved in this position. If the steering wheel is
applying pressure to the locking mechanism, the key might be hard to turn. If you do experience
this type of condition, try moving the steering wheel to remove the pressure as you turn the key.
2. Off- All circuits are open, but the steering wheel can be turned and the key cannot be extracted.
3. Run- All circuits, except the starter circuit, are closed (current is allowed to pass through). Current
is supplied to all but the starter circuit.
4. Start- Power is supplied to the ignition circuit and the starter motor only. That is why the radio
stops playing in the start position. This position of the ignition switch is spring-loaded so that the
starter is not engaged while the engine is running. This position is used momentarily, just to
activate the starter.
5. Accessory- Power is supplied to all but the ignition and starter circuit. This allows you to play the
radio, work the power windows, etc. while the engine is not running.
Most ignition switches are mounted on the steering column. Some switches are actually two separate
parts;* The lock into which you insert the key. This component also contains the mechanism to lock the
steering wheel and shifter.

4. Neutral Safety Switch
This switch opens (denies current to) the starter circuit when the
transmission is in any gear but Neutral or Park on automatic transmissions.
This switch is normally connected to the transmission linkage or directly
on the transmission. Most cars utilize this same switch to apply current to
the backup lights when the transmission is put in reverse. Standard
transmission cars will connect this switch to the clutch pedal so that the
starter will not engage unless the clutch pedal is depressed. If you find that
you have to move the shifter away from park or neutral to get the car to
start, it usually means that this switch needs adjustment. If your car has an
automatic parking brake release, the neutral safety switch will control that
function also.

5. Starter Relay
A relay is a device that allows a small amount of electrical current to
control a large amount of current. An automobile starter uses a large
amount of current (250+ amps) to start an engine. If we were to allow
that much current to go through the ignition switch, we would not only
need a very large switch, but all the wires would have to be the size of
battery cables (not very practical).
A starter relay is installed in series between the battery and the starter.
Some cars use a starter solenoid to accomplish the same purpose of
allowing a small amount of current from the ignition switch to control
a high current flow from the battery to the starter. The starter solenoid
in some cases also mechanically engages the starter gear with the
engine

6. Battery Cable


7. Starter Motor
The starter motor is a powerful electric motor, with a small gear (pinion)
attached to the end. When activated, the gear has meshed with a larger
gear (ring), which is attached to the engine. The starter motor then spins
the engine over so that the piston can draw in a fuel/ air mixture, which is
then ignited to start the engine. When the engine starts to spin faster than
the starter, a device called an overrunning clutch (Bendix drive)
automatically disengages the starter gear from the engine gear.
Starter Motor Parts are:
 Starter Solenoid
 Starter Motor
 Starter Drive Pinion

8. Starter solenoid
the starter solenoid sits on top of the starter motor and performs two main functions
 acts as a heavy-duty relay for the starter
 engages the starter pinion gear to the ring gear on the flywheel/flex-plate/torque converter.
The solenoid has 3 terminals; a B+ terminal, an S terminal, and an M terminal. The B+ terminal is
connected directly to the battery positive at all times. This wire is infused meaning that if there is a
short to ground on this wire, there will be sparks until the battery is drained. The wire from the battery
to the B+ terminal will be very thick because it needs to carry call the current necessary to turn the
starter motor and overcome engine compression. The S terminal receives power from the ignition
switch either directly or indirectly with a relay. The S terminal connects to two winding, the pull-in
winding and the hold in the winding. These winding are simply coils of wire wrapped around a plunger,
which when energized produce and electromagnet. The pull-in winding is made up of thicker winding
and creates a strong electromagnet. It is grounded through the M terminal and starter motor. The hold-
in winding is smaller and creates a weaker electromagnet. It is grounded directly to the starter case.
The plunger sits in the middle of the winding and is held in place by a spring. The plunger gets
pulled/held in by the winding when they are energized. At one end it is connected to a lever which
forces the starter pinion gear to mesh with the ring gear. At the other end, when the plunger reaches the
end of its travel, it pushes a contact disk which connects the B+ terminal to the M terminal which is
connected to the starter motor. This energizes the starter motor and also causes the pull-in winding to
stop flowing power. This is because once the contact disk connects B+ to M there is 12v on both sides

9. Starter solnoid

10. Starter Pinion Drive
The starter drive pinion is held out mesh with the ring gear by a spring until the
starter solenoid engages and moves the lever, pushing the starter pinion into
mesh with the ring gear. When the engine starts, the operator allows the key to
return to the run position. This cuts power to the starter solenoid, which allows
the spring to push the plunger back to its normal position. The plungers lever
will pull the starter drive pinion back, out of mesh with the ring gear.
It is important that the starter drives the flywheel and not the other way around.
This is why starter drives have a one-way clutch. The one-way clutch allows
the starter to turn the flywheel, but if the flywheel starts to cause the starter
pinion to turn faster than the armature, the one-way clutch will slip. This
protects the starter from spinning too fast.

11. Working Principles

12. Starter solnoid

13. Starter solnoid

15. Thank you