Chapter 1 The Automobile 21
Accessory and Safety Systems
Common accessory systems include the air condi-
tioner, sound system, power seats, power windows,
and rear window defogger. Common safety systems
include seat belts, air bags, and security systems. See
Figures 1-24 and 1-25.
Hybrid Vehicles
A hybrid electric vehicle (HEV) uses two methods
of propulsion: an internal combustion engine and an
electric drive train in tandem. All major auto manu-
facturers now build and sell hybrid vehicles.
Hybrid cars use at least one integral electric motor-
generator assembly for propulsion. The four funda-
mental parts of a basic hybrid drive train include:
• Motor-generator—A motor-generator acts as
both a high-torque, electric drive motor and
as a powerful generator of electricity in hybrid
vehicles.
When acting as a motor, the motor-generator
can produce tremendous torque and power
to fully propel the vehicle. When serving as a
generator, the motor-generator produces high
electrical current for recharging the HV battery.
• HV (high-voltage) power cables—HV power
cables are large-diameter, insulated conduc-
tors that carry huge amounts of electricity to
and from the components of the electric drive
train. Since they carry very dangerous levels of
electrical energy, orange insulation denotes HV
power cables on all hybrid vehicles.
• HV battery—The HV battery contains a large
number of battery cells wired in series for stor-
ing and discharging high amounts of energy.
Two HV power cables often connect the HV
battery to the HV power control module in a
hybrid. Three more HV power cables connect
the HV power control module to the motor-
generator for electric propulsion or HV battery
recharging.
• HV power control module—An HV power con-
trol module is a set of high-power circuits that
manage the fl ow of electrical energy through
a vehicle’s electric drive train. It can send bat-
tery power to the motor-generator for vehicle
propulsion. The HV power control module
cause a car to skid off the road in a high-speed turn
or to skid out of control during high-speed braking.
Suspension System
The suspension system allows the vehicle’s wheels
and tires to move up and down with little effect on
body movement. This makes the vehicle’s ride smooth
and safe. The suspension system also prevents exces-
sive body lean when turning corners quickly. As you
can see in Figure 1-22, various springs, bars, swivel
joints, and arms make up the suspension system.
Steering System
The steering system allows the driver to control
vehicle direction by turning the wheels right or left.
It uses a series of gears, swivel joints, and rods to do
this. Study the names of the parts in Figure 1-22.
Brake System
The brake system produces friction to slow or
stop the vehicle. When the driver presses the brake
pedal, fl uid pressure actuates a brake mechanism at
each wheel. These mechanisms force friction mate-
rial (brake pads or shoes) against metal discs or
drums to slow wheel rotation. Figure 1-23 shows the
fundamental parts of a brake system.
Differential
assembly
Power
output to
drive axle
Shift rod
assembly
Housing or
case
Transmission
assembly
Figure 1-21. A transaxle contains a transmission and a
differential in one housing. (Ford)