Automotive Combined Set

As in every other vehicle system:

Computer control is being incorporated into the brake system

Most cars now come equipped with Antilock brakes(ABS) which:

Prevent wheel lock under hard braking conditions

The ABS system uses speed sensors attached to each wheel to:

Tell a computer(the ABS computer) relative speeds of each well

If the ABS computer detects a difference in wheel speed more than a preset amount:

The computer uses pumps and valves in the ABS system to adjust the brake pressure for affected wheel or wheels

This gives more control to the drive in:

Slippery conditions and allows the vehicle to stop more predictably and safely

Braking pressure is usually boosted using:

A brake booster

The brake booster is located:

Between the brake pedal and the master cylinder

Why is engine intake manifold vacuum utilized to generate greater force on the master cylinder?

So higher hydraulic pressures can be generated in the brake system for the same amount of pedal force provided by the driver

Some brake booster systems use fluid pressure from:

The power steering system to increase braking power

Why are disc brakes much more powerful than drum brakes?

Because of disc brakes’ superior ability to reject heat energy

The pistons used to actuate disc brakes are much larger and:

Can apply more force to brake pads

Also, brake rotors used in disc brakes are more easily cooled:

As they are better exposed to the cool air under the car and are often designed with air passages through them to enhance heat rejection

The piston that operates a disc brake is house in:

A Brake Caliper

The caliper “floats” laterally as the brake is applied and released and:

Makes it possible for one piston to operate the pads on both side of the rotor

This makes the caliper operate similar to:

A C-clamp

As the screw is tightened on one side:

The entire assembly is drawn together and pinches tightly on the item being clamped; in this case, the brake rotor

The parts that develop the friction in a drum brake are:

Brake shoes

In any drum brake assembly, there are:

Two brake shoes

As hydraulic pressure is applied to the wheel cylinder, which is located between the brake shoes:

The pistons inside it push apart and act against them

The brake shoes then push outward against the inner surface of the brake drum:

And the resulting friction between the brake shoes and brake drum slows the vehicle

What are one of the most critical components of the suspension and steering system?

Tires

What do tires support?

The weight of the vehicle and make final contact with the road surface

The most common tire design is:

Radial

What is the radial tire known for?

It’s stable footprint and low rolling resistance

Tire construction begins with:

Beads

The bead is:

A circular piece of high strength material like steel wire that is encased in rubber

The bead forms:

The mounting point for the tire on the rim

Body plies form:

The main body of the tire and run from bead to bead

All other parts of the tire attach to the body plies, including:

The liner(sealed inside the tire), the sidewalls, and the tread

Why are Belts used between the plies and the tread?

To help stabilize the tire’s footprint(where the tire makes contact with the road)

A stable footprint means:

Better traction under all road conditions, and makes the vehicle handle and brake better

The primary maintenance that should be performed on suspension and steering systems is:

Lubrication of the ball joints, tie rod ends, and other components

What should the maintenance be done with?

A hand powered grease gun, and the amount of grease should be metered carefully

The most important part of tire maintenance is:

Proper Inflation

Low inflation pressures:

Can be very dangerous as well as increase of the rolling resistance of the vehicle, thereby increasing fuel consumption

An underinflated tire can:

Seriously damage the tire, which could lead to a blow out and accident

Too much tire pressure, or overinflation:

Can lead to excessive tire wear

An extremely over inflated tire can also lead to:

A possible blow out and accident

Automotive manufacturers label each vehicle with the:

Recommended inflation pressures for the front and rear tires

Brake Pedal:

The mechanical connection between the driver’s foot and master cylinder

Master Cylinder:

Located in the engine compartment in front of the driver, the ________ generates the fluid pressure to operate the brake assemblies at the wheels

Fluid Reservoir:

Provides fluid to the brake circuits. The _____________ is located on top of the master cylinder

Brake Lines:

Transmit fluid pressure from the master cylinder to the brake assemblies. These can be steel lines that run along the vehicle chassis or flex hoses that are used to connect the steel lines to the brake assemblies

Brakes work by:

Converting the energy of the vehicle’s motion into heat energy through friction

Drum Brake:

Expanding shoes make contact with a rotating drum to create friction

Disc Brake:

Brake pads one either side of a rotating disc are “pinched” together to slow the vehicle

Brake Systems are:

Hydraulically operated

A pumping piston, located in the master cylinder:

Is operated by the brake pedal and puts pressure on the system’s brake fluid

Since fluids cannot be compressed:

The brake fluid travels through the brake lines and moves the pistons in the brake assemblies to operate the brakes

The harder the driver presses on the brake pedal:

The more fluid pressure is developed and more braking power is generated

In order to make a vehicle ride smoothly:

The wheels must be able to move up and down while the vehicle chassis stays steady

This is the job of the vehicle springs:

They must be able to allow this movement of wheels without transmitting road shock

However, the springs absorb energy as this happens and must:

Release this energy without bouncing the vehicle after encountering a bump

The shock absorber is installed between the chassis and control arm to:

Help dissipate or absorb the energy stored in the spring as it either compressed(or jounced) or extended(or rebounded).

Without properly functioning shock absorbers:

The vehicle will continue to bounce up and down after the vehicle has hit a bump in the road

The shock absorber uses a piston and hydraulic oil to:

Absorb the excess of mechanical energy from the suspension system and then releases that same energy in the form of heat

The upper and lower control arms:

form the supports for the steering knuckle

The control arms are attached to the chassis through:

The use of control arm bushings

The spring is placed between:

The chassis and one of the control arms

The spring can be installed on either:

The upper or lower control arm in a long short arm suspension

The control arm with the spring on it becomes:

The load bearing arm as the vehicle weight is supported through it on the way to the steering knuckle and tire assembly

An upper ball joint and lower ball joint are used to:

Attach the steering knuckle to the control arms

Ball joints are built similar to a human hip joint:

With a ball and stud rotating in a socket to allow a wide arc of movement

As the control arms move up and down:

The ball joints allow the steering knuckle to move freely with them

The ball joints also allow:

The steering knuckle to turn left and right as it is moved by the steering linkage

The steering linkage forms:

The connection between the steering wheel and steering knuckle

There are two main designs in common use?

The Linkage steering and rack and pinion

Long short arm suspensions most commonly use Linkage Steering to:

Connect the steering column to the pitman arm, center link, and idler arm

Tie rods are then used to make:

The final connection to the steering knuckles

Why do smaller vehicles most commonly use the rack and pinion steering system?

Because it is the most compact of the two major steering systems

Springs:

Hold the vehicle’s chassis up and allow wheels to move up and down in relation to it

Shock Absorber:

Absorb the energy released by the up and down movement of the vehicle wheels

Control Arms(A arms):

The long short arm suspension system uses a upper and lower ___________ to maintain the vertical orientation of the steering knuckle as the wheel moves up and down

Steering Knuckle:

Connects to the upper and lower control arms through the use of ball joints. The wheel hub mounts on the spindle, which is part of the _________

Ball joints:

Ball and socket assemblies that allow the steering knuckle to turn and move up and down simultaneously

Steering Linkage:

Connects the steering wheel to the steering knuckle

Wheel hub:

Forms the mounting point for the vehicle’s tire assembly

Tire:

Makes contact with the road and provides a “footprint” to aid in vehicle stability and handling

Automatic Transmissions:

Are much more complex than their manual counterparts, yet are much easier to operate

The reason why many drivers prefer them is:

That automatic transmissions do not use a driver operated clutch

Instead of using a clutch, automatics transmit engine torque from the engine to the transmission through:

A torque converter

The Torque converter uses fluid to:

Transmit power, and allows for a certain amount of slippage when the vehicle is stopped

How do automatic transmissions do all of the gear selections for the driver?

In the transmission using hydraulic pressure to select the proper planetary sets

Virtually all modern automatic transmissions are:

Controlled electronically by the vehicle’s powertrain control module

Another modern automatic transmission is:

The continuously variable transmission(CVT)

A CVT transmission does:

Not utilize specific gear sets to determine the transmission ratio(or gears)

Instead, CVT relies on two opposing sets of cones:

One for input and one for output with a chain or belt running in between

The effective ratio of the transmission depends on:

Where the chain(or belt) is riding on the two cones

Why can the ratio be varied continuously between the limits of the diameters of the two cones?

Because the transmission’s effective ratio is not limited to specific gears as in a typical transmission

Transmissions are built with:

Several forward ratios that are based on the specific gears that are used

Typically transmissions are therefore said to have:

Speeds or Gears

For instance, a four speed transmission would have:

Four forward gear ratios and one reverse ratio

A driver would typically start from a stop using:

Low(first) gear

In this gear, the transmission would increase:

The torque from the engine sufficiently to be able to start the vehicle from a standstill

Low gear would limit the vehicle’s speed once it started rolling so:

The driver would then select second gear and so on as the vehicle continued on to accelerate

High(fourth) gear would be used to allow:

The vehicle to cruise on the highway

Engine speed would be moderate to:

Low in this gear, allowing for maximum fuel economy and quiet running

To accelerate quickly, however:

The driver would downshift to a lower gear in order to increase engine speed and power

Proper gear selection is important when:

Operating with a manual transmission

Modern transmissions now have:

As many as eight forwarded speeds