MCTI - Auto Tech, Chapter 1 Terms

assembly

A set of fitted parts designed to complete a function.

body

A steel, aluminum, fiberglass, plastic, or composite skin forming the outside of the vehicle. This is painted to give the vehicle an attractive appearance.

automobile

A term derived from the Greek work 'autos', which means self, and the French word mobile, which means moving.

component

A term used when referring to an electrical or electronic part.

cylinder

A round hole bored (machined) in the block. It guides the piston movement.

sedan

A car that has front and back seats and will carry four to six people. It has center body pillars, or 'B' pillars, between the front and rear doors. Available with two- or four- doors.

cycle

A complete series of events.

piston

A cylindrical component that transfers the energy of combustion (burning of air-fuel mixture) to the connecting rod.

system

A group of related parts and assemblies that performs a specific function (job or task).

block

A metal casting that holds all the other engine parts in place.

drive shaft

Also known as a propeller shaft. This transfers power from the transmission to the rear axle assembly.

volatile

Burnable. Evaporates easily.

safety systems

Common types of these systems include seat belts, air bags, and security systems.

regenerative braking

During braking, the rotational force of the vehicle's drive axles spins the motor-generator's armature, causing the motor-generator to produce electrical energy to recharge the battery.

fuel injectors

Fuel valves.

internal combustion engine

Gasoline or diesel engine that propels the vehicle at cruising speed and drives the motor-generator.

hatchback or liftback

Has a large read door for easy access when hauling items. Available in three- or five- door models.

station wagon

Has a long, straight roof that extends to the rear of the vehicle. These have large rear interior compartments and come in two- or four-door models. Some have space for up to nine passengers.

convertible

Has a vinyl or cloth top that can be raised and lowered. Has no door pillars, and its strength is designed into the frame or floor pan. Most have two-doors, some have four.

hybrid control module

High power electrical electronic circuits that manage the flow of electrical energy through a vehicle's electrical-mechanical drive train.

body-over-frame construction

In this, the frame consists of thick steel members. The chassis parts and the body bolt to this frame. Also called full frame construction or perimeter frame construction, this design is heavy but strong. It is used on full-size cars, vans, pickup trucks, and sport-utility vehicles.

high-voltage cables

Large diameter, insulated conductors that carry voltage between the motor, generator, hybrid control module, and battery pack.

hybrid battery pack

Large set of battery cells that can store huge amounts of electrical energy and output high current and voltage to help propel the vehicle.

Sports-utility vehicles

Often equipped with four-wheel-drive systems and have a tall body design. They provide the comfort of a passenger car, the interior space of a station wagon, and the durability of a truck.

chassis

Often used when referring to a vehicle's frame and everything mounted to it except the body - tires, wheels, engine, transmission, drive axle assembly, and frame.

hardtop

Similar to a sedan, but it has no 'B' pillars. Available with two- or four- doors.

minivan

Similar to the station wagon, but it has a higher roofline for more headroom and cargo space. Most are designed to carry seven passengers.

technology

The application of math, science, physics, and other subjects.

torque converter

The input shaft of an automatic transmission is connected to the engine crankshaft through this instead of a clutch.

combustion.

The process by which fuel burns.

part

The smallest removable item on a car. A part is not usually disassembled.

frame

The strong metal structure that provides a mounting plate for the other parts of the vehicle. This holds the engine, transmission, suspension, and other assemblies in place.

multi-cylinder engines

These are engines typically used on automobiles. They have more than one piston and cylinder. Vehicles commonly have 4-, 6-, 8-, or 10-cylinder engines. Additional cylinders smooth engine operation and increase power output.

sensors

These are input devices that can produce or modify electrical signals with a change in a condition, such as motion, temperature, pressure, etc. These are the 'eyes, ears and nose' of the computer system.

actuators

These are output devices, such as small electric motors, that can move parts when energized by the control module. The actuators serve as 'hands and arms' of the computer system.

axles

These are steel shafts that connect the differential and drive wheels.

emissions control systems

These are used to reduce the amount of toxic (poisonous) substances produced by an engine. Some prevent fuel vapors from entering the atmosphere. Others remove unburned and partially burned fuel from the engine exhaust.

front drive axles

These connect the transaxle differential to the hubs and wheels of the vehicle. These axles are equipped with constant-velocity joints, which allow the front wheels to be turned to the left or right and to move up and down.

accessory system

These include the air conditioner, sound system, power seats, power windows, and read window defogger.

valve springs

These keep the valves closed when they do not need to be open.

valves

These open and close to control the flow of the air-fuel mixture into the combustion chamber and the exhaust gasses out of the combustion chamber.

lifters or followers

These ride on the camshaft and transfer motion to the other parts of the valve train.

rings

These seal the small gap around the sides of the piston. They keep combustion pressure and oil from leaking between the piston and the cylinder wall (cylinder surface).

rocker arms

These transfer camshaft action to the valves.

gasoline injection systems

These use a control module, sensors, and electrically operated fuel injectors (fuel valves) to meter fuel into the engine. This is the most common type of fuel system on gasoline, or spark ignition, engines.

radiator

This allows the coolant heat to transfer into the outside air.

manual transmission

This allows the driver to change ratios to better accommodate driving conditions.

steering system

This allows the driver to control the vehicle direction by turning the wheels right or left. It uses a series of gears, swivel joints, and rods to do this.

clutch

This allows the driver to engage or disengage the engine and manual transmission or transaxle.

suspension system

This 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.

crankshaft

This changes the reciprocating (up-and-down) motion of the piston and rod into useful rotary (spinning) motion.

electrical system

This consists of several subsystems (smaller circuits): ignition system, starting system, charging system, and lighting system. Each subsystem is designed to perform a specific function.

unibody construction

This consists of sheet body panels which are welded together to form the body and frame. Also called a 'space frame construction or unitized construction', this is the most common type of configuration used to build small and medium passenger cars. This construction reduces weight, improved fuel economy, and has a high strength-to-weight ratio. However, vehicles are not as strong as those with body-over-frame construction.

lighting system

This consists of the components that operate a vehicle's interior and exterior lights.

transaxle

This consists of transmission and a differential in a single housing. Although few rear-wheel-drive vehicles are equipped with these, they are most commonly used with front-wheel-drive vehicles. Both manual and automatic types are available.

rear axle assembly

This contains a differential and two axles.

throttle valve

This controls the airflow, engine speed, and engine power. When the throttle valve is open for more engine power output, the computer holds the injectors open longer, allowing more fuel to spray out. When the throttle valve is closed, the computer opens the injectors for only a short period of time, reducing power output.

thermostat

This controls the coolant flow and engine temperature.

camshaft

This controls the opening of the valves.

cylinder head

This covers and seals the top of the cylinder. It also holds the valves, rocker arms, and often, the camshaft.

automatic transmission

This does not need to be shifted by the driver. It uses an internal hydraulic system and, in most cases, electronic controls to shift gears.

engine fan

This draws cool air through the radiator.

intake stroke

This draws the air-fuel mixture into the engine's combustion chamber. The piston slides down while the intake valve is open and the exhaust valve is closed. this produces a vacuum (low-pressure area) in the cylinder. Atmospheric pressure (outside air pressure) can then force air and fuel into the combustion chamber.

water pump

This forces coolant through the inside of the engine, hoses, and radiator.

fuel pump

This forces fuel from the fuel tank to the engine.

alternator

This generator can produce electricity to recharge the battery and operate other electrical needs of the vehicle when the engine is running.

starting system

This has a powerful electric starting motor that rotates the engine crankshaft until the engine 'fires' and runs on its own power.

flywheel

This helps keep the crankshaft turning smoothly. It also provides a large gear for the starting motor.

control module

This is a computer (electronic circuit) that uses signals to from input devices (sensors) to control various output devices. The control module is the 'brain' of the computer system.

motor-generator

This is a device that can propel the vehicle like a motor or produce electrical energy like an alternator.

differential

This is a set of gears and shafts that transmits power from the drive shaft to the axles.

combustion chamber

This is a small cavity (hollow area) between the top of the piston and the bottom of the cylinder head. The burning or the air-fuel mixture occurs in the combustion chamber.

ignition system

This is needed on gasoline engines to ignite the air-fuel mixture. It produces an extremely high voltage surge, which operates the spark plugs. A very hot electric arc jumps across the tip of each spark plug at the correct time. This causes the air-fuel mixture to born, expand, and produce power.

charging system

This is needed to replace electrical energy drawn from the battery during the starting system operation. It forces electrical current back into the battery.

diesel fuel system

This is primarily a mechanical system that forces diesel fuel (not gasoline) directly into the combustion chambers. This does not use spark plugs to ignite the air-fuel mixture. It uses extremely high pressure produced during the compression stroke to heat the air in the combustion chamber. The air is squeezed until it is hot enough to ignite the fuel.

air-fuel ratio

This is the percentage of air and fuel.

four-stroke cycle

This is typically used within automobile engines. Four separate piston strokes are needed to produce one cycle. The piston must slide down, up, down, and up again to complete one cycle.

voltage regulator

This is usually built into the alternator and controls the voltage and current output of the alternator.

connecting rod

This links the piston to the crankshaft.

cooling system

This maintains a constant engine operating temperature. It removes excess combustion heat to prevent engine damage and also speeds engine warm-up.

fuel system

This must provide the correct mixture of air and fuel for efficient combustion (burning). This system must add the right amount of fuel entering the cylinders. This must alter the air-fuel ratio (percentage of air and fuel) with changes in the operating conditions (engine temperature, speed, load, and other variables).

compression stroke

This prepares the air-fuel mixture for combustion. With both valves closed, the piston slides upward and compression (squeezes) the trapped air-fuel mixture.

brake system

This produces friction to slow or stop the vehicle.

spark plug

This produces the electric spark for igniting the mixture of gasoline and air.

power stroke

This produces the energy to operate the engine. With both valves still closed, the spark plug arcs (sparks) and ignites the compressed air-fuel mixture. The burning fuel expands and develops pressure in the combustion chamber and on the top of the piston. This pushes the piston down with enough force to keep the crankshaft spinning until the next power stroke.

battery

This provides the electricity for the starting system.

engine

This provides the energy to propel (move) the vehicle and operate the other systems. Most consume gasoline or diesel fuel.

oil pump

This pulls oil out of the pan and pushes it to various moving parts of the engine.

exhaust system

This quiets the noise produced during engine operation and routes engine exhaust gases to the rear of the vehicle body.

lubrication system

This reduces friction and wear between internal engine parts by circulating filtered engine oil to high-friction points in the engine. It also helps cool the engine by carrying heat away from internal engine parts.

exhaust stroke

This removes the burned gasses from the combustion chamber. During this stroke, the piston slides up while the exhaust valve is open and the intake valve is closed. The burned fuel mixture is pushed out of the engine and into the exhaust system.

starting motor

This rotates the engine crankshaft until the engine 'fires' and runs on its own power.

drive belt

This spins the alternator pulley when the engine is running.

carburetor fuel system

This system uses engine vacuum (suction) to draw fuel into the engine. The amount of air-flow through the carburetor determines the amount of fuel used. This automatically maintains the correct air-fuel ratio. A mechanical or an electrical fuel pump draws fuel out of the tank and delivers it to the carburetor.

drive train

This transfers turning force from the engine crankshaft to the drive wheels. Configurations vary, depending on vehicle design.

hybrid vehicle

This type of vehicle uses two methods of propulsion - an internal combustion engine and a large electric motor-generator - to help improve vehicle performance (acceleration), increase fuel economy (gas mileage), and reduce air emissions (air pollution).

computer system

This uses electronic and electrical devices to monitor and control various systems in the vehicle, including the fuel, ignition, drive train, safety and security systems.

transmission

This uses various gear combinations, or ratios, to multiply engine speed and torque to accommodate driving conditions. Low gear rations allow the vehicle to accelerate quickly. High gear ratios permit lower engine speed, providing good gas mileage.

strokes

Up or down movements.

coolant

Water and antifreeze solution. This collects heat from the hot engine parts and carries it back to the radiator.

ignition coil

When triggered, this produces a high voltage output to 'fire' the spark plugs.