Question 1

Diesel Cycle

Accepted Answer

Four-stroke combustion cycle used by diesel engines: intake, compression, combustion, exhaust.

Question 2

Glow Plug

Accepted Answer

Assists in starting diesel engines by heating air in the combustion chamber.

Question 3

Fuel Injector

Accepted Answer

Delivers fuel into the combustion chamber at the right time and in the right amount.

Question 4

Turbocharger

Accepted Answer

Uses exhaust gases to compress intake air, increasing power output.

Question 5

Intercooler

Accepted Answer

Cools compressed air from the turbocharger to increase density and performance.

Question 6

Common Rail Injection

Accepted Answer

A type of fuel injection system where the fuel supply to all the injectors comes from a common rail.

Question 7

High Pressure Fuel Pump

Accepted Answer

Pressurizes diesel fuel for injection into the engine.

Question 8

Cylinder Liner

Accepted Answer

Sleeve in which the piston moves in a diesel engine.

Question 9

Main Bearing

Accepted Answer

Supports the crankshaft and allows it to rotate inside the engine block.

Question 10

Connecting Rod

Accepted Answer

Links the piston to the crankshaft and transfers motion and forces.

Question 11

Exhaust Gas Recirculation (EGR)

Accepted Answer

Reduces nitrogen oxide (NOx) emissions by recirculating exhaust gases into the engine intake.

Question 12

Diesel Particulate Filter (DPF)

Accepted Answer

Catches and stores exhaust soot to reduce emissions from diesel engines.

Question 13

Selective Catalytic Reduction (SCR)

Accepted Answer

An advanced active emissions control technology system that injects a liquid-reductant agent through a special catalyst into the exhaust stream of a diesel engine.

Question 14

DPF Regeneration

Accepted Answer

Process where accumulated soot in DPF is burned off at high temperature to leave only a small amount of ash.

Question 15

Compression Ratio

Accepted Answer

Ratio of the cylinder's volume at BDC to its volume at TDC.

Question 16

Cylinder Firing Order

Accepted Answer

The sequence in which cylinders are ignited for optimal engine balance and smoothness.

Question 17

Diesel Knock

Accepted Answer

Noise made by premature ignition of the fuel-air mixture in the cylinder; also known as detonation.

Question 18

Wet Cylinder Liner

Accepted Answer

Cylinder liner that is in direct contact with engine coolant for superior cooling.

Question 19

Dry Cylinder Liner

Accepted Answer

Cylinder liner that is in direct contact with the engine block.

Question 20

Unit Injector

Accepted Answer

A type of fuel injector where the injector is a combined pump and nozzle assembly with its own compression device.

Question 21

Fuel Quality Sensor

Accepted Answer

Monitors the quality and composition of diesel fuel to optimize engine performance and emissions.

Question 22

Fuel Water Separator

Accepted Answer

Removes water from diesel fuel to prevent damage to the engine.

Question 23

Fuel Filter

Accepted Answer

Removes contaminants from diesel fuel before it is injected into the engine.

Question 24

Cold Start System

Accepted Answer

Assists in starting a diesel engine in cold weather.

Question 25

Oil Cooler

Accepted Answer

Cools engine oil to maintain optimal engine temperature.

Question 26

Oil Pressure Sensor

Accepted Answer

Monitors engine oil pressure to ensure it is within safe operating limits.

Question 27

Crankshaft Position Sensor

Accepted Answer

Monitors the position or rotational speed of the crankshaft.

Question 28

Camshaft Position Sensor

Accepted Answer

Monitors the rotational position of the camshaft.

Question 29

Fuel Temperature Sensor

Accepted Answer

Monitors the temperature of the diesel fuel.

Question 30

Air Filter

Accepted Answer

Removes particulates from air before it is used in the combustion process.

Question 31

Timing Gear

Accepted Answer

Controls the timing of the valves and the ignition system.

Question 32

Drive Belt

Accepted Answer

Transfers power from the engine to accessories like the alternator and water pump.

Question 33

Piston Ring

Accepted Answer

Seals the combustion chamber, transfers heat from the piston to the cylinder, and regulates engine oil consumption.

Question 34

Cylinder Head Gasket

Accepted Answer

Seals the cylinder head to the engine block and prevents leakage of engine fluids.

Question 35

Diesel Oxidation Catalyst (DOC)

Accepted Answer

A catalytic converter that promotes the oxidation of harmful exhaust gases, such as carbon monoxide and hydrocarbons, into less harmful compounds.

Question 36

Variable Geometry Turbocharger (VGT)

Accepted Answer

A turbocharger with adjustable vanes that optimize boost pressure at different engine speeds, improving efficiency and response.

Question 37

Exhaust Manifold

Accepted Answer

Collects exhaust gases from the cylinders and directs them to the exhaust system.

Question 38

Throttle Position Sensor (TPS)

Accepted Answer

Monitors the position of the throttle valve to determine the desired engine load.

Question 39

Electronic Control Module (ECM)

Accepted Answer

The main computer that controls and monitors various engine functions and systems.

Question 40

Cylinder Head

Accepted Answer

Covers the combustion chambers and houses the valves, spark plugs, and fuel injectors.

Question 41

Emissions Control Systems

Accepted Answer

Systems designed to reduce harmful emissions from diesel engines, including DPF, SCR, and EGR.

Question 42

Crankcase Ventilation System

Accepted Answer

Removes gases from the engine's crankcase and prevents pressure buildup.

Question 43

Valve Clearance

Accepted Answer

The gap between the valve stem and the rocker arm or camshaft, which affects engine performance and longevity.

ASE Transit Bus Certification Flashcards: H2 - Diesel Engines