Heavy Duty Technician Practice Exam

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• What can be used to prevent small electric shocks to individuals exiting a bus?
• What does DC stand for in electrical terms?
• A self powered test light can provide an indication of what type of circuit condition?
• Which process results in improved combustion in an engine?
• To maintain peak combustion pressure at 10 degrees after TDC, the injection timing must vary with what factors?
• What is a typical idle injection quantity in a diesel engine?
• At what pressure range do electronic controls open the nozzles in variable nozzle systems?
• What type of load must a scaffold be designed to support?
• True or False: Deep bowl chambers create high turbulence.
• Higher compression ratios in engines typically lead to improved:
• Which type of current is characterized by a consistent direction of electron flow?
• What is the purpose of the fuel vapor return line?
• What is the pitch of a metric micrometer?
• A single diode in a stator winding will produce?
• Alternator brushes will carry the full?
• What does AC stand for in electrical terms?
• What is the reason for retarding injection timing during cranking?
• Which testing tool is most appropriate for locating a grounded circuit?
• What can early ignition during the intake stroke lead to in SI engines?
• In electronically controlled engines, what can the PTO or cruise control button adjust?
• How can more power be produced with the same amount of fuel in an engine?
• When diagnosing electrical problems, which type of circuit should be investigated if the lights remain off?
• What is one potential drawback of using deep bowl combustion chambers?
• What is the approximate flame temperature of diesel fuel?
• In a DC circuit, increasing resistance while maintaining voltage has what effect on amperage?
• What is AC (Alternating Current)?
• What is the standard maximum belt deflection for an air brake system air compressor?
• What are the two common types of Direct Injection (DI) chambers?
• White exhaust smoke in an engine can indicate:
• What effect does high temperature have on the combustion process?
• How many seconds of space should you maintain ahead when driving a 100ft twin trailer combination at 50 mph on a dry road with good visibility?
• What are the four factors that determine the amount of resistance in a circuit?
• True or False: Stronger magnets have more flux.
• Voltage output of the alternator is controlled by regulating the?
• In air brake systems, what might a belt deflection measurement outside of 12 to 18 mm indicate?
• True or False: Thicker windings consume more current but maintain a strong magnetic field when the voltage drops.
• What happens to amperage if resistance increases while voltage remains constant?
• If resistance is held constant, what will happen to amperage if voltage increases?
• Which component is essential for the operation of a self powered test light?
• What is a possible cause of white exhaust smoke?
• What phenomenon occurs when friction is used to generate electricity?
• True or False: Excess combustion air keeps diesel exhaust temperatures cooler than SI engines burning at stoichiometric ratios.
• True or False: Engines with high compression ratios have reduced mechanical efficiency due to increased friction losses.
• Which kind of test light contains a 1.5 V battery?
• What is the designation for electrical circuits that have high amounts of current through heavier conductors?
• Which methods can generate electron flow using magnetic fields?
• What is the recommended action if a timing chain has excessive deflection?
• DC current moves electrons only in one direction continuously from _____________ to ___________.
• What does flux represent in a magnetic context?
• What happens to the cylinder temperature as the piston rises in the cylinder?
• Pintle nozzles operate with lower nozzle opening pressure than which other type of nozzle?
• Why is the IDI combustion chamber common in automotive applications?
• How should you check the slack adjuster?
• Which situation describes when you would most likely use a self powered test light?
• Why is it important to test for short circuits?
• True or False: Offset DI can be less expensive but may create uneven piston crown temperatures and thrust loads.
• What is the auto-ignition temperature?
• What role does turbulence play in combustion efficiency?
• What is a Quiescent Chamber?
• Mutual induction involves?
• True or False: Air has a less reluctance to magnetic lines of force.
• What could lead to vibration and a hard bang over uneven terrain, indicating a drive shaft problem?
• How many heating elements does an ISS have?
• What is the first action to take before using a piece of lifting equipment?
• Which of the following is NOT a size of wire available for MIG welding?
• True or False: IDI chambers use a pre-combustion chamber formed in the cylinder head.
• What is a possible cause for chattering on the cylinder rod and a noisy pump on a cushion ride system?
• What is wet stacking and what's the primary cause of it?
• What does the acronym MOS stand for in semiconductor technology?
• A bias ply tire on a heavy-duty vehicle is best suited for what type of application?
• Engines are designed to produce peak combustion pressure at what degrees after TDC?
• If amperage is held constant, voltage must _____________ if resistance _____________.
• What is the minimum cranking speed for a four-stroke diesel engine?
• How much more power do modern engines produce compared to older steam engines?
• What do we call materials that do not conduct electricity easily?
• Where must the timing marks face when installing camshaft gears?
• Most IDI Chambers require glow plugs for starting aids?
• If voltage is held constant and resistance decreases, what happens to amperage?
• How does load change affect the timing of fuel injection?
• Today's SI engines typically operate at which range of compression ratios?
• Which of the following components is part of an alternator's function to regulate voltage output?
• What is the average temperature produced from preignition air temperatures?
• What benefit comes from having smaller clearance volumes in diesel engines?
• What is the average compression ratio based on common values for DI chambers?
• What is the typical compression pressure range when using an intercooler and turbocharger?
• What prevents the engine from shutting off after a remote start when the brake is applied?
• What can cause the steering wheel to rotate by itself on an articulating steering system?
• Who is credited with inventing the diesel engine?
• What is the newest innovation to glow plug mechanisms that includes a pressure sensor?
• At what temperature does aluminum melt in degrees Celsius?
• What is the purpose of using octane boosters in SI engines?
• What is a common characteristic of diesel fuel injection?
• Why is scavenging of exhaust gases important in diesel engines?
• What is the percentage by which DI is better in fuel efficiency compared to IDI?
• What is combustion slobber?
• What does Hertz (Hz) measure in electrical currents?
• Which WHMIS Class symbol features only a flame?
• What are the factors that make DI Combustion Chambers popular?
• What is defined as the time period between fuel injection and ignition in a combustion chamber?
• What is a characteristic of diesel engines compared to SI engines regarding combustion pressure?
• True or False: Magnetic fields are the most common method for generating electricity in heavy-duty vehicles.
• What happens to the brushes in an alternator when field current is low?
• Pintle nozzles can have opening pressures that range between which values?
• What are the two types of injector nozzles used in IDI systems?
• What does it indicate when a wheel has developed "Chording"?
• What is the primary use of stepped resistors in automotive applications?
• Which of the following statements about large diameter wires is correct?
• What can a self powered test light be used to find?
• How does increasing the battery voltage affect electron flow?
• What are the normal cranking speeds for medium and large bore diesel engines?
• What must be present for proper mixing of air and fuel in a combustion chamber?
• In which type of valve are the system and circuit relief valves typically found?
• True or False: Direct injection engines warm up quickly and reach operating temperature when idled.
• What might an increase in wheel temperature indicate about a vehicle's braking system?
• What type of engine relies on spark plugs for ignition?
• High engine thermal efficiencies are achieved using DI Chambers because of what ratio characteristics?
• For a circuit using DC current, if the resistance doubles, what will happen to the amperage?
• When installing bearings, what is a critical consideration?
• True or False: Quiescent Chambers can reduce emissions by increasing injection pressures and the number of spray holes at the injector tip.
• Why is adequate air turbulence crucial in a DI chamber?
• True or False: Thinner windings can be used for continuous operation but lose strength when voltage drops.
• What is typically the primary function of a test light?
• In terms of engine design, what characteristic does a DI chamber improve compared to an IDI chamber?
• True or False: MOS types have more resistance and conduct less current than older semiconductors.
• What is stratified combustion?
• What characteristic allows a thinner winding to operate continuously despite voltage drops?
• A battery cable terminal with 0.01 ohms will experience what voltage drop with one amp of current?
• What WHMIS Class symbol features a skull?
• Generally, idle speed is kept at what range of rpm?
• What issue might cause a crawler dozer with an electronically controlled hydrostatic steering system to pivot left only when moving forward or reverse?
• What unit is used when calculating heat output?
• What is the maximum safe working pressure for acetylene?
• Are the heating elements in an ISS connected in parallel?
• What is the minimum tensile strength for an AWS E7018 electrode?
• What is performed to test the pickup coil in an electronic ignition?
• True or False: AC current is measured in Hertz (Hz)?
• What is one major disadvantage of DC current?
• Grease is made up of approximately what percentage of oil?
• What are the two primary types of electrical fuel pumps?
• What does pre-ignition detonation refer to?
• What type of flame is used when welding brass on bronze?
• A scaffold must be designed to support how many times the imposed load?
• What is flux density?
• What is the typical range of sizes for MIG welding wire?
• True or False: More lines of force mean the lesser the magnetic field.
• Which property of a semiconductor allows it to switch between conduction and insulation?
• What is the most important material used to construct electrical devices that can act as both conductors and insulators?
• When combustion chambers burn fuel in layers that vary in air-to-fuel ratios, this is known as?
• Which part of an alternator is stationary?
• In vehicle diagnostics, what does it generally indicate if a circuit is open?
• What is the maximum allowed chain deflection in inches for a timing chain before it should be replaced?
• What type of rectification does a three-phase alternator typically use for its output?
• Diesel engines are also referred to as?
• True or False: The greater the difference in electron concentration between the two points, the higher the battery voltage?
• What is the formula used to calculate piston area?
• What must happen if the voltage decreases in a circuit?
• Gear rattle is minimized at the rear of the engine because the __________ smooths out crankshaft speed changes.
• A truck or bus battery and chassis are an example of _____________ flow takes place.
• Which electrode type might you choose for welding applications requiring higher tensile strength?
• In an alternator, the current producing windings are?
• What type of glow plug system can heat up to operating temperature very quickly?
• Which of the following factors affects the performance of an air brake system?
• Where are system and circuit relief valves commonly installed in heavy equipment?
• What is a key characteristic of a biodegradable fluid?
• True or False: IDI combustion chambers use lesser compression ratios to compensate for lower thermal efficiency.
• What happens when air is compacted into a smaller volume at a high temperature?
• What are the phases in a Direct Injection pressure volume cycle?
• For what purpose are wire-round (power) resistors typically made?
• Which of the following concerns is associated with pencil fuel injectors?
• What characteristic makes ROM necessary for an Engine Control Module?
• What should be checked to ensure safety when using lifting equipment?
• True or False: Offset DI engines typically use four valves per cylinder.
• What effect does a decrease in resistance have on current flow in a circuit?
• How accurate are steel rules when measured in SI units?
• What is the acetylene pressure in a full cylinder approximately?
• What is the metric term for Energy?
• What does ESD stand for?
• What is a major drawback of SI engines?
• What is the maximum auto ignition temperature required from North American fuel standards?
• What type of tool is influenced by magnetic flux to sense field strength?
• True or False: Cooler combustion temperatures can warm up a diesel engine at idle speed without load.
• What type of circuit operates semiconductors and uses less amperage to process signals?
• A pilot injection of fuel is typically done at what angle before the main injection event?
• What effect does an integrated pressure-sensing glow plug have?
• What does smaller clearance volume in an engine enhance?
• What noise is typically associated with pre-ignition detonation?
• Which type of diesel fuel injector is characterized as having inward and outward opening mechanisms?
• What is done to detect a leak on the primary side of a diesel engine fuel system?
• What conditions speed up chemical reactions and increase the likelihood of fuel and oxygen reacting?
• In the context of acetylene, what does the term "Brittle Fracture" refer to?
• What is the recommended maximum idling time for late model engines?
• Do manufacturers provide a recommended idle speed on the emission decal?
• What is the minimum tensile strength for an E6010 electrode?
• True or False: Auto Ignition temperature in a gas engine is higher than in diesel engines.
• What is the by-product of combustion from diesel engines that consists of unburned fuel, soot, and lubricating oil?
• What is a more common pre-ignition temperature?
• Which type of memory is typically used for permanent storage in an Engine Control Module (ECM)?
• Fixed resistors are designed for and made of which type of material?
• What type of injection does a Basic Injection System use?
• Charging circuit indicator lamps are installed so that they will not light when?
• What term describes the temperature at which fuel produces adequate vapor to ignite?
• What type of energy is converted by resistance in electrical elements?
• Is it true that the increments for adjusting fast idle speed in electronically controlled engines are also adjustable?
• True or False: Do large diameter wires have less resistance?
• In oxyacetylene torch cutting, what is the typical cutting pressure measured in kPa?
• What typically happens to the combustion temperature in stratified combustion?
• True or False: Direct Injection (DI) chambers generally require starting aids like glow plugs or air intake heaters.
• What does prolonged engine idle mainly cause?
• In AC current, what term describes the line in a graph that curves up and down?
• What tool would be most effective in measuring high current levels in a vehicle circuit?
• What is the problem in a manual transmission that is noisy under load in all reduction gears?
• What is a common problem when starting a diesel engine?
• Among the following, which is NOT a function of a test light?
• What injection strategy regulates the amount of fuel injected per crank angle rotation?
• What does SI stand for in ignition systems?
• In SMAW accessories, what does the letter 'E' represent?
• What type of resistors can conduct either heavy or light amounts of current?
• In what form is fuel injected in diesel engines for efficient combustion?
• True or False: Wire rope will not conduct electricity.
• Which of the following is a characteristic of an IDI engine?
• What phenomenon is observed in a current-carrying wire when the current is changing?
• An alternator stator with three windings usually has a rectifier with?
• What is the typical auto ignition temperature range for fuels?
• True or False: The resistance of a conductor is affected by its temperature.
• True or False: Most semiconductors today are made from metal oxides.
• What percent of the base fluid must a bio-degradable fluid be able to break down in a specific period of time?
• What is the peak cylinder combustion pressure that larger engines can typically produce?
• Which type of flame is characterized by an excess of oxygen?
• How fast can an ISS build up instant heat to operating temperature?
• Which of the following statements is true regarding diesel engine operation?
• Which component in an ISS heats quickly and efficiently for starting purposes?
• What is the melting point range for aluminum alloy pistons?
• What is the impact of a grounded circuit in an electrical system?
• True or False: Do longer wires have less resistance?
• What does NOP stand for in the context of fuel injection?
• In a diesel engine, how do higher injection pressures affect combustion?
• What is reluctance in terms of magnetic fields?
• In a non-displacement pump, what is generated within the eye of the pump?
• In an alternator, the field winding is part of the?
• Which of the following is a common combustion by-product?
• What will happen to voltage if resistance decreases while amperage is held constant?
• Torsional vibration occurs when the __________ speeds up and slows down.
• What is one common usage for a multimeter in vehicle diagnostics?
• True or False: Most late model engines use quiescent bowls combined with high-injection pressurization to mix air and fuel to achieve lower NOx emissions.
• What type of combustion chamber was most commonly used in automotive applications during the 1990s?
• What is the typical compression ratio range in a DI chamber for most on-highway diesel engines?
• Approximately what percentage of the cylinder volume does the IDI pre-combustion chamber hold?
• What general issue is indicated by a drive shaft that is out of phase?
• What is the most commonly used material for electrical conductors?
• True or False: Increasing the number of wire loops increases the magnetic field strength.
• What effect does a higher compression ratio have on engine performance?
• Which of the following best describes a short circuit?