2018 hsc automotive mechanical technology marking guidelines

NSW Education Standards Authority

2018 HSC Automotive Mechanical Technology Marking Guidelines

Section I

Multiple-choice Answer Key

Question Answer 1 A 2 D 3 C 4 D 5 B 6 B 7 A 8 B 9 D

10 B 11 C 12 C 13 D 14 C 15 A

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Section II

Question 16 (a) Criteria Marks

• Identifies the tool correctly • Lists TWO types of measurements that the tool is used for in an

automotive workshop 3

• Identifies the tool correctly • Names ONE type of measurement that the tool is used for in an

automotive workshop 2

• Identifies the tool correctly or lists ONE type of measurement that the tool is used for in an automotive workshop 1

Sample answer:

• Dial gauge • End float (thrust) • Run-out (axial and radial)

Question 16 (b) Criteria Marks

• Provides a sound description of the processes used when checking a disc rotor for serviceability 3

• Provides some description of the processes used when checking a disc rotor for serviceability 2

• Provides a basic description of the processes used when checking a disc rotor for serviceability 1

NESA 2018 HSC Automotive – Mechanical Technology Marking Guidelines

Sample answer:

• Mount the magnetic base on a sturdy suspension component • Set the dial gauge at 90° to the disc • Preload the dial gauge • Zero the dial gauge • Rotate disc 360° to determine run-out, based on needle deflection • Use a micrometer to check disc thickness

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• Outlines at least TWO methods to quickly identify the leaking fluid correctly 2

• Outlines ONE method to quickly identify the fluid correctly 1

Sample answer: Any two: • Check the colour • Smell the fluid • Feel the texture of the fluid • Identify the location beneath the vehicle


• Clearly explains THREE possible reasons why milky coolant is observed

• inside a radiator Uses correct industry terminology and identifies related components 5

• Provides a detailed explanation for the reasons given • Explains possible reasons why milky coolant is observed inside a radiator • Uses industry terminology 3–4 • Provides a limited explanation for the reasons given • Explains ONE possible reason why milky coolant is observed inside a

• radiator Uses limited industry terminology 1–2

• Provides a basic explanation for the reason given


Sample answer: Any three: • Head gasket – failure between oil and coolant seal • Cracked cylinder head – water leaking between coolant and oil galleries • Cracked engine block – water leaking between coolant and oil galleries • Cracked oil cooler – engine oil leaking into cooling system • Cracked transmission cooler – transmission fluid leaking into cooling system

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• Provides a clear explanation of why diesel engines run at a higher compression ratio compared to petrol engines 2

• Provides a basic explanation of why diesel engines run at a higher compression ratio compared to petrol engines 1

Sample answer: Diesel fuel requires heat created by air compression to ignite the fuel.


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Provides a comprehensive explanation of how the energy stored in petrol and diesel fuels is converted to torque at the flywheel

Uses correct industry terminology 5

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Provides a sound explanation of how the energy stored in petrol and diesel fuels is converted to torque at the flywheel Uses some industry terminology

3–4

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•

Provides a basic explanation of how the energy stored in petrol and diesel fuels is converted to torque at the flywheel Uses correct industry terminology

2

• Provides general information on energy conversion 1

Sample answer: When petrol or diesel fuel is combined with the correct air ratio and compressed, then ignited, energy is released in the form of heat. This heat expands the air in the cylinder forcing the piston down, therefore converting chemical energy into heat energy then to kinetic energy. The piston is connected to the con-rod which rotates the crankshaft and turns the flywheel.


• States the danger of working with high voltage 1


Sample answer: Be aware of high operating voltages of HID globes as this could cause death.

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• Provides a sound description of how an electrical circuit is tested for correct operating voltage 3

• Provides some description of how an electrical circuit is tested for correct operating voltage 2

• Demonstrates a limited understanding of how an electrical circuit is tested for correct operating voltage 1

Sample answer: The following tools and process are used to determine the amount of voltage drop: • use a multimeter • use workshop specifications • test battery reference voltage • test supply voltage • test circuit earth points • calculate voltage drop using the difference obtained between the reference and load

voltages.

Question 19 (c) Criteria Marks

• Provides a thorough description of why a wiring diagram is used in the troubleshooting process when diagnosing a fault 4

• Uses correct industry terminology • Provides a sound description of why a wiring diagram is used in the

troubleshooting process when diagnosing a fault 2–3 • Uses basic industry terminology • Provides a basic description of a wiring diagram 1


Sample answer: A wiring diagram is the first place to go to when identifying an electrical fault. The reasons for this are to quickly locate: • power supplies • earth positions • plug locations • electrical component locations • harness secure points. This gives the technician a ‘road map’ to follow to speed up processes in diagnosing.

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• Clearly explains the initial checks to identify if a vehicle’s wheels are aligned prior to placing the vehicle on a wheel alignment machine 3

• Uses industry terminology • Provides some explanation of the initial checks to identify if a vehicle’s

wheels are aligned prior to placing the vehicle on a wheel alignment machine 2

• Uses some industry terminology • Provides some relevant information 1

Sample answer: The initial visual and physical checks that could be used to identify if a vehicle’s wheels are aligned prior to placing the vehicle on a wheel alignment machine include: • bearing damage/free play • suspension damage • bush damage/play • steering linkage/rack damage.


• Provides a thorough explanation of the diagnostic process to identify FOUR components related to the damaged area 4

• Uses industry terminology • Provides a sound explanation of the diagnostic process to identify TWO

to THREE components related to the damaged area 2–3 • Uses some industry terminology • Provides some relevant information 1


Sample answer: The diagnostic process to assess four related steering and suspension components that would be damaged due to the accident would include initially visually inspecting the vehicle while stationary for damaged components. The vehicle would need to be raised. The components that could be checked include (any FOUR): • lower control arm for bend • ball joint for freeplay • tie rod for bend and toe • strut/shock absorber tested for bounce and rebound and visually inspected for bend • wheel bearing for excessive noise and freeplay • lower control arm for physical damage and damaged fixture points.

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Section III


• Provides a comprehensive explanation of how modern engines achieve lower emissions and higher efficiency compared to older carburettor systems

• Demonstrates a comprehensive understanding of the fuel system differences

• Provides a logical and cohesive response • Uses industry terminology

5

• Provides a sound explanation of how modern engines achieve lower emissions and higher efficiency compared to older carburettor systems

• Demonstrates a sound understanding of the fuel system differences • Provides a logical response • Uses some industry terminology

3–4

• Provides a basic explanation of how modern engines achieve lower emissions and higher efficiency compared to older carburettor systems

• Demonstrates a basic understanding of the fuel system differences 1–2

Answers could include: Modern engines run leaner mixtures in comparison to older carburettor systems. Modern engines achieve low emissions by: • modern sequential injection:

– finely atomised fuel sprays into the manifold allowing for quicker vaporisation in a warm manifold

– timed injection to inject at the precise time on the intake stroke when air speed is highest to allow for best air/fuel mixing for best combustion outcome

– fuel is injected under pressure and HCs are minimised, as injection is deep within the manifold.

• modern manifolds: – alloy and lightweight, better heat absorption and dissipation – shaped runners after plenum to ensure maximum airflow to cylinders – variable manifolds to suit low speed and high speed performance applications, keeps

air speed high for best engine efficiency – multiple throttle bodies to ensure no air lag and engine performance is instant.

• ignition systems: – high energy coil on plugs (COP) individual – ensure max coil saturation one per plug

for best efficient spark – HEI ignition effectively lights up leaner mixtures to ensure a complete burn – programmable timed ignition for best burn to effectively combust all the air fuel charge – knock sensors to ensure maximum advance for best efficient burn.

• exhaust systems: – catalysts to convert harmful emitted gases – better flowing exhausts to ensure better cylinder scavenging – O2 sensors in exhaust to monitor the air to fuel ratio to meet 14.7:1.

• cam change: – cam profile change to reduce valve overlap to ensure no lost gases or HCs at lower

RPM

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– cam timing. • head change:

– alloy causes faster heat take up and faster dissipation therefore less emissions – different combustion chamber design to enable best burn to reduce harmful emissions – alloy heads allow for leaner mixtures due to holding less latent heat.

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• Provides a comprehensive explanation of how to modernise and update the classic vehicle to meet emissions standards

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Demonstrates a comprehensive understanding of the fuel emission systems Provides a logical and coherent response

9–10

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Provides a sound explanation of how to modernise and update the classic vehicle to meet emissions standards Demonstrates a sound understanding of the fuel emission systems Provides a logical and/or coherent response

6–8

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Provides some explanation of how to modernise and update the classic vehicle to meet emissions standards

Demonstrates some understanding of the fuel emission systems Provides a logical response

3–5

• Provides a basic explanation of how to modernise and update the classic vehicle to meet emissions standards 1–2

• Demonstrates a basic understanding of the fuel emission systems


Answers could include:

• Engine: – install alloy heads – modify combustion chambers – install alloy manifold – install programmable EFI/lgn system, modern ECU with wiring loom from similar

engine size – change camshaft to suit new EFI – install higher combustion slipper pistons – install better flowing exhaust, with catalytic convertors and O2 sensors – install EFI system and wiring harness – install injectors – install knock sensors – install electric thermo fans – install COP units – install electric water pumps.

• Transmission: – transmission automatic or manual with more gears, better ratio spread for emission test – lower gears for starting take off – overdrive gears for cruising efficiency – alloy tail shaft or carbon to reduce weight for efficiency.

• Brakes (as a side): – better brakes to cope with the power output of a more efficient engine – 4 spot fixed alloy calipers, lighter weight for efficiency and better braking efficiency.

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Section IV

Question 22 Criteria Marks

• Provides a comprehensive explanation of how the automotive industry is addressing the disposal and recycling of automotive components and fluids

• Provides clear links to environmental sustainability • Provides a systematic and reasoned approach • Uses specific industry terminology

13–15

• Provides a detailed explanation of how the automotive industry is addressing the disposal and recycling of automotive components and fluids

• Provides links to environmental sustainability • Provides a reasoned approach • Uses specific industry terminology

10–12

• Provides a sound explanation of how the automotive industry is addressing the disposal and recycling of automotive components and fluids

• Provides some links to environmental sustainability • Uses industry terminology

7–9

• Provides some explanation of how the automotive industry is addressing the disposal and recycling of automotive components and fluids

• Provides some environmental considerations • Uses some industry terminology

4–6

• Provides general information on the disposal and recycling of automotive components 1–3

Answers could include: The automotive industry is facing unprecedented issues in becoming environmentally sustainable. Currently a large percentage of a vehicle is not recyclable. As recycling costs more than disposing in landfill, manufacturers are now becoming more environmentally responsible due to public and government pressure.

• Manufacturers are using less-damaging substances, for example, materials in clutches and brakes. They are using parts which are less disposable, such as cartridge oil and fuel filters. Car air conditioning units are also becoming more sustainable with the use of new gases and legislation for recycling greenhouse-producing gas.

• Batteries are now mostly recyclable. Some hybrid batteries can be repaired or are fully recyclable and are supported by dealership programs to be re-used.

• In Europe some countries have mandated that 70% of a vehicle must be fully recycled and a goal of 100% to be soon achieved.

• Car manufacturers are also using communication platforms within the vehicle to reduce the quantity of wiring. This is due to CAN bus communication. Copper wire can be re-used and recycled.

• The use of aluminium is increasing which decreases the vehicle’s weight, thereby reducing emissions. It is also desirable to recycle aluminium as the energy needed to create it is much greater than recycling.

• The use of recycled components reduces the manufacturing of new parts.

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• Local repair workshops use waste disposal methods that include oil separaters, package and parts recycling.

• Also environmental control, including noise, bunding and hazardous waste control. • Repair of existing components while more time-consuming is better for the environment.

Plastic components can be recycled into other components but not necessarily used in the automotive industry. The use of water-based paints lessens the use of mineral thinners that are dangerous to the environment. Water-based paints have less impact on the environment and the operator’s health. Recycling of all thinners and paints is now being encouraged within the industry. Contaminated waste and greywater is now recycled. Parts packaging is now being recycled. Ventilation filters are now installed in body repair shops to reduce surrounding pollution.

• Extended oil change intervals have reduced the amount of servicing required. Used engine oil makes up the bulk of waste from automotive workshops. Used engine oil can be filtered and re-used in industry as fuel oil for heaters and furnaces.

• Electric steering systems have replaced hydraulic steering systems in vehicles, thereby eliminating the need to flush or service the oil in hydraulic steering systems.

• Smaller capacity and higher efficiency cooling systems as well as long life coolants are being used. This reduces the number of coolant changes a vehicle requires during servicing.

• Fill-for-life transmissions have reduced the need to service the transmission. • Future cars will be electric and by nature will be more environmentally sustainable due to

fewer fluid and maintenance requirements. Electric motors are also fully recyclable.

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2018 HSC Automotive Mechanical Technology Mapping Grid Section I

Question Marks HSC content – focus area

1 1 (Mandatory) Safety — risk assessment – p29

2 1 (Mandatory) Working in the automotive industry and workplace — working with others – p43

3 1 (Mandatory) Sustainability — environmentally sustainable work practices – p34

4 1 (Stream) Mechanical technology — operation of automotive tools and equipment – p52

5 1 (Stream) Mechanical technology — vehicle mechanical systems and components – p47

6 1 (Stream) Mechanical technology — operating principles of mechanical systems and components – p48

7 1 (Mandatory) Safety — safe work procedures and practices – p29–30

8 1 (Stream) Mechanical technology — electrical fundamentals – p49–50


10 1 (Mandatory) Working in the automotive industry and workplace — working in the industry – p40

11 1 (Stream) Mechanical technology — operation of automotive tools and equipment – p52





Section II


16 (a) 3 (Stream) Mechanical technology — tools and equipment – p52

16 (b) 3 (Stream) Mechanical technology — tools and equipment – p52

17 (a) 2 (Stream) Mechanical technology — fault-finding – p48

17 (b) 5 (Stream) Mechanical technology — fault-finding – p48

18 (a) 2 (Stream) Mechanical technology — operating principles of mechanical systems and components – p48

18 (b) 5 (Stream) Mechanical technology — operating principles of mechanical systems and components – p48

19 (a) 1 (Mandatory) Safety — risk management – p29

19 (b) 3 (Mandatory) Troubleshooting and problem-solving — troubleshooting processes – p36


19 (c) 4 (Mandatory) Troubleshooting and problem-solving — fault or problem resolution – p36

20 (a) 3 (Mandatory) Troubleshooting and problem-solving — troubleshooting processes – p36

20 (b) 4 (Mandatory) Troubleshooting and problem-solving — fault or problem resolution – p36

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Section III


21 (a) 5 (Stream) Mechanical technology — operating principles of mechanical systems and components – p48

21 (b) 10 (Stream) Mechanical technology — operating principles of mechanical systems and components – p48

Section IV


22 15 (Mandatory) Safety — safe work procedures and practices – p29 (Mandatory) Sustainability — environmentally sustainable work practices – p34

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2018 hsc automotive mechanical technology marking guidelines

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