Obami | Digital Stakeholder Experiences

QUESTION 1: - SINGLE - CHOICE QUESTIONS

Marks: 20

Question 1:

FORMULA SHEET

Download this formula sheet for this exam.

Attached Resource:

6998103f-eecb-478e-a486-cb04cf69c89d.pdf

Your Answer:

ok

Question 2:

What is the advantage of down-cut milling?

Your Answer:

The strain on the arbor and cutter is less.

Finish obtained is finer.

More vibration is experienced.

Built-up pressure is developed.

Question 3:

Which ONE of the following safety procedures does NOT relate to the cylinder leakage tester?

Your Answer:

Use water to remove dust around the spark-plug area.

Clean and remove the oil filler cap.

Do not exceed the prescribed pressure in the test cylinder.

The tester must fit properly and be well tightened in the spark-plug hole or injector hole.

Question 4:

What is the function of a gas analyser?

Your Answer:

Analyse inlet gases

Analyse oil gases

Analyse fuel gases

Analyse exhaust gases

Question 5:

The main reason for using a torsion tester is to measure the ability of metal to … without breaking.

Your Answer:

bend

twist

elongate

shorten

Question 6:

Alloys can …

Your Answer:

reduce electrical conductivity.

increase resistance to corrosion.

reduce strength and hardness.

alter insulation properties.

Question 7:

Thermosetting plastic materials are materials that …

Your Answer:

can be stretched and return rapidly to their original shape.

cannot be softened and reshaped by reheating.

soften under heat and become hard when cooled.

stay soft after reheating.

Question 8:

Identify the type of milling cutter shown in FIGURE 1.1 below.

(See attached resource)

Attached Resource:

b553872f-2d2f-44c1-b1dd-5cf45f8f6b6e.png

Your Answer:

Dovetail slot cutter

Convex cutter

Cylindrical/Helical cutter

Single corner rounding cutter

Question 9:

Which lathe operation is shown in FIGURE 1.2 below?

(See attached resource)

Attached Resource:

9fecffdc-bbfe-4bf9-aa7f-a35f9038ac31.png

Your Answer:

Diameter turning

Thread cutting

Facing off

Boring

Question 10:

Upcut milling is also known as …

Your Answer:

gang milling.

slot milling.

climb milling.

conventional milling.

Question 11:

What is the reason for using a free-bend test?

Your Answer:

To measure the ductility of the weld metal

To test the skill of the welder

To train welders

To approve welds according to certain standards

Question 12:

What is the advantage of a helical cutter?

Your Answer:

Vibration experienced by the machine is more.

Narrow cuts may be made.

No side thrusts due to sliding action of the cutter.

Wider cutters may be used.

Question 13:

Tensile stress can be defined or described as an internal force in a material resisting …

Your Answer:

a shearing load.

a pulling load.

a pushing load.

any load.

Question 14:

What is understood by the term Young's modulus?

Your Answer:

The force value required to produce a unit area in a tensile test specimen

The ratio between stress and strain in a metal, provided that the limit of elasticity is not exceeded

A measurement of the extension or contraction of material due to the load experienced

A ratio of the deformation by application of an external force

Question 15:

Which step in adjusting the tension in the chain of a chain drive does FIGURE 1.3 below show?

(See attached resource)

Attached Resource:

6967908e-efe0-400c-9f2f-477fb96483f3.png

Your Answer:

Check the distance between the centres

Slacken the clamp bolts and screw the adjusting bolts in or out.

Check the amount of slack in the chain. If it is between 3% and 5% it is acceptable.

Tighten the clamping bolts.

Question 16:

Which procedure for removing a bearing is shown in FIGURE 1.4 below?

(See attached resource)

Attached Resource:

bebf0686-4356-4ce3-8ba4-181ea5ef9216.png

Your Answer:

Applying force to remove the shaft

Applying force to the bearing

Removing any rust from the shaft with emery paper

Measuring the position of the bearing

Question 17:

Which ONE of the following is an advantage of V-belts?

Your Answer:

Can be used on loose pulleys

May be used over long distances

Able to absorb shock loads

Operate at a high bearing pressure

Question 18:

What is the purpose of the linkage shown in FIGURE 1.5 below?

(See attached resource)

Attached Resource:

946a0b24-3e5a-4af3-a6c3-49eed2166822.png

Your Answer:

Converts rotary motion into oscillating motion

Converts oscillating motion into rotary motion

Converts reciprocating motion into rotary motion

Converts rotary motion into reciprocating motion

Question 19:

Determine the distance 'D' moved by the follower for one full revolution of the pear-shaped cam shown in FIGURE 1.6 below, given that d1 = 5 mm and d2 = 12 mm.

(See attached resource)

Attached Resource:

608c465b-0c3b-4b89-9780-96fbf2d2613e.png

Your Answer:

7 mm

17 mm

5 mm

12 mm

Question 20:

What is understood by the term pressure ratio in turbochargers?

Your Answer:

The pressure that the turbocharger generates in the intake manifold

The pressure that the turbocharger generates in the exhaust manifold

The inlet pressure compared to the outlet pressure

Decreased pressure in the exhaust manifold

Question 21:

The volumetric efficiency of a blower is the …

Your Answer:

ability to heat intake air.

ability to cool exhaust air.

ability to drive the blower.

ability to fill the cylinder with air above atmospheric pressure.

QUESTION 2: TOOLS AND EQUIPMENT

Marks: 20

Question 1:

When a dry compression test was conducted on cylinder number one of a four-stroke, four-cylinder, spark-ignition engine the result was very low compared to the engine specifications. State THREE possible causes of the low compression in cylinder number one.

Your Answer:

Question 2:

Define torsion.

Your Answer:

Question 3:

FIGURE 2.1 below indicates a multimeter that is used to test different electrical components and circuits. Label parts A–E on the multimeter.

(See attached resource)

Attached Resource:

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Your Answer:

Question 4:

The function of the cylinder leakage tester is to check whether the engine leaks gases from the cylinder during compression strokes. State THREE possible leakages during the cylinder leakage test and state the cause of each.

Your Answer:

Question 5:

What does the abbreviation MAGS/MIGS stand for in welding equipment?

Your Answer:

Question 6:

Name TWO gases that can be used in MAGS/MIGS welding.

Your Answer:

QUESTION 3: MATERIALS

Question 3.1

Marks: 2

Question 1:

Name ONE difference between non-ferrous metals and composites.

Your Answer:

Question 3.2 - FIGURE 3.1 below shows the results of a compressive strength test on two materials, A and B.

Marks: 3

Question 1:

Which of the materials, A or B, has the highest compressive strength?

(See attached resource)

Attached Resource:

d83d574d-3346-498a-8bbf-60b19ec937ab.png

Your Answer:

Question 2:

Give a reason for the answer to QUESTION 3.2.1 above.

Your Answer:

Question 3.3

Marks: 3

Question 1:

Name THREE main classes/groups of carbon steel.

Your Answer:

Question 3.4

Marks: 4

Question 1:

Name FOUR properties of carbon steel that will change when the carbon content is increased.

Your Answer:

Question 3.5 - Choosing the most suitable material for a particular product requires you to have good knowledge of materials. State TWO uses and TWO properties of the following engineering materials:

Marks: 4

Question 1:

State TWO uses and TWO properties of the following engineering materials: Duralumin

Your Answer:

Question 2:

State TWO uses and TWO properties of the following engineering materials: Polyvinyl chloride (PVC)

Your Answer:

QUESTION 4: SAFETY, TERMINOLOGY AND JOINING METHOD

Marks: 10

Question 1:

State THREE safety precautions to be observed when operating a beam bending tester.

Your Answer:

Question 2:

State THREE safety precautions to be observed when storing gas cylinders.

Your Answer:

Question 3:

Give TWO advantages of each of the following milling operations:

a) Upcut milling [2]

b) Down-cut milling [2]

Your Answer:

Question 4.4 - A gear with 63 teeth has to be machined on a milling machine. Use A = 60 or N = 60.

Marks: 9

Question 1:

Calculate the indexing required.

Your Answer:

Question 2:

Calculate the change gears required.

Your Answer:

Question 4.5

Marks: 7

Question 1:

Calculate the feed in millimetres per minute of an 80 mm diameter cutter with 14 teeth, operating at a cutter speed of 20 metres per minute and a feed of 0,08 mm per tooth.

Your Answer:

Question 4.6

Marks: 5

Question 1:

Mary is a quality controller who inspects welded joints on workpieces. She uses an ultrasonic test to determine whether the welds have any welding defects. Explain the principle of operation of the ultrasonic test on welded joints.

Your Answer:

Question 4.7 - State TWO possible causes and ONE preventive action for each of the following weld defects:

Marks: 6

Question 1:

Slag inclusion

Your Answer:

Question 2:

Undercutting

Your Answer:

Question 4.8

Marks: 4

Question 1:

Spur gear

Your Answer:

Question 2:

Groove

Your Answer:

Question 3:

Rack

Your Answer:

Question 4:

Blind hole

Your Answer:

Question 4.9 - FIGURE 4.1 below shows a dividing head of a milling machine. Label parts A–E.

Marks: 5

Question 1:

FIGURE 4.1 below shows a dividing head of a milling machine. Label parts A–E.

(See attached resource)

Attached Resource:

3bba01c0-839a-4acf-86fc-381d9114afb8.png

Your Answer:

Question 4.10

Marks: 4

Question 1:

State the TWO classes of milling cutters and give ONE example of each.

Your Answer:

QUESTION 5: MAINTENANCE AND TURBINES

Question 5.1 - Refer to attached resource

Marks: 15

Question 1:

Label parts A–F in the clutch and pressure-plate assembly.

(See attached resource)

Attached Resource:

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Your Answer:

Question 2:

State TWO functions of the clutch plate in this clutch and pressure- plate assembly.

Your Answer:

Question 3:

Name THREE causes of slip in this clutch and pressure-plate assembly.

Your Answer:

Question 4:

Name TWO types of clutches used in the engineering environment.

Your Answer:

Question 5.2

Marks: 3

Question 1:

State THREE functions of lubricating oil.

Your Answer:

Question 5.3

Marks: 3

Question 1:

State THREE guidelines for the maintenance of cutting fluid used in a lathe.

Your Answer:

Question 5.4 - The performance of smaller engines can be improved by using superchargers (FIGURE 5.2).

Marks: 13

Question 1:

Identify the type of supercharger shown in FIGURE 5.2.

(See attached resource)

Attached Resource:

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Your Answer:

Question 2:

Label parts A–D.

(See attached resource above)

Your Answer:

Question 3:

Explain the operation of the supercharger shown in FIGURE 5.2.

(See attached resource above)

Your Answer:

Question 4:

Name THREE advantages of superchargers.

Your Answer:

Question 5.5

Marks: 3

Question 1:

Name THREE classifications of steam turbines.

Your Answer:

Question 5.6

Marks: 3

Question 1:

State THREE advantages of gas turbines.

Your Answer:

QUESTION 6: FORCES, SYSTEMS AND CONTROL

Question 6.1 - A hydraulic system is being used to lift a machine part into position. The specifications of the system are diagrammatically presented in FIGURE 6.1 below.

Marks: 11

Question 1:

The fluid pressure in the hydraulic system when in equilibrium

(See attached resource)

Attached Resource:

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Your Answer:

Question 2:

The load that can be lifted by piston B when a force of 300 N is applied to piston A

(See attached resource above)

Your Answer:

Question 6.2

Marks: 9

Question 1:

A steel spoke of a bicycle wheel has a cross-sectional area of 2,2 mm2 and a length of 300 mm. The nut of the spoke is tightened until the length increases by 0,2 mm. Determine, by means of calculations, the tensile force in the spoke material. Take Young's elasticity modulus for the spoke material as 245 GPa.

Your Answer:

Question 6.3 - FIGURE 6.2 shows a belt-drive system. A pulley with a diameter of 0,25 m drives a driven pulley with a diameter of 0,35 m. The driver pulley rotates at 1 000 r/min. T1 = 200 N and T2 =90 N.

Marks: 9

Question 1:

Determine by means of calculations:

The rotation frequency of the driven pulley in r/min (revolutions per minute)

(See attached resource)

Attached Resource:

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Your Answer:

Question 2:

Calculate The power transmitted

(See attached resource above)

Your Answer:

Question 3:

The belt speed of the system in metres per second

Your Answer:

Question 6.4

Marks: 6

Question 1:

The rotation frequency of the output shaft if the electric motor rotates at 1 440 r/min.

(See attached resource)

Attached Resource:

edd88799-7e9b-475c-a3f3-7f69f0718e67.png

Your Answer:

Question 2:

Calculate The velocity ratio between the input and output shaft

(See attached resource above)

Your Answer:

Question 6.5 - A differential wheel-and-axle lifting machine is shown in FIGURE 6.4 below. A load of 2,4 kN is lifted when an effort of 400 N is applied. The diameters of the pulleys are 210 mm, 160 mm and 140 mm respectively.

Marks: 7

Question 1:

Determine by means of calculations:

The mechanical advantage

(See attached resource)

Attached Resource:

07088e5c-776a-4928-9f42-b6e6c55b84a1.png

Your Answer:

Question 2:

Calculate The velocity ratio

(See attached resource above)

Your Answer:

Question 3:

Calculate The mechanical efficiency of the machine

(See attached resource above)

Your Answer:

Question 6.6 - A single-plate friction clutch transmits a maximum torque of 336 Nm. The clutch plate has friction material on both sides with a friction co-efficient of 0,4. The total applied force on the friction surfaces is 3,5 kN.

Marks: 8

Question 1:

Determine by means of calculations:

Your Answer:

Question 2:

Calculate The power transmitted at 3 200 r/min

Your Answer: