6.1 What do you understand by static balancing of a crankshaft?
6.2 Identify the cylinder layouts as illustrated in FIGURES 6.2.1 and 6.2.2 below - NSC Mechanical Technology Automotive - Question 6 - 2018 - Paper 1
Question 6
6.1 What do you understand by static balancing of a crankshaft?
6.2 Identify the cylinder layouts as illustrated in FIGURES 6.2.1 and 6.2.2 below.
6.3 Explain ... show full transcript
Worked Solution & Example Answer:6.1 What do you understand by static balancing of a crankshaft?
6.2 Identify the cylinder layouts as illustrated in FIGURES 6.2.1 and 6.2.2 below - NSC Mechanical Technology Automotive - Question 6 - 2018 - Paper 1
Step 1
What do you understand by static balancing of a crankshaft?
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Answer
Static balancing of a crankshaft refers to the condition where the mass of the crankshaft is evenly distributed around its center of rotation. When a crankshaft is static, it does not rotate, and thus, any mass imbalance in any direction will lead to vibrations when in motion. Proper static balancing is crucial for reducing wear and tear on engine components and ensuring smooth operation.
Step 2
Identify the cylinder layouts as illustrated in FIGURES 6.2.1 and 6.2.2 below.
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Explain how you will determine the firing order of a four-cylinder petrol engine if it is not marked on the crankshaft pulley and the manual is not available.
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Answer
To determine the firing order of a four-cylinder petrol engine, one can follow these steps:
Remove the tappet cover and observe which valves are intake and which are exhaust.
Rotate the engine in its normal direction of rotation.
Watch the movement of the valves to see which ones open during the intake and exhaust strokes.
The sequence of strokes will give the firing order.
Power strokes occur in the order of cylinder identification during the rotation.
Step 4
State the firing order of the following types of engines:
4-cylinder in-line engine
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The firing order for a four-cylinder in-line engine is typically one of the following sequences:
1-3-4-2
1-2-4-3
Step 5
State the firing order of the following types of engines:
V6-cylinder engine
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The firing order for a V6-cylinder engine can be as follows:
1-4-2-5-3-6
1-2-3-4-5-6
1-4-5-2-6-3
Step 6
Label parts A–G.
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A - Compressor air inlet
B - Turbine housing
C - Turbine exhaust gas outlet
D - Turbine wheel
E - Turbine exhaust gas inlet
F - Compressed air outlet
G - Compressor wheel
Step 7
State TWO advantages of the turbocharger.
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Answer
More power/speed is obtained from an engine with the same capacity.
Improved fuel consumption due to better efficiency.
Step 8
Explain the following terms:
Boost
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Boost refers to the increase in manifold pressure generated by the turbocharger in the intake manifold, exceeding the normal atmospheric pressure, which allows for increased engine power and efficiency.
Step 9
Explain the following terms:
Turbo lag
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Turbo lag is the delay experienced between pressing the accelerator and observing increased power output from the turbocharger. It occurs as the time it takes for the turbocharger to spool up and produce increased boost pressure.
Step 10
What is the purpose of the waste gate in the turbocharger?
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The waste gate diverts exhaust gases away from the turbine wheel to regulate turbine speed and consequently boost pressure. This helps to prevent overboosting and potential engine damage.
Step 11
What is the purpose of an oil cooler fitted to a turbocharged engine?
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An oil cooler prevents overheating by cooling the oil that lubricates the turbocharger bearings, thereby extending the reliability and performance of the turbocharger.
