6.1 State TWO methods to correct the static imbalance of a crankshaft - NSC Mechanical Technology Automotive - Question 6 - 2021 - Paper 1
Question 6
6.1 State TWO methods to correct the static imbalance of a crankshaft.
6.2 Define the following terms with regard to crankshaft balancing:
6.2.1 Dynamic balance
6... show full transcript
Worked Solution & Example Answer:6.1 State TWO methods to correct the static imbalance of a crankshaft - NSC Mechanical Technology Automotive - Question 6 - 2021 - Paper 1
Step 1
State TWO methods to correct the static imbalance of a crankshaft.
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Answer
Fitting balance mass pieces to the crank webs: This involves adding weighted pieces to specific points on the crankshaft to achieve balance.
Removing metal from the crank webs: This method reduces weight in specific areas, helping to balance the crankshaft.
Step 2
Define the following terms with regard to crankshaft balancing:
6.2.1 Dynamic balance
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Answer
Dynamic balancing refers to the process of ensuring that a crankshaft is balanced in all directions while it is rotating. This ensures that the rotating assembly does not create excessive vibrations, promoting smoother engine operation.
Step 3
6.2.2 Reciprocating mass
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Reciprocating mass is defined as the mass of the pistons, gudgeon pins, and the upper third of the connecting rod that moves up and down within a cylinder. The proper balancing of these masses is critical to minimize vibrations.
Step 4
Describe FOUR features that are built into an engine to improve engine balance.
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Answer
Lightweight connecting rods and pistons: Keeping these components light helps in achieving better static balance.
Carefully balanced flywheel: A balanced flywheel reduces vibrations during engine operation.
Counterweights on the crankshaft: These help to offset the forces produced by rotating components, leading to smoother operation.
Reconfigured firing order: Adjusting the firing order of the engine can help in reducing vibrations caused by uneven firing.
Step 5
Name TWO types of vibration dampers.
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Answer
Friction face-type damper: This type uses friction to reduce vibrations.
Combined rubber and friction disc damper: This damper combines rubber and friction elements to absorb and diminish engine vibrations.
Step 6
Identify the different types of cylinder arrangements, A, B and C, in FIGURE 6.5.
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A. Inline type / Straight arrangement
B. V-type
C. W-type / double-V type
Step 7
Draw a neatly labelled sketch to illustrate the position of the crank pins in a three-cylinder in-line engine.
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Answer
A sketch should be drawn showing three crank pins at equal intervals, usually at 120-degree angles from each other, clearly labelled.
Step 8
Name THREE types of superchargers used on an internal combustion engine.
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Answer
Roots supercharger
Twin-screw supercharger
Centrifugal supercharger
Step 9
State THREE advantages of using a turbocharger on an engine when compared to a normal induction engine.
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More power output: A turbocharger can enhance engine power output without increasing engine size.
Improved fuel consumption: It helps in improving fuel efficiency by making better use of exhaust gases.
Elimination of height effects: It reduces the impact of altitude on engine performance, providing consistent power.
Step 10
Label parts A–D in FIGURE 6.9.
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A. Intercooler/air cooler
B. Compressed air flow
C. Turbine/Turbine housing/Turbocharger
D. Exhaust gas flow/exhaust system/exhaust manifold
