Question 1
- The sketch in fig. 1 shows the operation of a compression-ignition engine.
- What type of injector is shown in the engine?
- What type of injection system is used by the engine?
- Explain why the combustion chamber is shaped as shown in the sketch.
- Describe how combustion takes place in compression- ignition engine.
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- What is the main function of automobile steering ball joint?
- Modern cars are designed with allowance for varying lengths of wishbone arms. What is the purpose of such variation?
Observation
Candidates’ responses to 1(a)(iv) and 1(b)(i) were okay. Their responses to other parts of this question were inadequate. The solution to the poorly answered part of the question is given below
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The Type of Injector Shown in the Engine
Multi-hole injector
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The Type of Injection System Used by the Engine
Direct Injection Sysytem
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The Reason Why the Combustion Chamber is Shaped As Shown
The combustion chamber is shaped as such in order to cause the air to move violently and then mix with the sprayed fuel which is broken into minute particles.
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The Type of Injector Shown in the Engine
- ii.
The Purpose of In-built Variation of the Length of Wishbone
Arms
The variation is done in order to reduce tyre wear.