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3.1 Name TWO devices that are used to test the hardness of a metal - NSC Mechanical Technology Fitting and Machining - Question 3 - 2017 - Paper 1
Question 3
3.1 Name TWO devices that are used to test the hardness of a metal. 3.2 Give THREE reasons for using a compression tester on an engine. 3.3 State the function of a... show full transcript
Worked Solution & Example Answer:3.1 Name TWO devices that are used to test the hardness of a metal - NSC Mechanical Technology Fitting and Machining - Question 3 - 2017 - Paper 1
Step 1
Name TWO devices that are used to test the hardness of a metal.
Answer
The two devices that can be used to test the hardness of a metal are:
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Brinell Hardness Tester - This tester uses a hard steel or carbide ball as an indenter to determine the hardness based on the size of the indentation.
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Rockwell Hardness Tester - This device measures the depth of penetration of an indenter under a large load compared to the penetration made by a preload.
Step 2
Give THREE reasons for using a compression tester on an engine.
Answer
Three reasons for using a compression tester on an engine include:
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Check for Worn Cylinders - It helps in identifying wear in the cylinders by measuring compression levels.
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Inspect Valve Sealing - The tester can determine if valves are sealing properly by comparing compression in different cylinders.
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Diagnose Engine Performance Issues - Low compression readings can indicate potential problems, such as piston ring failure or head gasket leaks.
Step 3
Step 4
Give TWO reasons for a high CO reading.
Answer
Two reasons for a high CO (Carbon Monoxide) reading in exhaust gases can be:
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Rich Mixture Setting - An overly rich fuel-air mixture can lead to incomplete combustion, causing an increase in CO emissions.
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Incorrect Idle Speed - If the idle speed of the engine is too low, it can result in poor combustion efficiency and subsequently higher CO levels.
Step 5
List THREE operating rules when using a multi meter.
Answer
Three operating rules when using a multi meter are:
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Check Connections - Ensure that the measuring leads are inserted correctly into the appropriate sockets for the measurement you wish to take.
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Select Proper Function - Set the meter to the correct measurement function (voltage, current, or resistance) before starting your test.
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Start with the Highest Range - If uncertain about the output, begin on the highest range setting and then adjust downwards for more precise readings.