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Answer any three of the following: (i) Explain the difference between helical gears and spur gears - Leaving Cert Engineering - Question b - 2020
Question b
Answer any three of the following: (i) Explain the difference between helical gears and spur gears. (ii) Give two advantages of the use of roller bearings in machi... show full transcript
Worked Solution & Example Answer:Answer any three of the following: (i) Explain the difference between helical gears and spur gears - Leaving Cert Engineering - Question b - 2020
Step 1
Explain the difference between helical gears and spur gears.
Answer
Helical gears are a refinement over straight spur gears, featuring teeth that are not parallel to the axis of rotation; they are set at an angle. This design allows helical gears to engage more gradually than spur gears, resulting in smoother operation and less noise. In contrast, spur gears have teeth that run straight and are parallel to the axis of rotation, causing a more sudden engagement.
Step 2
Give two advantages of the use of roller bearings in machinery.
Answer
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Reduced Friction: Roller bearings provide a smooth interface, significantly reducing friction between moving parts, which enhances efficiency.
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Reliability: They are designed for high load capacities and are more durable than other types, leading to increased reliability and longevity of machinery.
Step 3
Describe how the camshaft opens the valves in a four-stroke engine.
Answer
The camshaft is equipped with 'egg' shaped cams which rotate and press against the valve tappet, causing the valves to open as the cam turns. When the cam rises, it pushes the valve open against its spring, allowing air and fuel into the cylinder. When the cam rotates further, the spring closes the valve once the cam has passed its high point.