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The graphic on the right shows a child's toy train - Leaving Cert DCG - Question C-4 - 2022
Question C-4
The graphic on the right shows a child's toy train. The toy train has a cam attached to the front axle which causes the smoke stack to rise and fall, through an inl... show full transcript
Worked Solution & Example Answer:The graphic on the right shows a child's toy train - Leaving Cert DCG - Question C-4 - 2022
Step 1
Draw the displacement diagram
Answer
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Locate cam displacement at 0°, 180°, 270°, and 360°:
- The displacement at 0° is 0 mm, at 180° is 42 mm (maximum height), at 270° returns to 0 mm, and at 360° falls to the defined height.
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Construct to determine U.A.R. curve:
- Using a ruler and protractor, plot the U.A.R. curve, ensuring it rises uniformly to 42 mm, then drops back smoothly.
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Draw U.A.R. curve:
- Following the plotted points, connect with a smooth curve indicating the motion, showing a gradual increase and decrease in height.
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Draw 'Tail' 180° to 270° on the displacement diagram:
- This segment shows a smooth transition from maximum height back to the height of 0 mm accordingly.
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Establish eccentric centre of cam profile:
- Given that the nearest roller center to cam center is 40 mm, mark this on the diagram.
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Draw 30° divisions through cam centre:
- This represents important segments where the cam interacts with the roller follower.
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Transfer this displacement diagram to cam profile:
- Sketch the cam profile respecting the roller locations and transitions based on displacement values.
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Draw lines on 30° divisions lines:
- Ensure clear marking of these lines on the cam profile for reference.
Step 2
Draw the diagram as given (including AB, BC, CD and Crushing Platform)
Answer
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Draw a line diagram of mechanism AB and BC:
- Start by drawing line AB at 30° angle from vertical. Extend line BC to represent the connection to the fixed point.
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Project points C and D:
- Identify points C and D where the rotating arms connect. Ensure they are accurately placed based on the lengths provided.
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Depict the Crushing Platform:
- Draw the platform horizontally at the correct height based on distance from point D.
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Mark all relevant points clearly for clarity.
- Include annotations for each line and angle as necessary to convey full structural intentions.
Step 3
Draw Crushing Platform in 40 mm crushing position
Answer
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Indicate the new position of the crushing platform when the can is at 40 mm:
- Adjust the horizontal level of the crushing platform to reflect the crushed height of 40 mm.
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Align all joints accordingly:
- Ensure all lines (AB and BC) reflect their connections with the new position of the crushing platform.
Step 4
Establish position of D when Crushing Platform is in 40 mm position
Answer
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Locate point D's position given the new platform height:
- Draw a vertical line from the initial platform height down to where it intersects with line CD.
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Verify the joint movement of point D is consistent with the vertical constraint.
Step 5
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Step 7