All India Mechanical Engineering Group

Understanding the Problem
To calculate the time required to fill the mould cavity, we need to determine the flow rate of the molten material through the downsprue and runner system.
Given Data:
- Length of downsprue = 20 cm
- Cross-sectional area of downsprue = 1 cm²
- Volume of mould cavity = 1000 cm³
Flow Rate Calculation
1. Velocity of ... moreFluid in Downsprue:
- The velocity (v) can be calculated using the formula:
v = √(2gh)
- Here, 'g' is the acceleration due to gravity (approximately 980 cm/s²), and 'h' is the height of molten metal in the downsprue, which we can assume to be equal to its length for simplicity, hence h = 20 cm.
2. Calculate Velocity:
- v = √(2 * 980 * 20) = √(39200) ≈ 198.0 cm/s
3. Flow Rate (Q):
- Q = A * v
- Where A is the cross-sectional area of the downsprue.
- Q = 1 cm² * 198.0 cm/s = 198.0 cm³/s
Time to Fill the Mould Cavity
4. Time (t):
- Time required to fill the mould cavity can be calculated using:
t = Volume / Flow Rate
- t = 1000 cm³ / 198.0 cm³/s ≈ 5.05 seconds
Conclusion
The calculated time required to fill the mould cavity is approximately 5.05 seconds, which corresponds to option B. This result is consistent with the principles of fluid dynamics in casting processes and highlights the importance of understanding flow rates in mould filling operations.

Understanding Oldham Couplings
Oldham couplings are mechanical devices used to connect two shafts that are not perfectly aligned. They are designed to transmit torque while accommodating misalignment and providing some degree of flexibility.
Correct Statements
The correct statements regarding Oldham couplings are:
I. Torsional load is transferred along shaft ax... moreis.
- This statement is true. Oldham couplings are designed to transfer torque (torsional load) between the connected shafts along their axis.
II. A velocity ratio of 1:2 between shafts is obtained without using gears.
- This statement is false. Oldham couplings do not change the speed or provide a velocity ratio; they merely transmit motion and torque at the same speed between shafts.
III. Bending load is transferred transverse to shaft axis.
- This statement is false. Oldham couplings do not effectively transfer bending loads; they are primarily designed to handle torsional loads.
IV. Rotation is transferred along shaft axis.
- This statement is true. Oldham couplings facilitate the transfer of rotational motion along the axis of the shafts they connect.
Conclusion
Based on the evaluation of the statements:
- The correct answer is option 'B', which includes statements I and IV.
- These statements accurately reflect the operational principles of Oldham couplings, highlighting their role in torque transfer and alignment flexibility while confirming that they do not provide speed changes or handle bending loads effectively.