Farm Machinery and Power Engineering- ICAR JRF/SRF 2024

• Shape Classification of Potato Tubers:
• In farm machinery design (specifically potato diggers, elevator chains, and graders), tuber shape is characterized using the Index of Tuber Shape ($I_s$):

where $L$ is length, $W$ is width, and $T$ is thickness.

• Shape Categories:
• Round tubers: $I_s \lt 150$
• Oval / Elliptical tubers: $150 \le I_s \lt 240$
• Long tubers: $240 \le I_s \le 340$
• Very long tubers: $I_s \gt 340$
• Conclusion: An index of 240 to 340 indicates Long tubers (Option 3).

Correct option: (3) Long

• Delivery Rate of Agricultural Dusters:
• Standard Specifications (IS 5133 / IS 8758): For manually operated rotary and knapsack powder dusters, the maximum delivery setting must ensure uniform, rapid chemical application across target crop canopies.
• Minimum Output: The delivery rate at the maximum discharge opening setting shall not be less than $150\text{ g/min}$ ($150\text{ g}\cdot\text{min}^{-1}$) when operating at rated cranking speed (approx. 30–35 rpm of crank handle yielding 2500–3000 rpm of impeller).
• Conclusion: 150 g.min$^{-1}$ (Option 2).

Correct option: (2) 150 g.min+

• Electromagnetic Frequency Domain Transducers:
• Operating Principle: Electromagnetic pulse pick-ups (variable reluctance sensors, magnetic gear tooth sensors, or Hall effect frequency sensors) generate electrical voltage pulses as ferromagnetic gear teeth pass through a localized magnetic field.
• Measured Parameter: The frequency ($f$) of the output pulse train is directly proportional to rotational speed:

where $Z$ is the number of teeth or poles. Thus, it operates in the frequency domain to measure shaft rotational speed.

• Conclusion: Speed (Option 3).

Correct option: (3) Speed