Subtopic: Functional requirements, principles of working, construction and operation of manual, animal, tractor and renewable energy operated equipment for tillage, sowing, planting, fertilizer application, inter-cultivation, spraying, mowing, chaff cutting, harvesting and threshing
Question Statement:
The metering mechanism of a seed drill is driven by the ground wheels at a velocity ratio of 1:2. When forward speed of the seed drill is increased from 3.0 to 3.45 km h⁻¹, the seed rate would
Options:
(A) increase by 15%
(B) decrease by 13%
(C) decrease by 15%
(D) remain the same
Official Answer Key:
D
Step-by-Step Solution & Explanation
Since the metering mechanism is ground-wheel driven, the number of rotations of the metering shaft (and hence seeds dropped) per unit distance travelled is fixed by the gear/velocity ratio, independent of forward speed — both seed drop rate and ground speed scale together. Seed rate is normally expressed per unit area (kg/ha or seeds/ha), which depends only on the fixed metering-to-wheel ratio and row spacing, not on how fast the drill is pulled. So increasing forward speed changes the time taken to cover the field but not the seed rate per hectare — it remains the same, option (D). This is the key advantage of ground-wheel-driven (as opposed to engine/PTO-driven) metering: rate is self-compensating for speed changes.
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