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:
In combine harvesters, mechanical kernel damage (micro-cracks and pericarp breakage) increases dramatically when the peripheral velocity of the threshing cylinder exceeds approximately:
Options:
(A) $12\text{ m/s}$
(B) $32\text{ m/s}$
(C) $55\text{ m/s}$
(D) $75\text{ m/s}$
Answer Key:
B
Step-by-Step Solution & Explanation
- Extensive empirical testing of threshing dynamics shows that grain impact damage remains below $2\text{--}3\%$ when peripheral cylinder speed is maintained under $28\text{--}30\text{ m/s}$.
- Beyond $32\text{ m/s}$, impact stresses exceed the rupture limit of cereal endosperm, causing rapid surge in broken grains and reduced seed germination viability.