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:
Which of the following statements comparing axial-flow (rotary) and conventional cross-flow (tangential) threshing cylinders in combine harvesters is/are correct?
Options:
(A) In axial-flow combines, crop spirals repeatedly around the rotor along its longitudinal axis, subjecting crop to multiple gentle rubbing actions.
(B) Axial-flow threshing systems generally produce lower mechanical grain damage and less seed coat cracking compared to high-impact tangential rasp-bar cylinders.
(C) Conventional cross-flow cylinders thresh the entire crop during a single short arc of contact (typically $100^\circ - 120^\circ$) under the concave.
(D) Axial-flow combines completely eliminate the need for a cleaning shoe and blower fan.
Answer Key:
A, B, C
Step-by-Step Solution & Explanation
• Axial-flow rotors transport crop axially while rotating it through multiple helical passes, increasing separation area with lower impact severity (A and B are correct).
• Cross-flow cylinders subject crop to severe impact in a single wrap of the concave (C is correct).
• Axial combines still require reciprocating cleaning shoes, chaffer sieves, and fan assemblies for pneumatic separation (D is false).