Subtopic: Primary and secondary tillage implements
Question Statement:
In the disc plow blade geometric configuration illustrated in the schematic diagram below, which of the following statements regarding the disc angle ($\alpha$) and tilt angle ($\beta$) are CORRECT?
Options:
(A) The disc angle $\alpha$ is the angle made by the plane of the cutting edge of the disc with the direction of travel (typically $42^\circ - 45^\circ$)
(B) The tilt angle $\beta$ is the angle made by the plane of the cutting edge of the disc with the vertical line (typically $15^\circ - 25^\circ$)
(C) Increasing the tilt angle improves plow penetration in hard, dry soils
(D) Standard disc harrows also utilize a tilt angle adjustment
Answer Key:
A, B, C
Step-by-Step Solution & Explanation
1. Disc angle ($\alpha$) is defined in the horizontal plane between the plane of the cutting edge and the line of travel, standard range $42^\circ - 45^\circ$. (Statement A True)
2. Tilt angle ($\beta$) is defined in the vertical plane perpendicular to travel between the plane of the disc edge and the vertical, standard range $15^\circ - 25^\circ$. (Statement B True)
3. Tilt angle creates suction and upward soil lifting, facilitating penetration into hard crusted soil. (Statement C True)
4. Disc harrows have vertical gangs (tilt angle $\beta = 0^\circ$) and adjust only gang angle (disc angle). (Statement D False)