A trailed tandem disc harrow has four gangs with 6 discs per gang, making a total of 24 discs of $50\text{ cm}$ diameter spaced $22\text{ cm}$ apart. The gang angle is $18^\circ$. Calculate the total effective working width of the harrow in $\text{meters}$ assuming total working width equals twice the single gang effective width.
Answer Key:
2.51
Step-by-Step Solution & Explanation
For one gang with 6 discs (5 intervals of $22\text{ cm}$ plus one disc cut allowance, approx $6 \times s \cos\theta$):
Width of cut per gang pair span:
$W_{\text{half}} = (6 \times 0.22) \times \cos(18^\circ) = 1.32 \times 0.95106 = 1.255\text{ m}$
Total working width for tandem double action:
$W = 2 \times 1.255 = 2.51\text{ m}$