• Balancing of Mower Pitman Drives:
• Assertion (A): The rotating counterweight commonly provided on the flywheel of a mower pitman drive does not give complete balancing. $\implies$ True.
• rotating counterweight generates a centrifugal force in all radial directions ($360^\circ$), whereas the knife reciprocates linearly along a single horizontal axis; balancing the horizontal inertia force introduces an unbalanced vertical force.
• Reason (R): Inertia force of the knife varies as the square of crank speed and as the first power of stroke. $\implies$ True.
• For simple harmonic motion, maximum inertia force is $F_i = m \omega^2 r = m \omega^2 (S/2) \propto N^2 \cdot S$.
• Relationship: Reason (R) defines the magnitude of reciprocating inertia, while Assertion (A) stems from the directional mismatch between rotating counterweights and linear reciprocation.
• Conclusion: Both (A) and (R) are true but (R) is NOT the correct explanation of (A) (Option 2).

Correct option: (2) Both (A) and (R) are true but (R) is NOT the correct explanation of (A).