Theory of Machine
The Ackerman steering gear mechanism is preferred to the Davis steering gear mechanism, because

The Ackerman steering gear consists of turning pairs
Whole of the mechanism in the Ackerman steering gear is on the back of the front wheels
The Ackerman steering gear is most economical
Both (A) and (B)

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Theory of Machine
Two pulleys of radii r₁ and r₂ and at distance x apart are connected by means of a cross belt drive. The length of the belt is

π (r₁ - r₂) + [(r₁ + r₂)²/x] + 2x
π (r₁ - r₂) + [(r₁ - r₂)²/x] + 2x
π (r₁ + r₂) + [(r₁ + r₂)²/x] + 2x
π (r₁ + r₂) + [(r₁ - r₂)²/x] + 2x

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