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

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

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Theory of Machine
Crowning on pulleys helps

For automatic adjustment of belt position so that belt runs centrally
In decreasing the slip of the belt
Increase belt and pulley life
In increasing velocity ratio

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