ROTARY TRANSMISSION

Rotary transmission system put two rotating elements into contact.These mechanisms have two purposes:

v  Transferring rotary force from an input location to another location.

v  Changing the rotary speed by using rotating elements of different sizes.

      This images represented: Friction wheels, pulleys with belts, interlocking gears and sprockes with chains.All of these mechanisms keep the same ratios, but each one offers a diferent advantage.

 CHANGES IN SPEED

If we want to increase the speed of a rotary system, we must transmit motion from a larger element to a smaller element. However, when we increase the speed we also decrease the rotary  force,or  torque.

The opposite is true if we want to decrease the speed of a rotary system. We mst transmit motion from a smaller element to a larger element. At the same time, we can also increase the torque. If the input and output elements are the same size, the rotary speed remains constant. The rotary force will also remain constant.

SPEED RATIOS

The relationship between the speeds of the two wheels is inversely proportional to their sizes.

 (N2/N1=D1/D2)

This relationship is called the ratio of the tansmission, where N is the speed of rotation and D is the diameter of the Wheel.

If we want  to calculate the size ratio of wheels or  pulleys, we can compare their diameter, radius or circumference. In the case of gears, we compare the number of cogs or teth that each gear has.

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