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Sunday, 3 December 2017

Gears

gear introduction


          A Gear also reffered to as "Cog wheel", is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part so as to trasmit torque from one part of the machine to another.
Image source: Onlinelabels.com


          In our daily life in most machines we tend to use gears. Gears form vital components of machanisms in several machines such as toys, automobiles, watches, rolling mills etc., With a little force input they turnout nice output or force. Two or additional gears engaged in tandum transfer motion from one gear to another and will produce a mechanical advantage through a gear ratio and therefore is also considered a simple machine. Different gear sizes and shapes will modify the speed, magnitude and direction of rotation of a power source (between an input and output shaft). The foremost common scenario is for a gear to mesh with another gear, however a gear can even mesh a non-rotating toothed part, referred to as rack, there by producing translation rather than rotation.
          The gears in a transmission are similar to the wheels in a cross belt pulley. When compared to the belt pully system, advantage of gears is that the teeth of a gear prevent slipping
          We connect gears one another, sometimes they vary in sizes and number of teeth. When we connect two gears of unequal number of teeth a mechanical advantage is produced, with both the rotational speeds and torques.

Increase in speed: Imagine that we are connecting one gear with another, with the first gear having more teeth compare to second gear. In this case the second gear makes faster rotations when compared to first gear. As a reasult the power in the both gears remains same but torque of the second gear decreases.

Increase in torque: Similarly imagine that we are connecting two gears where he first one having less teeth compared to the second one. In this case, the second gear makes slower rotations compared to first one. As a result the torque in the second gear increases but the power in both gears remains same.

They can be applied for two shafts which are :-
  • Parallel
  • Collinear
  • Perpendicular and intersecting
  • Perpendicular and non-intersection
  • Inclined at an arbitrary angle
Use of Gears :-
          1. Direction of rotation is reversed
      2. By meshing uneven number of toothed gears we are able to increase or decrease the spped of rotation
          3. To move rotational motion to a distinct axis
          4. To keep the rotation of two axis synchronised
Image Source: www.robotpark.com

Advantages of Teeth :-
          1. They prevent slippage between the gears - therefore axles connected by gears are always synchronised precisely with each other.
          2. They make it possible to determine precise gear ratios - you just count the number of teeth in the two gears and divide larger with smaller. So if one gear has 75 teeth and another has 15, the gear ratio when these two gears are connected together is 5:1.
          3. They are created in such a way that slight imperfections within the actual diameter and circumference of two gears do not matter. Eventhough the diameters vary a little, the gear ration is controlled by the quantity of teeth.

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