Hello,
How are you, and how did your day go? I hope we all have been doing well. As for me I am still annoyed at my school for not making our results In time for the NYSC batch A mobilization. So, they are officially delaying another seven months of my life.

Many already know where I carried out my industrial attachment at an internal combustion engine work shop. I could not find a big company to give me a chance, so I said to myself why not?


During the early days of my industrial attachment at this gentleman’s workshop I saw many things that marveled me the tools, crank shafts, pistons, connecting rods and so many other things. But one this one really marveled me the way it looked was some how like it had teeth’s and was dangerously ready to chop off anything that comes it way. 


I later asked after trying to lift this thing off the ground it was very heavy I almost had my back stretched out. I called another apprentice to ask what this was and how was it used in the engine. The young apprentice came he told me it was a fly wheel and it is used at the end of the crankshaft.


I stared for so long looking at this component part not satisfied at the answer I got why was it this heavy and why does it have so many teeth’s what does it bite these were the questions that filled my head as I could not provide answers to any.


Then the day came when we decided to use this component during the coupling of an engine. It took too hefty men to carry the flywheel as it was attached to the end of the crankshaft and as for the teeth, turns out the little teeth were not as sharp and beautiful as the ones found on smaller circular wheels which were used later but arranging several sizes such that their teeth fit and sits directly in the spaces of the teeth of another type. These beautiful parts are called mechanical gears.

## <center>What are mechanical gears?</center>


<div class="pull-left"><center><img src="https://steemitimages.com/DQmZMsZqXr5wRnfmmqrdNizPNnEp6KHVA5o9Zw2gVWuXbFN/download%20.jpeg"/><br/><em><sup><sup><a href="https://commons.wikimedia.org/wiki/File:Gears_(20437315996.jpg">
Gears: img from Wikimedia under CCO license</a></sup></sup></em></center></div>



A mechanical gear is also called a cogwheel. I guess we all know what a wheel does. Okay, it rotates so it’s a rotating wheel which are meshed together with other cogwheel or teeth.


A mechanical gear is therefore a rotating element part with cogs or teeth which attach or mesh together with another gear part for the main purpose of transmitting power, toque or force. it performs just like the belt drive, but it is very much different.


They can as well change the speed and direction of power. The gears can be referred to as a machine on it own as they are special and could be complicated on their own. They are known for their accuracy in velocity ratio, their transmission in high toque, high efficiency and reliability.


Motorcycles, bicycles, generators and several engines use gears for power transmission. These gears need much lubrication. Which is why many don’t like it but it is really cool and quite expensive too.

<p><img src="https://steemitimages.com/DQmS9w2nNjPbewDArfV2f4x7VJvTgSRBK9mjXwPyKCfXFxH/707932.png"></p>



## <center>Classification of gears</center>



There are different ways by which the mechanical gears are classified, and each classification have several sub headings so I might be brief to keep this from becoming so lengthy.

* Gear classification according to position of axes of shaft. 
* Gear classification according to peripheral velocity of gears. 
* Gear classification according to the gearing type. 
* Gear classification according to position of teeth on gear surface.

 
<br>
<center>
https://steemitimages.com/DQmVELqFozeNKuytWHQkaBJnY5S4pwEW6rbowRhwSRST3MP/organo.JPG
<sup>organogram classification by @adetola</sup>
</center>


<p><img src="https://steemitimages.com/DQmS9w2nNjPbewDArfV2f4x7VJvTgSRBK9mjXwPyKCfXFxH/707932.png"></p>


### <center>Gear classification according to position of shafts axes</center>




These classifications are based on the position of axes of shafts. And are further classified into
Parallel, intersecting and, non-parallel and non-intersecting shafts. 


### 1. Parallel shaft gears
Parallel shaft bearings are the same as the rolling of two cylinders and there are some gear types under this classification include;


#### Spur gears 
These are the most common type of gears you and I find around us they are simple with their cogs parallel to the gear axis. Contact of the cogs happens over the whole width along a line parallel to their axes of rotation. As this gear rotates their line of contact goes on shifting parallel to their shaft.

<br>
<center>
https://steemitimages.com/DQmNPK85fCjyKeVgKJ2HsX6QaHR9tcpswbACg8cspPGaS8q/2000px-Spur_Gear_12mm%2C_18t.svg%20.png
[<sup>spur gears image from Wikipedia under CCO license</sup>](https://en.wikipedia.org/wiki/Gear)
</center>


#### Helical gears
Helical gears have their cogs or teeth in helix instead of straight across the gear parallel to the axis. The mating gears also have the same helix angle as the parent gear but are in opposite direction so that both gears can mate properly. As this gear rotates, the contact between them shifts in volute across the teeth.


<br>
<center>
https://steemitimages.com/DQmNbevckjW49MnXvKKoek2iytiBoGcLWjEuaB9mN6Zi6tz/Helical_Gear_Shaper_Cutters.jpg
[<sup>helical gears image from Wikimedia under CCO license</sup>](https://commons.wikimedia.org/wiki/File:Helical_Gear_Shaper_Cutters.jpg)
</center>

#### Herringbone gears
They a form of helical gears but a doubled type of helical gears, they are composed of two helical gears but with opposite helix angles up to 45 degrees.


<br>
https://steemitimages.com/DQmSzpMnGeWy4KbWZGoMy6wcSSLatKxaLnAURu9NX7xa94E/Herringbone_double-helical_bevel_gears%2C_Citroens_patent_Autocar_Handbook%2C_Ninth_edition.jpg

[<sup>herringbone gears image from Wikimedia under CCO license</sup>](https://commons.wikimedia.org/wiki/File:Herringbone_double-helical_bevel_gears,_Citroens_patent_Autocar_Handbook,_Ninth_edition.jpg)




### 2. Intersecting shaft gears
Let’s take a look at the intersecting shafts like two cones which are placed side by side and rolling together this is how the intersecting gears work.  There are several gears under this classification some of which are;


#### Straight bevel gears
The straight bevel gears have straight cogs, which are radial to the point of intersection of shaft axes and could vary in different cross sections through the length. Straight bevel gears are like the modifications to straight spur gears where cogs are conical instead of parallel.


#### Spiral bevel gears
This type of gears is made with their teeth at an angle which is inclined to the face of the bevel. They can be called helical bevels too.
<br>
<center>
https://steemitimages.com/DQmXKQZnvdrdTebNS4SzpSwHLApvAXajG6gXcuXiG9RPFm6/download%20.jpeg
[<sup>spiral bevel gears image from pixabay under CCO license</sup>](https://pixabay.com/en/gears-spiral-bevel-gears-bevel-gear-67862/)
</center>

### 3. Non-parallel and non-intersecting shafts
several types of gears under this classification includes
gears for skew shafts, hyperploid gears and worm gears.
 
<br>
<center>
https://steemitimages.com/DQmNR7AZ3DoGDb7UD4surdyKHDedBWeUCVcorHF1iFzAnjX/download%20.jpeg
[<sup>worm gears image from Wikipedia under CCO license</sup>](https://en.wikipedia.org/wiki/Gear)
</center>


<p><img src="https://steemitimages.com/DQmS9w2nNjPbewDArfV2f4x7VJvTgSRBK9mjXwPyKCfXFxH/707932.png"></p>


## <center>Gear classification according to gearing type </center>




There are external gears, internal and rack and pinion all classified under this type of gear classification.


### The external and internal gear
The external gears are those type of gears which have their cogs formed on the outside surface of a cylinder or cone just like the spur gear, helical gear and so on 
While the internal gear is a type of gear in which the cogs are formed on the inner surface of a cylinder or cone.
<br>
<center>
https://steemitimages.com/DQmPo4iXfHVEmyWVLynFH5KnqcwFgvk2GdKWbDgRkiEqP38/Bicycle_hub_gear.png
[<sup>external and internal gears image from Wikipedia under CCO license</sup>](https://en.wikipedia.org/wiki/Hub_gear)
</center>

### Rack and pinion gears 
They are like the spur gear with an infinite pitch radius with their axis of rotation places at infinity parallel to that of pinion. It is therefore the pinion that rotates while the rack translates.

<br>
<center>
https://steemitimages.com/DQmdeGHTKqByk4B4Ze3yt6tz22kxQ3GQ2md5VT88DqKhiqy/pinion-365523_960_720.jpg
[<sup>pinion gears image from pixabay under CCO license</sup>](https://pixabay.com/en/pinion-gear-man-passing-time-time-365523/)
</center>


<p><img src="https://steemitimages.com/DQmS9w2nNjPbewDArfV2f4x7VJvTgSRBK9mjXwPyKCfXFxH/707932.png"></p>


## <center>Gear classification according to peripheral velocity of gears</center>


According to this type of classification, gears are of three types which are high velocity, low Velocity and medium velocity gears. 
High velocity gears are gears which are applied in velocities more than 15m/s while medium velocity gears have their applications between 3-25m/s and the low velocities are applied where little speed is needed less than 3m/s.


<p><img src="https://steemitimages.com/DQmS9w2nNjPbewDArfV2f4x7VJvTgSRBK9mjXwPyKCfXFxH/707932.png"></p>

## <center>Gear classification according to position of teeth on gear surface</center>


These classifications is based on how their cogs look like and they are of three types which are straight, inclined and curved.
These can be seen from the way they heir cogs are the spur gears foe instance have their cogs straight while the helical gears have their cogs curved the spiral bevel gears are inclined.

<p><img src="https://steemitimages.com/DQmS9w2nNjPbewDArfV2f4x7VJvTgSRBK9mjXwPyKCfXFxH/707932.png"></p>

## Gear applications


There are several applications if gear drives and the way they could be applied or have been applied in the engineering world from the automobile transmission to the internal combustion engines , not forgetting the wind turbine application or power generation, robotics food processing, packaging machines, material handling, wood and glass processing to medicine or medical field there are so many I could keep listing them but this is becoming lengthy lol.

<p><img src="https://steemitimages.com/DQmS9w2nNjPbewDArfV2f4x7VJvTgSRBK9mjXwPyKCfXFxH/707932.png"></p>

## What is responsible for gear damage?


As powerful as your gear can be don’t get it twisted it could be damaged if not taken good care of and here are some of the damages that could happen.

Bending, your gear cogs could bend and break off if the total load or repetitive load acting is greater than the strength of the gear. Several surface contact stresses could lead to fatigue failure hence pitting. 

Excessive heat from excessive surface pressure may lead to scoring in gears or simply lack of enough lubrication. Abrasive wear may occur due to dirt or particles in lubricants or on the surface of the gear.

Corrosion the master of all could totally damage your gears all it needs is water and air so prevent water from coming in contact with your lubricants.

<p><img src="https://steemitimages.com/DQmS9w2nNjPbewDArfV2f4x7VJvTgSRBK9mjXwPyKCfXFxH/707932.png"></p>


## Conclusion



The gear drives are a wonderful improvement with their teeth’s and cogs they have high velocity ratio and can transmit a more powerful torque. The gear drives are used for short distances and with several classifications and types their design may vary according to their use. 
The gear drives have many industrial use and application in the world and could easily be damaged as easy as dirt or water in lubricants.

Gears are known to improve speed and change direction of torque. Gears are made by using milling machine they are different from the fly wheel even though some flywheels could look like gears from far away but don’t be confused gear teeth’s are sharper and different from the fly wheel even with their weights you could tell the difference between both. 

Do you know what milling machines are? They are the machines used to make the gear drives don’t for get that I might come back for another episode of this exciting topic.

<p><img src="https://steemitimages.com/DQmS9w2nNjPbewDArfV2f4x7VJvTgSRBK9mjXwPyKCfXFxH/707932.png"></p>

## References


For further reading please visit any of these links or get the following books
A text book of machine design by R.S. Khurmi and J.K. Gupta|[gears wiki](https://en.wikipedia.org/wiki/Gear)|[introduction to gears]( https://khkgears.net/new/gear_knowledge/introduction_to_gears/types_of_gears.html)|[explain that stuff gears](http://www.explainthatstuff.com/gears.html)|[introduction to mechanics]( https://www.cs.cmu.edu/~rapidproto/mechanisms/chpt7.html)|[mechanisms]( https://www.cs.cmu.edu/~rapidproto/mechanisms/chpt7.html)|[classification of gears](https://www.google.com.ng/amp/s/me-mechanicalengineering.com/classification-of-gears/amp/).
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<center>https://steemitimages.com/DQmeqXkd5iiKxkeTXDhAX3MW7V8bL59TF28pTtf57toNvDz/gear.gif</center>