Gears

Hello everybody and welcome back to my blog!! 

In this page, I will describe:

1.     The definition of gear module, pitch circular diameter and the relationship between gear module, pitch circular diameter and number of teeth.

2.     The relationship between gear ratio (speed ratio) and output speed, between gear ratio and torque for a pair of gears.

3.     How I can design a better hand-squeezed fan, including the sketches

4.     How my practical team arranged the gears provided in the practical to raise the water bottle, consisting of:

a.     Calculation of the gear ratio (speed ratio)

b.     The photo of the actual gear layout.

c.     Calculation of the number of revolutions required to rotate the crank handle.

d.     The video of the turning of the gears to lift the water bottle.

5.     My Learning reflection on the gears activities.

1. These are the definition of gear module, pitch circular diameter, and the relationship between the gear module, pitch circular diameter and number of teeth (z):

Gear Module (m)

-It refers to the size of the gear teeth. 

-The unit for gear module is mm.

-The larger the gear module is, the larger the size of the teeth.

- Gears that can mesh together have the same gear module. 

Pitch Circular Diameter (PCD)

-It is an imaginary circle that passes through the contact point between 2 meshing gears.

-It represents the diameters of 2 friction rollers in contact and moves at the same linear velocity

The relationship between gear module (m), pitch circular diameter (PCD), and the number of teeth (z) can be expressed as shown below: 

2. The relationship between gear ratio (speed ratio) and output speed, between gear ratio and torque for a pair of gears:

The relationship between Gear Ratio (Speed ratio) and output speed is: 

The relationship between gear ratio and torque is: 

3.  How I can design a better hand-squeezed fan, including the sketches

The original design of the hand-squeezed fan is shown below: 

When I was operating it, I noticed that the hand crank would often get stuck and did not rotate smoothly. 

This made me think about what could be modified while trying to crack it by squeezing it. Then I thought of adding a spring to the lever mechanism as it would help the crack "push out" so that the lever could be squeezed again to continue the momentum. This lead to the fan being more smooth when in use. 

The sketch for this idea is below: 

4. How my practical team arranged the gears provided in the practical to raise the water bottle, consisting of:

a. Calculation of the gear ratio (speed ratio)

The team laid out all the gears in an order that we think would work and calculated the gear ratio based on that arrangement which lead to these calculations: 

b.     The photo of the actual gear layout.

c.     Calculation of the number of revolutions required to rotate the crank handle.

d.     The video of the turning of the gears to lift the water bottle.

5. My Learning reflection on the gears activities.

After going through this practical, I got a better understanding of gears. This is because when I thought of gears, I had an impression that it was going to be boring and dry since it was just 2 objects that come together to turn. But after going through the videos that we had to watch before the practical, I learned many new things like torque multiplier and speed multiplier.

These were things that I have never thought of when someone mentions gears. The first thing that comes to mind is 2 objects that would turn when in contact with one another. I would have never knew that when choosing gears in a system, we would have to consider if we want the system to produce more torque or more speed. I would also have never know that for gears to mesh, the gear module would have to be the same and not the size of the gears. 

During this practical, I got to see firsthand how gear ratio actually worked and was impressed that when we cranked the first gear, it had enough torque to lift the water bottle that was filled with about 600ml of water in it. This taught me that gears are actually really useful when applied correctly.

For the second activity of the practical, when making the fan, I was a little skeptical as I did not think that the fan would be good as it was made up of very simple components and little components (mainly 2 simple gears, 2 compound gears and a hand crank). However, I was proven wrong as when I squeezed the crank once, the blade of the fan turned 10 times!! I was shocked by this as I really did not expect that to be possible. 

Overall, it was a fun practical as I got to understand gears alot better and now know that if I can apply it correctly, it would be a really "powerful" tool. I also enjoyed how the practical was really dependent on us as to how well we understood gears as there was no instructions or helping guidelines apart from the hints that Dr Noel gave, which was "the more teeth the gear have, the larger the diameter". This made us use alot of our brain power to carry out the practical. 

That's it for this blog! see you in the next one✌✌