Gears⚙️

1)These are the definition of gear module, pitch circular diameter and the relationship between gear module, pitch circular diameter and the number of teeth
Gear Module (m) refers to the size of the gear's teeth. The unit for the gear module is (mm). The larger the gear module, the larger is the size of the teeth. Gears that are mesh together have the same module.

Pitch Circular Diameter (PCD) refers to the imaginary circle that passes through the contact point between two meshing gears. It represents the diameters of two friction rollers in contact and moves at the same linear velocity. The unit for PCD is (mm).

Number of Teeth (z) refers to the number of teeth the gear has.

The relationship between gear module, pitch circular diameter and the number of teeth: m=PCD/z

2a. Below is the relationship between gear ratio (speed ratio) and output speed for a pair of gears
Gear ratio is the ratio of number of teeth of the follower gear to the number of teeth of the driver gear. When the gear ratio is lesser than 1, it becomes a speed multiplier and therefore increases the output speed of the follower gear. For example, the driver gear is the bigger one and thefollower gear is the smaller one and there is a 2 times difference in size this would mean that for one revolution of the driver gear, there would be two revolution for the follower gear.

2b. Below is the relationship between gear ratio and torque for a pair of gears
When the gear ratio is greater than 1, it becomes a torque multiplier, therefore the torque of the gear increases. When the gear ratio is lesser than 1, hence it will decrease the torque of the gear.

3. Below are the proposed design to make the hand-squeezed fan better:
The hand squeezed fan makes use of the speed multiplying gear arrangement in a compound gear train to allow the fan to spin faster. To get the compound gear ratio, calculate the gear ratio of each contact point and multiply it together. Hence, we arranged the two contact gear from a bigger gear (driver) to a smaller gear (follower).

Here's a photo of the interal and external body of the fan

Here's the video of the fan in slow-mo

4. Below are the description on how my practical team arranged the gears provided in the practical to raise the water bottle

a. Calculation of gear ratio (speed ratio)

b. Photo of the gear layout

c. Calculation of the number of revolutions required to rotate the crank handle.
Circumference of winch = 2πr = 2(π)(31.5) = 197.92
Revolutions of winch = 200/197.92 = 1.01
Revolutions of driver gear = 1.01 × 0.8 = 0.81 revolutions

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

5. Below is my Learning Reflection on the gear activities

This practical was fun and hard at the same time, we were having fun assembling the gears for both activity 1 and 2, but for activity 1 we had to crack our brains on how we should arrange the gears as out first arrangement did not work out. So, we tried multiple different arrangements until we found the one that was the best, we were really happy with the end result as the driver gear did not even need 1 full revolution to bring the bottle up by 0.2m. It was also very interesting learning about the uses of gears and how the arrangement (simple or compound) can affect the result.

The 2 activities required me to tap into my thinking skill to find out ‘How do we arrange the gears to get the max amount of gear ratio?’, ‘How do we use arrange the gears to use the least amount of force needed to lift the bottle?’ and other question. I also had to tap into my problem-solving skill as we had faced some challenges along the way, a major one being the arrangement of gears for the 1st activity like I mentioned last paragraph. I also had to talk to my teammates most of the time as it is the best way to brainstorm together, which enables our group to quickly find a solution for the problems we faced.

Overall, I really enjoyed this experiment as it has a happy balance of fun and work, I would 100% recommended anyone to do these activities with their friends as it is also a good way to bond together whilst using your brain.