GEARS

What's up guys!!! Welcome back to my blog! For our second practical of CPDD, we are going to be learning more about gears and how they work.

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 refers to the size of the gear teeth. The unit for module is mm. The larger the module number, the larger the size of the teeth. Gears that mesh together have the same module

Pitch Circular Diameter is 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 refers to the numerical amount of teeth on the gear

The relationship between the gear module, pitch circular diameter, and the number of teeth is represented by the equation below:

Module (m) is Pitch Circular diameter (PCD) over the number of teeth (z)

2. Below is the relationship between gear ratio (speed ratio)and output speed for a pair of gears.

Gear ratio (Speed Ratio) is the ratio of the number of teeth of the follower gear over the number of teeth of the driver gear.

When Gear Ratio > 1, it becomes a torque multiplier as the follower gear will have increased torque and a decreased speed output. For example, the driver gear is small and has 20 teeth while the follower gear is big and has 40 teeth, this would lead to a gear ratio > 1 and result in decreased speed for the big follower gear with 40 teeth

However, when Gear Ratio < 1, it becomes a speed multiplier as the follower gear will have decreased torque but an increased speed output. For example, the driver gear is big and has 40 teeth while the follower gear is small and has 20 teeth, this would lead to a gear ratio < 1 and result in increased speed for the small follower gear with 20 teeth.

3. Below are the proposed design to make the hand-squeezed fan better:

Ideally, the concept of the fan is to make the turbine spin as fast as possible, with that knowledge in mind we would like to implement a speed multiplier-type gear train. To do so we need to have the gear ratio of the gear train be less than 1 because when the gear ratio is less than 1, the gears are a speed multiplier where torque decreases and speed increases. Thus we used the bigger gears at the gear input and smaller gears closer to the gear output.

Here is the outcome of our finalized gear train arrangement:

Here are the workings of the fan activity for the gear ratio:

Here is a video of the fan turbine revolutions:

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 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

Explanation: We knew that we had to raise the water bottle 20 cm into the air so we calculated the amount of distance the winch would reel up in 1 revolution. After that, we divided the distance that we needed to reel in with the distance reeled in with 1 revolution of the output gear. The value 1.010507 is how many revolutions of the gear output are needed to reel the water bottle 20cm into the air. We multiplied that value by the gear value to get the number of revolutions required to rotate the crank handle which is 27.

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

5. Below is my Learning Reflection on the gear activities

All in all, today was my favourite W3 experience throughout my close to 2 years in chemical engineering. The team was extremely efficient and we delegated the work perfectly. The team dynamic was very smooth and we completed the questions and the activity with ease.

Although some of the questions were quite tough, the satisfaction we get when accomplishing success after putting in our 100% was worth it.

Activities 1 and 2 were very beneficial to help us practice problem-solving and teamwork. Some of the questions needed us to think outside the box and practice analytical thinking while some of the theory questions had us practice metacognition and think about why would we do a certain step.

The only thing to improve on is to work harder to consistently produce these kinds of results. I hope we can continue to put in the hard work to keep up the good work as a team.