Gears

Hey guys! Welcome to my first blog for CPDD! It's been a while since I've done one of these, so I'm excited to dive back in! Anyways, in this blog, I'm gonna be documenting my journey exploring Gears for the past few weeks. I'll be going through certain concepts, including the definitions of terms like gear module and pitch circular diameter, and how they relate to the number of teeth on a gear. I'll also explore the relationship between gear ratio, speed, and torque. Then, I'll go over my proposed design for a more effective hand-squeezed fan. Following that, I'll walk you guys through my recent practical, where my group used gears to lift a water bottle. I'll include our calculations, gear layout photos, and a video of the gears in action. Finally, I’ll wrap this blog up with my personal reflections on everything I learned from these activities.

Now, without further ado, let's get started!

I'll now introduce everyone to my new friends! They kinda have a gang name. They're called the Gears!

say hi to my new friends

Honestly, I never wanted to be friends with them, but I did it anyway cause I wanted to use them for grades, like how some of y'all are only friends with people for answers HEHEHEHEHE ok.

LET'S FIND OUT MORE ABOUT GEARS!

(the lore ends here btw i dont know how to conitnue it lol)

To start using Gears effectively, we first need to understand the following concepts:

1. Gear Module

2. Pitch Circular Diameter

3. Relationship between Gear Modules, Pitch Circular Diamter, Number of Teeth

   
   

Gear Module refers to the size of the gear teeth, measured in millimeters (mm). The larger the module, the larger the teeth. Only gears with the same module can mesh together effectively for a gear system to work.

three different gear modules

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.

Number of teeth is just the number of teeth on a gear, I don't know what else to say.

These three terminologies can simply be related through the following equation:

m = PCD/z

where m is the Gear Module, PCD is the Pitch Circular Diameter and z is the Number of Teeth.

This equation allows us to easily calculate one of the variables if two of them are given. We can also observe that the PCD is directly proportional to m when z is constant, and z is inversely proportional to m when the PCD is constant. Pretty simple, right?

Well, understanding these key yet simple concepts provides us with a good foundation to analyse more complex aspects of gears, such as the relationship the between gear ratio and output speed for a pair of gears, as well as the relationship between gear ratio and torque. Let us first go over the definitions of gear ratio, output speed and torque.

Gear Ratio can simply be understood as the ratio of the number of teeth on the driven gear to the number of teeth on the driver gear. However, excluding using the number of teeth to find out the Gear Ratio, it can also be expressed in the following equations:

(btw Speed Ratio and Gear Ratio mean the same thing)

Output Speed simply refers to the speed at which the driven gear rotates. I don't really know what else to say other than that its affected by Gear Ratio, which I'll go over in the next bit.

Torque is the turning force when a load is applied at a certain distance away from the centre of rotation. In the context of gears, torque is transmitted from the driver gear to the driven gear. Its magnitude depends on the applied force and its distance from the gear's centre. (yea this part's kinda complicated but the definition's the definition ://)

With the definitions out of the way, we can now examine the relationship between Gear Ratio and Output Speed, as well as the between Gear Ratio and Torque!

A smaller gear would make more rotations in a fixed amount of time than a bigger gear. Hence, if we want a high output speed, we will need a smaller output gear, or driven gear. Taking into account the definition of Gear Ratio I stated earlier, we would need a smaller Gear Ratio for a higher Output Speed. The opposite is then true if a lower Output Speed is desired. Simply put, Gear Ratio is inversely proportional to the Output Speed!

As for the relationship between Gear Ratio and Torque, we can figure it out comparing the relationship between Gear Ratio and Output Speed. In gears, the higher the speed, the lower the Torque. As mentioned earlier, to achieve a high Output Speed, we would need a lower Gear Ratio. Hence, to obtain a lower Torque, we would also need a lower Gear Ratio. This tells us that the Torque is directly proportional to the Gear Ratio :D

ALRIGHT! With all the boring technical stuff out of the way, we can now move on to talking about how gears can be applied in practical scenarios (fun!).

Gears can be used for many different purposes, and in my practical last week, I got to use them to assemble a hand-powered fan, as well as to lift a water bottle up a certain height. Let's start off by talking about the hand-powered fan.

I'll just be straight up the fan sucked, like really bad. Not fun :(

not my photo btw thanks muzakir

The fan didn't really work well as the gears didn't rotate smoothly with the movement of the hand-powered mechanism. This made it hard to press down repeatedly to make the fan spin continuously. This was an even bigger problem as for each press of the mechanism, the fan only rotated about 10 times. For context, the portable handheld fans some of us use make about 10,000 rotations per minute. So yeah, the fan was weak. It was trash. It was useless. Don't buy it :(

(the portable fan im talking about)

BUTTTTTT we can't just sit here and complain about what's bad about the fan. This is a module about Chemcial Product Design anyways. So, instead of whining about the fan, I'm gonna come up with a proposed design to make the fan AMAZING (with sketches ill try my best please bear with me)!

WE NEED TO INNOVATE

Let's analyse each problem one by one to make this easier. I'll start by addressing the simpler problem of lack of rotation.

To increase the number of times the fan blades rotate, we can decrease the size of the driven gear attached to them. This decreases the gear ratio, making the driven gear rotate a greater number of times each time the mechanism is pressed. This in turn increases the number of times the fan blades rotate, hence improving the function of the fan! YAY! Of course, we won't be able to get 10,000 rotations a minute, but it'll definitely improve on the measly 10 rotations for each crank we had initially.

There is however a trade-off to doing this: Increasing the gear ratio makes the fan harder to rotate - but the mechanism was easy to press down when I tried it during my practical, so making it a bit harder to rotate shouldn't be a problem. The concern is more on the smoothness of rotation, not how hard it is to rotate, which I'll elaborate on now :)

So, how can I address this issue of rough rotation. Well, all I could think of initially was lubricating the gears, but that's not really a change in design. See, my creativity's still an issue but issa WORK IN PROGRESS.

Anyways, I had to do some research online to find out a solution, and the solution I believe the most feasible is......

ADDING A RETURN SPRING

'How would that work?', you may be asking yourselves. Well, a return spring would allow for the mechanism to return to its initial position after it is pressed, without needing to pull it back or unstick it while it returns. This would smoothen out the operation, allowing for quicker and more consistent pressing of the mechanism. yippeee

I've talked a lot, but you may not be able to visualise what I just descrbied. YOU DONT SEE THE VISION. But that's fine, below are two sketches, one being the original design, and one being the improved design. Hopefully, they help you understand how my proposed idea works!

Here's a sketch of the intial design

And here's a sketch of my modified design!

Okay the sketches may not the be the nicest but I TRIED MY BEST OK. I said in my ICPD blog that I failed Art in Sec 2 so please bear with me :). Hopefully, you can at least understand them, and that's what's most important. And if you don't, I really need to step up my Art game HAHAHAHA

Alright! That's all for the hand-powered fan. Let's move on to the Water Bottle activity!

This activity required to us come up with the correct gear layout to lift a water bottle up by 200m using a handle and a winch with minimal force. If I'm being honest we didn't have a thought process when arranging the gears. We were aware that we needed the highest possible gear ratio to only require minimal force, but yeah, this is how we got the layout:

1. Randomly arrange everything

2. Calculate the Gear Ratio

3. Compare with other groups

Yeah, probably not the most efficient way to do it, but it worked in the end, and that's what matters. It took a while though. The highest possible gear ratio was 26.67, but we were getting values less than 10 initally LOL. Anyways, below is a sketch of the gear layout, and how calculations were done to perform the gear ratio.

our sketch

our calculation

As you can see, the calculation was done by finding the gear ratio of each pair gears from left to right and multiplying all of them together. We had be careful though, as this was a Compound Gear Train, and we had to make sure we used the correct number of teeth on each gear for the calculations

So yeah, after all that trial and error, this was our final gear layout.

our gear layout

COOL!

Using our calculated gear ratio, as well as the diameters of the winch and the handle, we also determined the number of rotations required to bring the water bottle up 200mm.

However, this left us in confusion after comparing it with our actual results. Just watch the video below first.

https://video.wixstatic.com/video/a44068_1135a5df2b7a45c4a672ef1b3eb68b88/480p/mp4/file.mp4

As you can see, we needed to rotate the handle 49 times to lift the water bottle up 200mm, which is very far from the value of 29 that we calculated.

bruh

We couldn't really think of a real good explanation for this. All we could think of is that we may have left the bottle hanging by more than 200mm of string, and more revolutions were hence required to bring the bottle all the way up. But yeah honestly I have no idea. Ms Tan if you have an idea please us :D

Well, that's pretty much it for the water bottle activity, and in fact, that concludes my entire journey with Gears! YIPPEE KI YAY! Let me wrap things up with a brief reflection.

Overall, my journey exploring gears has been a fun ride! I never expected to be working with gears in this course, but here I am, actually enjoying experimenting with them! It's cool to learn more about stuff we don't typically learn in class, like the gear module, speed ratio and blabla. Getting to play with the gears hands-on was fun too! It certainly wasn't easy, but it felt good when my group and I finally got the gear layout right. As for the modified hand-powered fan, I have no idea if what I proposed would work HAHAHAHA. I'll only find out if I actually get to make it. Who knows? Maybe I'll need to do so in the future.

Alright! That's all I have for my first blog. Hope it's been a fun read for you guys! SEE YA :DD