Blog 1: Gears! ⚙⚙

Hi guys and welcome back to my blog!!! I'm so excited to be back and can't wait to get started on my new journey in CPDD!! As you may recall, last semester my blog was on ICPD, but a new semester means new modules, so I will be documenting on CPDD instead! CPDD is relatively similar to ICPD, but this time instead of theorizing concepts, we will be implementing them in real time!

1.1: Gears, what exactly are they?🤔

At their heart, gears are simple yet brilliant mechanical devices designed to transmit motion and power from one place to another. They consist of toothed wheels that mesh together to achieve various mechanical tasks—speeding things up, slowing them down, or making them stronger!📦💡 They work by interlocking teeth (like puzzle pieces) that ensure smooth and controlled movement without slipping. When one gear (the driving gear) rotates, it pushes the teeth of the gear it’s connected to (the driven gear), causing it to rotate as well. Depending on the size and number of teeth of each gear, this interaction can change speed, torque and direction!

I'm sure that you come across or even use devices with gears almost everyday in your lives, from bicycles to watches to even printers! Gears are toothed wheels that transmit motion and power between shafts. Three fundamental concepts underpin gear design and function:

Gear Module (m):Think of it as the "size of the teeth." It’s calculated using:

m=d/z

Where d is the Pitch Circular Diameter and z is the Number of Teeth. A larger module means bigger teeth, which are great for heavy-duty work! 💪

Pitch Circular Diameter (d):Imagine an invisible circle running through the middle of the gear teeth—this is the pitch circle. Its diameter helps determine how gears mesh smoothly.

Number of Teeth (z):This one’s simple—it’s how many teeth a gear has! The more teeth, the smoother the motion.

Relationship:These three are inseparably linked by the formula:

d=m x z

Bigger gears with more teeth generally operate more smoothly, but design choices depend on the application. Gotta love math, right? 😄✨

1.2: Gear Ratios, The real force behind power and speed⚡

Now that we've established what gears are and how they work, let's take a look at gear ratios and how they affect the efficiency of gears! The Gear Ratio is the magic formula that controls the relationship between the speed and torque of connected gears. It’s calculated as:

Gear Ratio=Number of Teeth on Driving Gear/Number of Teeth on Driven Gear​

Speed Ratio: Fast or Slow? 🚗🐢

• A higher gear ratio means the driven gear spins slower than the driving gear, ideal for heavy lifting.

• A lower gear ratio lets the driven gear spin faster, perfect for speed!

For example, in bicycles:

• Smaller front gear + larger rear gear = climb hills slowly but powerfully. 🚴‍♀️💪

• Larger front gear + smaller rear gear = zoom down straight paths! 🚴‍♂️💨

Torque Ratio🔧:

Torque is the force that makes things rotate. A higher gear ratio increases torque but decreases speed. That’s why trucks can pull heavy loads—they’re built for torque! 🚚💥

1.3: Hand-squeezed fan

Now, let's put all the principles we've learned so far into action! A hand-squeezed fan works by converting the squeezing motion into rotational motion that spins the fan blades. The key challenges are:

1. Efficiency: How to get the most rotation with the least effort.

2. Speed vs. Torque: Finding the right balance between speed (how fast the fan blades spin) and torque (how much force is needed to spin them).

3. Portability: Keeping the fan light, compact, and user-friendly.

In order to make an improved design of the fan, there are 3 things I need to do. First is to use a high gear ratio, second is to add a one-way clutch and the third is to minimize friction.

• A higher gear ratio makes the fan blades spin faster relative to the motion of the handle.

• For example:

  • Driving gear (connected to the handle): 10 teeth

  • Driven gear (connected to the fan blades): 50 teeth

  • Gear Ratio = 50/10 = 5 (The fan blades spin 5 times for each squeeze).

A one-way clutch ensures the fan blades keep spinning after each squeeze, maintaining airflow without interruptions.

Use self-lubricating materials like nylon or Teflon for the gears to reduce energy loss and ensure smooth operation.

1.4 How my team managed to raise the water bottle🌊⚙

Unfortunately, I was not able to go for the practical as I was sick, so I did not get to participate and know how my team was able to lift the bottle with the gears, but I can provide a rough idea on how they did it!

Step 1: Understanding the Inputs

1. Weight of Water Bottle (W):A 1 L bottle weighs approximately 10 N (assuming gravity = 9.8 m/s²).Adjust calculations based on the actual bottle weight provided by the lecturer.

2. Winch Radius (R):Given: Winch is connected to a Gear 40T with Winch. Measure the winch radius, as 1 revolution moves the rope by 2πR2 \pi R2πR.

3. Handle Force (F) and Handle Radius (rh​):The handle radius is the distance from the axis to where the force is applied. This is crucial for torque calculations.

Step 2: Calculate the Torque Required at the Winch

Torque (T) at the winch is calculated as:

Twinch=W x R

Where:

• W = weight of the water bottle (N).

• R = radius of the winch (m).

Step 3: Design the Gear Ratio for Mechanical Advantage

The gear train must provide a mechanical advantage such that the torque applied at the handle is amplified to meet the required winch torque.

Relationship Between Torque and Gear Ratio

Gear Ratio (Speed Ratio)=Twinch/Thandle=Torque at Winch/Torque at Handle\text{Gear Ratio (Speed Ratio)} = \frac{T_{\text{winch}}}{T_{\text{handle}}} = \frac{\text{Torque at Winch}}{\text{Torque at Handle}}Gear Ratio (Speed Ratio)=Thandle​Twinch​​=Torque at HandleTorque at Winch​

The torque at the handle is given by:

Thandle=F⋅rhT_{\text{handle}} = F \cdot r_hThandle​=F⋅rh​

Where:

• F = force applied at the handle (measured using a luggage scale).

• rh​ = radial distance of the handle (m).

Using the provided gears, arrange them to achieve the desired gear ratio (GRGRGR):

GR=Driven TeethDriving TeethGR = \frac{\text{Driven Teeth}}{\text{Driving Teeth}}GR=Driving TeethDriven Teeth​

Step 4: Sketch and Arrange the Gears

Gear Options Provided:

1. Driving Gear (Handle Options): Gear 30T or 50T.

2. Intermediate Gears (Compound/Idler): Gears with multiple teeth combinations (e.g., 20T-40T).

3. Driven Gear (Winch): Gear 40T with winch.

Sketch the Layout:

1. Select the handle gear (e.g., Gear 50T) as the driving gear for higher initial torque.

2. Use compound gears (e.g., 20T-40T or 12T-40T) to achieve step-by-step amplification of torque.

3. Connect the final gear to the 40T winch gear.

Step 5: Calculate the Speed Ratio

For each gear connection:

Speed Ratio=Driven TeethDriving Teeth\text{Speed Ratio} = \frac{\text{Driven Teeth}}{\text{Driving Teeth}}Speed Ratio=Driving TeethDriven Teeth​

Multiply the speed ratios of all connections in the train to get the total gear ratio:

Total Gear Ratio=∏(Driven TeethDriving Teeth)\text{Total Gear Ratio} = \prod \left(\frac{\text{Driven Teeth}}{\text{Driving Teeth}}\right)Total Gear Ratio=∏(Driving TeethDriven Teeth​)

Adjust the gear arrangement iteratively until the gear ratio provides sufficient mechanical advantage.

Step 6: Calculate Revolutions of the Handle

To raise the bottle by 200 mm, determine how many revolutions are needed at the handle:

1. One winch revolution lifts the bottle by: Lift per Revolution=2πR\text{Lift per Revolution} = 2 \pi RLift per Revolution=2πR

2. Total revolutions of the winch (NwinchN_{\text{winch}}Nwinch​): Nwinch=Lift DistanceLift per Revolution=2002πRN_{\text{winch}} = \frac{\text{Lift Distance}}{\text{Lift per Revolution}} = \frac{200}{2 \pi R}Nwinch​=Lift per RevolutionLift Distance​=2πR200​

3. Total handle revolutions ): Nhandle=Nwinch⋅Total Gear RatioN_{\text{handle}} = N_{\text{winch}} \cdot \text{Total Gear Ratio}Nhandle​=Nwinch​⋅Total Gear Ratio

Step 7: Testing the System

1. Rotate the handle to check if the gear train lifts the bottle smoothly.

2. Observe and record:

   • If any gear misalignments or excessive friction occur.

   • Adjust gear spacing and ensure screws are properly tightened to improve smoothness.

Step 8: Observations and Solutions

If gear friction is observed:

• Adjust Gear Alignment: Ensure teeth mesh correctly.

• Reduce Tension: Avoid over-tightening screws.

• Minimize Weight on Idlers: Use lightweight idler gears if friction is excessive.

1.5: Reflection

The gears activity was an eye-opening experience that highlighted the brilliance of mechanical systems and their practical applications! ⚙️💡 It was fascinating to see how gears amplify torque and reduce effort, especially when lifting the water bottle with minimal force. While calculating gear ratios and designing the gear train required precision and problem-solving 🧮🔧, it was so rewarding to watch the theoretical concepts come to life in motion. Challenges like aligning the gears and minimizing friction taught me the importance of attention to detail and iterative improvement 🔄✨. Working with my team made the process even more enjoyable as we combined our skills to troubleshoot and refine the setup 🤝💪. Overall, this hands-on session not only solidified my understanding of mechanical principles but also gave me a new appreciation for the ingenuity behind everyday machines! 🚀🎉