In this blog, I will be documenting my experience with the gears.
Learning the theory of how a gear works was very interesting and engaging because we are not learning or memorising from the textbook. We learned through discussions and hands-on activity to truly understand how the gears functions.
On 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:
4.1 Calculation of the gear ratio (speed ratio)
4.2 The photo of the actual gear layout.
4.3 Calculation of the number of revolutions required to rotate the crank handle.
4.4 The video of the turning of the gears to lift the water bottle.
5. My Learning reflection on the laser cutter activities.
1. These are the definition of gear module, pitch circular diameter and the relationship between gear module, pitch circular diameter and number of teeth:
Definition
Gear module (m)
Gear module refers to the size if the gear teeth.
Pitch circular diameter (PCD)
Pitch circular diameter is the imaginary circle that passes through the contact point between two mashing gears. It represents the diameters of two friction rollers in contact and moves at the same linear velocity.
where z represents the number of teeth.
The larger the module number, the larger the size of the teeth. Gears that mesh together are having the same module.
2. Below is the relationship between gear ratio (speed ratio) and output speed for a pair of gears.
Gear ratio (speed ratio) isthe ratio of the speed between input and output gears.
When the speed ratio increases, the output speed for a pair of gears also increases.
Below is the relationship between gear ratio and torque for a pair of gears.
Torque is the turning force of a lever. Torque can be increased in a gear by changing the size or output speed of the output gears. E.g., If I have a driver of 40t and a driven of 80T, this will have a lower output torque than say a driver of 40T and driven of 100T.
When the gear ratio increases, the torque of the gear increases.
3. Below are the proposed design to make the hand-squeezed fan better:
The hand-squeezed fan uses speed multiplying gear arrangement in a compound gear train to allow the fan to spin. A compound gear system with pairs of gears mounted on the same shaft can produce large speed changes hence, providing multiple outputs with different speeds and directions.
From the video, we can tell that the wheels make a lot of turns with one press of the lever.
4. Below are the description on how my practical team arranged the gears provided in the practical to raise the water bottle.
4.1 Calculation of the gear ratio (speed ratio).
4.2 The photo of the actual gear layout.
4.3 Calculation of the number of revolutions required to rotate the crank handle.
4.4 The video of the turning of the gears to lift the water bottle.
5. Below is my Learning Reflection on the gears activities I had a great time participating in the gear activity because I got the chance to bond with my team members through the discussion to brainstorm how to lift the water using gear by arranging the position of the gears to get a high gear ratio with minimum force. Also, tried to put the gears together for the hand-squeezed fan activity.
During activity 1, we misunderstood the objectives and had to rework them. Our first gear ratio was 0.2, but it was incorrect because we needed to achieve a high gear ratio so that we can use the minimum amount of force to lift the water. We rearranged it and from our third arrangement, we finally got a gear ratio that we think is acceptable which was 8.89. The trick is to pair the gears with similar no. of teeth together and pair gears with a massive difference in terms of the no. of teeth so we can achieve a high gear ratio. (letting the lesser teeth gear be the denominator).
For me, calculating the number of revolutions required to rotate the crank handle was the biggest challenge because I did not comprehend the information as all pieces of information were scattered... making me unable to piece them together. Hence, the answer we submitted during the practical was incorrect because the answer doesn't make sense to me.
Consequently, after the practical, I searched online for information on how to calculate gear revolutions and put the correct answer into this blog. Here's the video that I watched to learn how to calculate no. of revolutions.
Therefore, the key takeaway for this practical or in fact for all ICPD and CPDD practicals is that it taught us how to think outside the box and comprehend information quickly to find a solution to solve the problem as fast as possible. In short, trying to develop the ability to grasp new information quickly and be flexible is a crucial skill that all chemical engineers should have.
In the workforce, I assume we will be given multiple tasks or problems every day and the method we learn in SP may not be directly transferable because every company have different raw materials, technologies, unit operations, and size of operations. Thus, it is impossible to "copy" and "paste" whatever we learn in SP.
Therefore, ICPD and CPDD practical kind of simulate the workforce environment whereby we are given a task to solve a problem, however, we only have minimal knowledge on this topic. The lecturers are like our mentors guiding us along the way on how we should approach the problem to solve the issue instead of spoon-feeding us all the pieces of information.
This practical demonstrated the importance of resourcefulness, self-directed learning, and interpersonal communication when it comes to solving a problem. All these are essential skills for my internship.
