Gear
In this page, I will describe:
The definition of gear module, pitch circular diameter and the relationship between gear module, pitch circular diameter and number of teeth.
The relationship between gear ratio (speed ratio) and output speed, between gear ratio and torque for a pair of gears.
How I can design a better hand-squeezed fan, including the sketches
How my practical team arranged the gears provided in the practical to raise the water bottle, consisting of:
Calculation of the gear ratio (speed ratio)
The photo of the actual gear layout.
Calculation of the number of revolutions required to rotate the crank handle.
The video of the turning of the gears to lift the water bottle.
My Learning reflection on the gears activities.
These are the definition of gear module, pitch circular diameter and the relationship between gear module, pitch circular diameter and number of teeth:
Gear module(m) - refers to the size of the gear teeth.
Pitch Circular Diameter(PCD) - It is the imaginary circle that passes through the contact point between meshing gears. It represents the diameters of two friction rollers in contact and moves at the same linear velocity.
Number of teeth(z)
Relationship between gear module, pitch circular diameter and number of teeth
m=PCDz
Below is the relationship between gear ratio (speed ratio) and output speed for a pair of gears.
The higher the gear ratio, the lower the output speed. The formula to find gear ratio is Number of teeth in follower gearNumber of teeth in driver gear.
Below is the relationship between gear ratio and torque for a pair of gears.
The higher the gear ratio, the higher the torque for a pair of gears. The formula to find gear ratio is Number of teeth in follower gearNumber of teeth in driver gear.
When gear ratio is >1, the number of teeth in the follower gear is higher than the number of teeth in driver gear.
Below are the proposed design to make the hand-squeezed fan better:
During the practical, while we were building our hand-squeezed fan, we had to make the gear ratio to be less than one so that the fan would speed faster when the fan is squeezed. When we were done building the hand-squeezed fan, the problem was the handle kept getting stuck because the materials were 3D printed and the fan was also not producing enough wind as well. Here a video of the hand-squeezed fan we build.
In order to improve the hand squeezed fan, I suggest that the gears used can be of a even lower gear ratio by having a lowest number of teeth in the follower gear and a highest number of teeth in the driver gear so that it will become a speed multiplier and the fan would spin more and produce more wind.
Below are the description on how my practical team arranged the gears provided in the practical to raise the water bottle.
Calculation of the gear ratio (speed ratio).
Gear ratio(total) = (4030)(4020)(4012)(4040)(3012)(2030)(4030)
= 11.852
The photo of the actual gear layout.
Calculation of the number of revolutions required to rotate the crank handle.
200mmCirc. of output=20cm2 x π x 2.2
= 1.446863119
no.of revolutions = 1.446863119 x input gear circ
= 1.446863119 x (2 x π x 2)
= 18.18
The video of the turning of the gears to lift the water bottle.
Below is my Learning Reflection on the gears activities
Overall, I felt that I have gained new knowledge which would help me in my project in making a teamake. For the activity where we had to lift the bottle up, the screw that was supposed to lock the gear in place was quite short and there were only two allen keys, we had to work around that so that the gear can be put in place and we lost some gear ratio. Here are some pictures we took during the practical.
In conclusion, this practical was an eye opener to the world of gears and I had fun doing the practical
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