Gears

 

Gears Documentation Blog Entry

1.    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

Indicates the size of the tooth of the gears. Gears can only mesh with each other if they have the same gear module. 

 

Pitch Circular Diameter(PCD)

Pitch circular diameter is the diameter of the gear measured from the center of one tooth of one end of a gear to the other. 

Relationship

The gear module is directly proportional to the PCD based on the formula for finding the gear module. 

 

 

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

Gear ratio is the number of teeth of the driven gear as compared to the driver gear. When the ratio is 1>, it is considered to have a higher output speed. When the gear ratio is 1<, it is considered to have a low output speed.  

Below is the relationship between gear ratio and torque for a pair of gears.

When the gear ratio increases, the torque decreases. When the gear ratio decreases, the torque increases. 

This can be seen in bicycles, when switching the front gear(driver gear) of a bicycle to be smaller than the back gear(driven gear), it decreases the amount of force needed to rotate the wheel. However, it has a decreased speed. While switching the front gear of a bicycle to be larger than the back gear, it increases the amount of force needed to rotate the wheel, but increases the speed.

 

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

 

 

 First change 

The first change would be to add nuts and bolts on the gears to fix them in place. As the gears were not fixed in place and were loosely laid on top of each other, the gears would be moving around a lot which made it hard for the fan to be used while holding it up due to gravity. This change will ensure that the gears will be able to work properly no matter what position it is held in.

Second change

The second change would be to add an additional link between the shaft of the crank handle. This will allow for easier use of the fan as previously, we had to make sure that the shaft is aligned and rotating the gear. This link will make it easier for the gear to turn when we press on the handle.

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.

 

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

 

 

5.    Below is my Learning Reflection on the gears activities 

 

The gear practical was very fun, I think it mostly had to do with the interactiveness of it, and being able to see how the mechanism worked up and close.    

One of the main issues we had was the assembling of gears for activity 1. The gears were either too tight, making it hard to crank, or were too loose, making it impossible to lift up the bottle. Our group had to tweak it bit by bit to make sure it was able to accomplish its task. This was quite frustrating as even through the end product it wasn't what we expected it to be. 

Another issue we faced while doing activity one was fixing in the gears after arrangement. Placing the smaller gears atop the larger gears were impossible to screw as the screw would be blocked by the gear located at the bottom. We had to change the arrangement several times before we managed to find one that we were able to fix in. 

While focusing on activity 1, we failed to place more time into activity 2 and ended up trying to rush through it. This didn't allow us to be able to verify and check with each other on our work.  

For activity two the exploded drawing for the assembly was quite vague in some parts and left us to tinker and play around with what should go where. It was a little frustrating at first but was quite accomplishing when we managed to solve it.

Despite all of the mishaps I still think overall it was pretty interesting. I felt like all the mishaps that happened we took it quite well and just rolled with it. It made our group think on the spot and made me realize to not worry about the little details or that things don't go perfectly all the time. Sometimes its not always about the solution as it can change as things go and is mostly about how we manage to adapt to solve the problem.