Gears

 Gears Documentation Blog Entry

1.These are the definition of gear module , pitch circular diamater
and the relationship between gear module , pitch circular diameter and number of teeth:

Module is the ratio of reference diameter of gear divided by teeth

m=PCD/z

m: Module

PCD: Pitch circular diameter

z: No of teeth

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

Gear ratio= driven/driver

Speed ratio= Output speed/Input speed

Lower gear ratio, Higher speed ratio

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

Lower gear ratio, Lower torque

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

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)

30/30=1

30/30=1

30/20=1.5

40/30=1.33

40/20=2

20/40=0.5

40/40=1

Gear ratio= 1.5x 1.33x 2x 0.5 =1.995

b)The photo of the actual gear layout

c)Calculation of the number of revolutions required to rotate the crank handle.

2 turns of gear with handle is one turn of gear with winch

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

5. Below is my learning reflection on gears activities

In this practical, it was really fun and engaging!!! For our first activity, we met some problems in assembling the gears onto the board. As the screw is relatively small and very hard to screw it in. After we assembled our first design, the rotation did not go smoothly as the gears were not aligned nicely. This is because we did not calculate the gear ratio before aligning. Thus, we had come out second design, and we try to arrange and assemble it in a zig-zag shape. This is to allow the gears to be attached closely to make the rotation smooth. Moreover, to make the gears rotate more stable, we can put gears under so they can rotate more nicely. For the second activity, it was going well as we can assemble the fan and it works as expected. What we can learn from these two activities, we should always be prepared before we do hands-on. This will prevent us from putting in the extra effort. We should always look through the instructions before we do as we did not read through the instruction so we had planned the wrong design at first. Ergo, preparation before work is essential.