Process of acquiring ideas for a gear box project in our Machine design class.

1. Creative Journal
Group 394
Declan Howard, 7662645
Nathanael Oh, 7662882
Arsalan Shaikh, 726030x
SyedTaufiq, 100008499

2. Task summary
• Design and produce a gearbox out of an A4, 6 mm thick acrylic sheet, with
the ability to lift an 8kg weight a height of 0.5m as quickly and effectively as
possible

3. Torque & Ratio
• The amount of torque required to lift a 8 -10 Kg weight was calculated to be
approximately 0.3 Nm and at max efficiency, the motor outputs 0.006 Nm
torque.
• Based off these calculations, the reduction ratio for the gearbox should be
50:1.
• We have decided to use a reduction of 60:1 to reduce the stress on the
gearbox and also to allow for small variances in the weight of the object
and/or the output of the motor.

4. Calculations
𝑲𝒏𝒐𝒘𝒏 𝒗𝒂𝒍𝒖𝒆𝒔:
𝑀𝑎𝑠𝑠 𝑜𝑏𝑗𝑒𝑐𝑡 𝑡𝑜 𝑏𝑒 𝑙𝑖𝑓𝑡𝑒𝑑 : 10 𝑘𝑔 𝐺𝑟𝑎𝑣𝑖𝑡𝑦: 9.8 𝑚 𝑠2
𝑑𝑖𝑎𝑚𝑒𝑡𝑒𝑟 𝑜𝑓 𝑡ℎ𝑒 𝑠ℎ𝑎𝑓𝑡: 0.006 𝑚
𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 𝑡𝑜𝑟𝑞𝑢𝑒 = 𝑚 × 𝑔 × 𝑟
∴ 𝜏 = 10 × 9.8 × 0.006 = 0.294 ≈ 0.3 𝑁𝑚
𝑀𝑜𝑡𝑜𝑟 𝑜𝑢𝑡𝑝𝑢𝑡 𝑡𝑜𝑟𝑞𝑢𝑒 = 80 𝑔 𝑐𝑚 = 0.00588 𝑁𝑚
∴ 𝑜𝑝𝑡𝑖𝑚𝑎𝑙 𝑟𝑎𝑡𝑖𝑜 =
𝜏𝑖
𝜏 𝑜
=
0.00588
0.294
= 0.02 = 1: 50

5. Purposed Concept
Planetary Gearbox
Pros Cons
Compact design Need to be lubricated frequently
High efficiency in power transmission High bearing loads
Good load distribution Inaccessibility, hard to dismantle for
service
Large reduction in small volume Complex design
Pure torsional reactions

6. Grinder Gears
Pros Cons
Excellent speed reduction Complex design
Compact design Possibility of skipping at high speeds
Can bare heavy loads Untested in any industry
Large amount of friction within the gears

7. Fixed Axis Spur Gearbox
Pros Cons
High power transmission efficiency Limited centre distance
Compact velocity ratio Produce lots of noise
Highly reliable Cannot be used for long distance power
transmission
Can be use to transmit large amount of
power
Gear teeth experience large amount of
stress

8. Final Design
For our final design we have decided to choose the fixed axis system of spur
gears for our gear box.We believe this to be simple and yet very effective
method of completing the task.The Planetary Gear system and the Grinder
gear concept support load more efficiently but we feel that the complexity of
their designs is not necessary to satisfactorily complete to task.The simplicity
of the fixed axis spur gears is very agreeable as we only have two attempts to
print a working gear box.