The document discusses the design of a gearbox for lifting a minimum weight of 8kg within size constraints using a motor with specified torque. It analyzes torque requirements and determines a gear ratio of at least 30.1x is needed. Different gear types are considered and spur gears are selected for simplicity. An initial overlapping gear design is presented that is compact, repeats for scaling, and fits in a 63mm cube allowing future modifications.

1. ‘Creative Journey’
Group XYZ
Rhys Morrison, Bryan Sito, Kevin Huynh, Samuel Warren

2. Understanding the Problem
Performance ‘𝑝’ = (𝑚𝑔ℎ/𝑡𝑉𝐼)*(𝑚𝑔ℎ/𝑡D3)
 Weight (m)(kilograms): 8 -> ??? Kg
 Height (h)(metres): 0.5 -> 1m
 Time (t)(seconds): As few as possible
 Max. Axial Length (D)(metres): Minimize as much as possible
 g = 9.8m/s^2 V = 6V I (nominal) = 2.6A
 Motor Torque (nominal) = 80g.cm

3.  Find output torque required on 6mm shaft to lift minimum 8kg weight
T = F.R = mg*0.003m = 8*9.81*0.003 = 0.23544N.m = 2400.82g.cm
 Compare to input torque to find required conversion for gearbox
 (Specification sheet) 80g.cm = 0.00784532N.m input torque
 0.23544/0.00784532 = 30.010 conversion needed
 Design a gearbox using standard gears to achieve required ratio
 Create iterative solutions to achieve maximal performance balance of weight and lift speed
without overloading motor or building to excessive size

4. Derive gear sizes, pitch circle diameters (hence effective radii) and ratios from construction
sketches

5.  18mm/8mm = 2.25 Gear ratio
 2.25^? = 31.01
 ? = 4.52 gear-downs required to lift minimum weight at listed motor performance

6. Choosing Parts
 Worm gear – high reduction, inefficient, near-impossible to machine
 Bevel gear – multiple planes means possible space saving, difficult to machine
with laser cutter, more shafts required
 Planetary gear – high reduction, complex design, large complex mounting
system required including bearing – hard to make from acrylic
 Helical – runs more smoothly, difficult to machine
 Basic Spur gear – designs already supplied, simple to machine

7.  Large axial length
 Loss in power
 Not efficient

8. • Driving gear(back) convert torque
into speed, and the speed again
convert into torque
• Not efficient
• A third, larger type of gear
• Greater ratio
• Size constraints

9. • Driving gear(back) convert speed
into torque
• The smaller(front) gear which move
along with the big gear then drive
the output gear
• Not efficient

10.  Planetary gear system

11. “Final” Initial design
• Overlapping gear
structure, highly
compact
• Diagonal placement
to reduce axial length
• Simple, repeating
design. Easy to
modify
• Cubic shape gives
maximum volume
with minimum side
length
• 63*63mm, including
side tabs
• (Motor mounting not
finalized)

12. • Top-down view of gearbox showing
alignment of gears.
• Significant room to play around with
• Slight separation of each gear to avoid
friction. Include small washer or spacer