The document provides details about a gearbox project to lift an 8 kg weight between 0.5 and 1 meters using an acrylic gearbox powered by a provided motor. It specifies possible gear arrangements including spur, helical, bevel, rack and pinion, worm, and planetary gears. The pros and cons of each arrangement are discussed. It indicates that a spur gear arrangement was selected for the project due to its simplicity, ease of manufacture, efficiency, and ability to still function if some teeth are damaged. Performance projections are also presented.

1. MEE30003 - Gearbox Project
Will Huson - 7694210
Brent Farnsworth - 4922581
Jarrod Kline - 7694172

2. Design Brief
 Gearbox built to lift an 8 kg weight
 Must lift to a height between 0.5 and 1 metre
 Will be powered by a provided motor
 Will be secured to a specified mounting plate
 Can only be made from acrylic, glue and string

3. Motor Specifications
 Jaycar YM2712
 Max power:
Power Output = 6.44 W
Speed = 7845 RPM
Torque = 80 g.cm
Current = 2.6 A

4. Acrylic Properties
• Transparent, colourless
• Easily shapeable
• Scratch resistant
Property Value
Young’s Modulus 1.8-3.1 GPa
Bending Strength 120-148 Mpa
Fracture Strength 48-76 Mpa
Friction Coefficient 0.54
Density 1170-1200 kg/m3

5. Acrylic Uses
• Automotive/ transport
• Glass substitutes
• Furniture
• Lighting
• Architecture

6. Gear Arrangements
 Possibilities
 Advantages and Disadvantages

7. Spur
Pros
 Simple to use and manufacture
 Efficient due to the fact that the teeth
roll instead of slide (94%-98%)
 No friction
 Supplies a constant velocity ratio
 Can transmit a large amount of power
Cons
 More expensive than worm gears
 Limited tooth interaction between
mating gears, which reduces the torque
carrying capacity
 Produces noise at high speeds

8. Helical Pros
 Highly efficient gear (94% - 98%
efficiency)
 Has more teeth constantly interacting
producing high torque
 Smooth and quiet operation
 Highly durable
 Ideal for high load applications
Cons
 Not self locking
 Would require precision manufacturing
and assembly from the materials at hand
 Subjected to thrust load if double helical
or herringbone gears are used

9. Bevel
Pros
 Can interact with other gears on an
angle, which can make the gear box
more compact
 Can be quiet and smooth if spiral teeth
are used
 Efficiency of 93% - 97%
Cons
 Most be precisely mounted
 Limited gear ratio
 The shaft experiences large force
 Each gear can only operate with its
complimenting gear

10. Rack and Pinion
Pros
 Robust design
 Compact and cheap to manufacture
 Easiest way to convert rotational motion
to linear motion
Cons
 Very inefficient
 Only works with certain levels of friction
 Subjected to wear

11. Worm
Pros
 Inexpensive
 Quiet
 Smooth when running in only one
direction
 They take up less space
Cons
 Not the highest efficiency (50% - 90%)
 Experience sliding friction, creates heat
and increases tooth wear
 If motor reverses, teeth will wear

12. Planetary
Pros
 Creates high gear ratios out of compact
gearboxes
 Low backlash
 Higher efficiency than a worm gear (80%
- 95%)
Cons
 Can be damaged from shock loads
 Lower efficiency than a spur or helical
gear
 Gear ratios lower than 30:1 are not
possible
 If a tooth shears then the whole system
fails

13. Selection - Spur Gear
• Simple to use
• Easy to manufacture
• High efficiency
• The noise factor will not
be an issue as
performance is the main
concern
• If some teeth shear, the
gears will still work
• If assembled in the correct
way, can take up less
space

14. System Losses

15. Projected Performance
Radius of draw shaft
(m)
T req'd
(Nm)
4 Gear Raise time
(sec) Config. 3G ESF
0.005 0.3924 19.71938874B3 1.49

16. Projected Performance

17. Gear Arrangement

18. Next Steps
 Model
 CAD Formation
 CNC First Cut

19. Questions